Blooming Science-9-2077 final final for press

2. Animals of cold region have thick fur or long wool to keep their body warm. They bear
a thick layer of fat underling their skin to stop heat loss. They also have short and strong
feet. Polar bear has white hair which helps them blend with their icy surrounding and can
easily get their special food seals.

3. Animals of warm places have thin skin without long fur. Such skin helps them in easy
perspiration to balance their body temperature and stay cool.

Bear Camel Elephant

Cow Horse Zebra

Adaptational Features of Aerial Animals (Volant Adaptation)

The animals which spend most of their time on air are called aerial animals. Their adptative
features are as follows:

1. Birds have streamlined body to reduce air resistance.

2. Hollow and air filled (pneumatic) bones, wings and teethless beak make their body light
for flight. Air-sacs reduce body’s weight.

3. The beak and hindlimbs are modified as per their food capturing habits and the manner of
locomotion.

4. Birds those can swim have webbed toes and oil glands in their skin.

Rachophorus (Flying frog) Pigeon Draco (Flying lizard) Flying eagle

Blooming Science Book 9 251

Adaptational Features of Arboreal Animals

The animals which spend most of their time climbing on surfaces like wall trees are called
arboreal animals. Their adaptative characteristics are as follows:

1. They have tremendous climbing capacity.

2. The fore limbs of monkeys are modified to hold the branches of trees. (bipedal fore limbs).

3. The long prehensile tail also support climbing and jumping from one branch to other.

Squirrel Lemur

4. Wall lizard has lamella on the digit. This structural adaptation helps the wall lizard in
moving down on roofs or in ceiling walls. The adhesive pads on its limbs avoid falling
down.

Desert Animals

Desert animals are adapted for arid (dry) land and hot habitat e.g., camel, lizard, rodents, etc. The

adaptational characteristics of desert animals are as follows: ?DO

1. The nostrils in the case of many You
Know
desert animals are protected by A camel can drink 40 gallons of

complicated valves. water at once ie about 200 liters at

2. Desert animals are provided with a time. Arabian camels have one
very keen sense of sight, smell are hump while asian have two humps.

hearing.

3. They conserve water in water pouches (eg. camel).

4. They have thick skin to avoid loss of water.

5. Desert lizards have hygroscopic skin that absorbs water from
atmosphere just like a blotting paper.

6. Most of them have dull colour which blends them with the surrounding
environment.

7. The limbs of camel are provided with pad on the flat hoofs which help Camel
them to run on hot sand.

8. The body of camel is provided with hump on the back which stores fat.

252 Blooming Science Book 9

Cursorial Animals: Cursorial animals are those animals, which live in open places and are
adapted to run on hard ground. eg. lion, deer, dog, horse, etc. The adaptational characters of
cursorial animals are as follows:

(a) Leopard (b) Horse

i. The body is streamlined which helps them for swift movement.

ii. The limbs are long and strong, with reduction of digit for fast running. In some cases hoof
divides into two parts eg cow, sheep, etc. while in others it is a single eg, horse, ass, etc.

iii. Locomotion is digitigrade.

Fossorial animals: Fossorial animals are those animals which are adapted for burrowing
mode of life eg., rabbit, rat, mole, etc. The adaptational characters of fossorial animals are
as follows:

Rat Talpa (mole)

1. The head is small and tapers anteriorly to form a stout for digging.

2. The forelimbs are short with powerful claws.

3. The eyes and the ears are small or tend to reduce.

Some Justification
1. Root system is poorly developed in hydrophytes. The main function of root is to absorb

water. Due to easy availability of water, they have no roots or reduced roots without root
hairs and root caps.
2. Submerged and rooted hydrophytes have spongy and flexible stem and thin, long, ribbon
like leaves.
These features provide less resistance to water current and help them stand erect without
breaking.
3. The leaves and stem of aquatic plants are covered by waxy coating.
Wax acts as water proofing and stops the unnecessary passage of water through body
surface and avoids shrinkage and decaying of plant body.
4. Xerophytes have leaves modified into thorns with sunken stomata.
Such features help to reduce transpiration rate and loss of excess water in water-scarced
place. So, they support long life of xerophytes in desert.

Blooming Science Book 9 253

Let’s Learn

1. Body of lotus is covered with waxy substance, because lotus is an aquatic plant. Its
maximum part is always remain in contact with water. The waxy substance over the
surface of lotus protects it from decaying.

2. The camel is called ‘the ship of the desert’ as it is the most important beast of transport in
desert. The foot is modified in the form of flat hoof which helps them in swift movement.
The hoof has flat pad which does not sink in sand.

3. Aquatic plants have large air sacs in them, because the air sacs make the plants lighter to
float. Thus usually floating plant have such air-sacs.

4. Frogs have triangular head and webbed legs. It is because the triangular head reduces the
friction with water when the frog swims in water. The webbed legs also help in swimming
by pushing the water back.

5. An aloe plant has thick and fleshy stem, because it is a desert plant. Its thick and fleshy
stem helps to store water for the adaptation in desert.

6. Moles have strong stout and sharp claws, it is because, a mole is fossorial animal, which
digs hole to live in. It pushes the dug soil out of hole by using its strong stout and use the
sharp claws up to dig the hole.

7. Lizards have pads below their toes, it is because they are arboreal animals i.e., they can climb
up easily. Due to the presence of sticky pads below their toes help them to run at ceilings.

8. Birds have different type of beaks, because the beaks help them to take their different
types of food. The different types of beaks are adapted for different mode of nutrition.
Some of them help to pick up small grains of food, some to catch their prey and some of
them are adapted to eat flesh.

9. Ducks have flat beak and webbed legs, because they are aquatic birds. Their flat beak help
them to catch their prey in water and the webbed legs help them to swim in water.

10. Camels have flat hoofs with pads, it is because they are desert animals. There legs are
adapted for the hot sandy lands. The flat hoofs reduce the pressure on the sandy land and
the pads protect their legs from more temperature.

11. Person living at higher altitudes seem red, it is because at higher altitudes their lower
temperature, then to keep our body warm, it produces more RBC which causes red colour
in the face of a person.

Main Points to Remember

1. The features of the organism which is a definite significance in allowing organism to exist
under conditions by changing its parts (morphological or physiological) is called adaptation.

2. Aquatic plants have stem, leaf and roots modified to survive in water.
3. Aquatic animals have fins for swimming, gills for respiration and the body is streamlined.

This structure help them to survive in water.
4. The plants of desert have adapted to survive in severe drought and they possess thorns,

they are small bushes and possess thick barks.
5. The animals have modified legs according to the model of preying and feeding habits. The

254 Blooming Science Book 9

body of birds is covered with feathers and they possess air sacs that help them fly.

6. The structure of the teeth, claws on the limbs are modified to adapt according to the conditions.

7. Mesophytes have well developed root and shoot systems.

8. Xerophytes have well developed root system with thick and fleshy leaves or modification
of leaves into spines.

9. Cursorial animals have long and strong legs for running.

10. Fossorial animals have strong stout to push soil and sharp claws for digging holes.

11. Arboreal animals have plantigrade movement and stout body.

12. Birds have sharp eyes, pneumatic and light bones, wings and special shape of their beaks
according to their food.

13. Xeric animals like camels, have wide hoofs with pads, thick skin, hump and valved nostrils
for desert adaptation.

PRO J ECTWORK

1. Collect pictures of following organisms and paste them on a chart paper in attractive
pattern with two adaptational characters of each.

(i) Any two aquatic plants (ii) Any two aquatic animals

(iii) Any two mesophytes (iv) Any two xerophytes

(v) Any two cursorial animals (vi) Any two fossorial animals

(vii) Any two arborial animals (viii) Any two aerial animals

(ix) Any two himali animals (x) Any two xeric animals

Exercise

1. Answer the following questions.
a. What is adaptation?
b. What are the modifications made in aquatic plants to adapt in water?
c. What are the modifications made in xerophytes?
d. What are the features of aquatic animals that help them survive in water?
e. What are the significant changes in birds to adapt as aerial animal?
f. Discuss the modifications in terrestrial animals to survive in cold regions.
g. Discuss the modifications in terrestrial plants to survive in high altitudes.
h. Differentiate between
(i) Aquatic plants and terrestrial plants
(ii) Aquatic animals and terrestrial animals
i. Why is the body of aquatic plants and animals covered with wax or lily scales?

Blooming Science Book 9 255

j. Observe the given organisms and write down any two adaptive features of each.

k. Explain the modification seen in body parts of arboreal animals.

2. Give reason.

(a) The stem and leaves of hydrophytes are covered with a waxy substance.

(b) Polar bears are white in colour.

(c) Breast muscle is stronger and more developed in birds.

(d) Aquatic animals posses air sacs or swim bladders in their bodies.

(e) The body of yak found in Himalayan region is covered with thick fur while buffalo
found in jungle of Terai has only thin hair

(f) Desert animals remain hidden in burrows in day time and active at night.

(g) Wall lizards are not seen during winter.

(h) Person living at high altitude seem red.

(i) Bones of birds are light and hard.

(j) Water hyacinth has air storage tissue.

(k) Crane has sharp and pointed beak.

(l) Bones of birds are light and hollow.

(m) Aloe has thick and fleshy leaves.

3. Write in short:

(a) Fossorial animals (b) Cursorial animals (c) Mesophytes


256 Blooming Science Book 9

B. Micro Organisms

Virus

The word ‘virus’ is derived from the Latin word ‘Veron’ or ‘Venom’ that means poison. The study
of virus is called virology. Virus was discovered by Ivan Iwanoski in 1892 AD as an extremely
small micro-organism. He described the infectious nature of Tobacco Mosaic Virus (TMV).
Viruses are the ultramicroscopic nucleoprotein entities that reproduce only inside the living cells.
They are metabolically inactive outside the host cell because they do not have enzyme systems
and protein synthesis machinery. Thus, they are obligatory intracellular parasites. In other words,
viruses are known as obligatory parasites as they are fully dependent on the living organisms for
multiplication. They are inert outside the host cell. It is host specific, i.e. particular type of virus
can survive inside a particular cell only. In 1981, Mathews defined virus as a set of one or more
nucleic acid template molecules, normally enclosed in a protective coat of protein which is able
to organize its own replication within a suitable host cell.

Inside the host cell the virus particle is integrated into molecular constituents for replication
phase of virus is called eclipse phase.

General Characters

1. They do not have cellular structures. They are ultra microscopic and size is measured in
nanometre(10-9m).

2. They can live only parasitically inside other cells. So, they are called obligate parasites.
3. They have simple structure, consisting of a small piece of nucleic acid, either DNA or

RNA, surrounded by a piece of protein known as capsid.
4. They are on the boundary between what we regard as living and non-living.
5. Each type of virus can recognize and infect only certain type of cell, i.e. they are highly

host specific.
6. Viruses cannot be cultured in synthetic medium.
7. During reproduction, the virus particle disintegrates into molecular constituents in the host

cell. This phase is called eclipse phase.
Viruses show both the living and non-living natures. So they are also called biological

puzzle or border line between living and non-living things.

Non-living Characters of Virus

1. They lack cell organelles and cytoplasm because they multiply only inside host cell.
2. They do not possess the machinery necessary for generating energy and synthesizing

protein. They depend on their hosts for their survival and multiplication.
3. They are incapable of performing life functions outside of their host cells.
4. Viruses cannot reproduce by fission or conjugation.
5. Viruses can be crystallized e.g. tobacco mosaic virus. The virus crystals are chemically

inert and can be preserved in dry state without losing their activity.

Blooming Science Book 9 257

Living Characters of Virus

1. They are obligatory parasites because they multiply only inside host cell.

2. They have their own genetic material in the form of RNA or DNA.

3. They are capable of replication inside the host cell.

4. Viruses can mutate and change the characteristics of virulence like cells.

5. They occur in definite races, strains, with specific characters.

6. They respond to heat, chemicals and radiations.

Viruses exist in extracellular and intercellular forms.Outside the host cell, they are macromolecular
aggregates, incapable of any independent metabolism and can seem as non-living being. But
within the host cell, they are capable of performing biological and functions necessary for their
survival. In this regard viruses can be said living beings.

Viruses are generally regarded to be organisms because they are capable of attaching to proper
host cell to begin infection and self-replication. It is more useful to refer viruses as functionally
active or inactive, instead of regarding as living or non- living. A virus particle which is mature
and remain outside the body of host is called virion.

Types of Virus

Viruses are categorized according into two ways.
1. On the basis of type of host and
2. On the basis of type of nucleic acid ( ie, RNA and DNA virus)
1. Types of virus on the basis of type of Host

(a) Animal Viruses: These viruses are able to infect the animal cell including human. After
entering into the animal cell, they disturb the cellular metabolism. As a result various
diseases are caused to animals.They have wide range of morphological shapes and size.
They contain DNA as genetic material. Some animal viruses are rabies virus, mumps
virus, retro virus, rhino virus, polio virus, etc.

(b) Plant Virus: These viruses are obligate parasites of plants and cause several plant
diseases. These viruses have RNA as genetic material, but cauliflower mosaic virus has DNA.
More than 300 viral diseases are known.The plant viruses cause the loss of many cultivated
crops. Some important plant virus include Tobacco mosaic virus (TMV), yellow veinmosaic
of lady’s finger, Grassy shoot of sugarcane, Banana Bunchy top virus, Potato leaf roll virus,
cotton leaf curl virus, etc.

c) Bacteriophage: These viruses infect bacterial cells and Head DNA
damage them. They have been isolated from animal excreta, Tail
sewage, water and soil. According to shape they are either Neck
icosahedral tailless filamentous or helical or head and tail Collar Basal
plate
shaped. Most of them consist DNA as genetic material. It has two Sheath

parts-head and tail. The head is icosahedral (95 x 65 nm). Tail

is cylindrical (115 x 17 nm) in outline. At the place of union of

head, the tail bears a flat plate called collar. Tail also contains a Tail
hexagonal basal plate or end plate. Each of the six corners of basal fibres
plate bears a long tail fibre. Head contains DNA at the centre.

258 Blooming Science Book 9 Fig: Bacteriophage

Importance of virus:
a) Some virus like pox virus is used to extract vitamins like biotin and riboflavin.
b) Some virus like chicken pox is controlled by cow-pox virus ie cow pox is used as
vaccine.
c) Virus are used to control bacteria.
Control of virus:
i) Removing the effected parts from plants.
ii) Using vaccines against virus.
iii) Maintaining healthy environment and personal hygiene.

Some of the diseases caused by virus, effective organ, mode of transmission and preventive
measures are given below:

S.N. Name of Name of Effective organs Mode of Preventive Symptoms
disease virus transmission measures

1. Common Rhino Upper portion of Mucus and Covering of Inner layer of nose
cold virus the respiratory sneezing mouth while becomes red, Headaches,
system droplets sneezing and over blow of nose, fever
coughing

Respiratory

2. Mumps Paramyxo system, salivary Saliva and Covering of Intermittent fever, Ache
virus glands, all parts sneezing (water mouth while at the parotid glands,
of body due to droplets) sneezing and swelling of parotid
circulation of coughing. glands, swelling of testes
blood and testes of in males, Paralysis

male.

3. Measles Paramyxo Mouth, respiratory Mucus and Vaccination High fever, wet eyes,
virus tract, skin and saliva against the throat sore, eyes are
intestine disease. more sensitive to light.

4. Polio Polio Pharynx, intestine Saliva, mucus Polio drops High fever, stiffed neck
Blood and spinal and faeces (oral)
cord

5. Rabies Rabies Spinal cord Saliva of Anti rabies Hydrophobia, severe
infected wild vaccination pain at bite, contraction
and domestic of muscles, problem in
animals swallowing.

6. AIDS Retro Skin, Blood and Sexual Use of sterilized Cough, high breathing
(HIV) Brain contact, blood needle, Avoid rate, problem in
(containing unsafe sexual swallowing, lose motion
HIV) contact, Receive of faces loss in weight,
transfusion blood without Tiredness etc.
HIV

Bacteria

Bacteria are a large domain of prokaryotic micro-organisms. Typically, they are a few micrometer
in length and wide range of shapes, ranging from spheres to rods and spirals. Bacteria are present
on most habitats on earth, growing in soil, acidic hot springs, radioactive waste, water and deep
in earth’s crust as well as in organic matter and live bodies of plants and animals, providing
outstanding examples of mutualism in the digestive tracts of humans, termites and cockroaches.
The vast majority of bacteria are rendered harmless by the protective effects of the immune
system and a few are beneficial. However, a few species of bacteria are pathogenic and causes
infectious diseases including cholera, syphilis, anthrax, leprosy and bubonic plague. The most

Blooming Science Book 9 259

common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about
2 million people a year.

Bacteria are the smallest free living organisms. The size of smallest bacterial cell is 0.15 to 0.3
mm and the size of largest bacterial cell is about 500 mm in length. Majority of bacteria range
from 0.5 - 1 mm in width and 2-5 mm in length.

Streptococci
( Streptococcus

pyogenes)

Diplococci Chain of bacili Vibrio
( Streptococcus ( Bacillus anthracis) (vibrio cholerae)
pneumoniae)
Tetrad

Flagelate rods Spirilla
( Salmonela typhi) (Helicobacter pylori)

Staphylococci Sarcina Spore-former Spirochaetes
( Staphylococcus ( Sarcina (Clostridium (Treponema pallidum)
ventriculi) botulinum)
aureus )

Fig. Different shapes in Bacteria

Fig. Different shapes in Bacteria

Capsule
Cell wall
Plasma membrance

Cytoplasm
Ribosomes
Plasmid
Pill

Bacterial Flagellum
Nucleoid (circular DNA)

Fig. A bacterial Cell
Antibiotics are used to treat bacterial infections. The bacteria called gram positive bacteria are
susceptible to antibiotics but gram negative bacteria are more resistant to antibiotics.
According to mode of nutrition bacteria are of following type:

260 Blooming Science Book 9

Autotrophic Bacteria

These bacteria can synthesize their food from inorganic substances like higher plants. According
to source of energy they are of two type:

(i) Photoautotropic : use solar energy & have chlorophyll

(ii) Chemoautotropic: This bacteria use inorganic energy sources to synthesize organic
compounds from carbon dioxide. That is , they produce food through chemosynthesis
not from photosynthesis.

Heterotrophic Bacteria

They cannot synthesize their own food. They obtain their food from other organisms. They are
of following types:

(i) Saprophytic Bacteria: They get food from organic remains. e.g. animal excreta, fallen
leaves, meats, jams etc. They breakdown complex organic substance into simple
compounds either anaerobically or aerobically by fermentation, putrefaction or decay.
These bacteria dispose off the dead bodies and organic wastes and also release raw
materials for reutilization. So, they are called nature’s scavangers. e.g. Pseudomonas.

(ii) Symbiotic Bacteria: These bacteria live in mutual beneficial association with other
organisms and share the benefits. e.g. Rhizobium lives in root nodules of legumes, from
which it obtains food and shelter. In return, it helps plants by fixing nitrogen.

(iii) Parasitic Bacteria: They live in contact with other organisms to get organic compounds
for their growth and breakdown the host’s connective tissues, cellulose etc. some parasitic
bacteria cause disease to the organisms called pathogenic bacteria.

Beneficial Effects of Bacteria

Role in Agriculture:

(i) Nature’s Scavenger: They decompose and decay dead plants and animals and clean the
environment.

(ii) Nitrification: Bacteria change ammonium compounds to nitrates which are useful for
leguminous plants.

(iii) Symbiotic Nitrogen Fixation: Some bacteria live symbiotically in the roots of some plants,
fix atmospheric nitrogen and make it available for the plants.

(iv) Manure: Saprophytic bacteria convert farm refuse, dung and other organic waste into
manure.

(v) Gobar gas plant: Bacteria convert animal dung and other organic wastes into manure along
with production of fuel gas.

(vi) Sewage disposal: Organic content of sewage are broken down by bacterial.

Role in Industry

(i) Dairy Industry: Milk is converted into curd, yoghurt, cheese etc. by bacterial.

(ii) Vitamins: Different kinds of vitamins are produced from bacteria. e.g.

Vitamin B12 is made from Bacillus megatherium

Blooming Science Book 9 261

Negative Effects of Bacteria

a. Spoilage of Food: Saprophytic bacteria cause rotting of vegetables, fruits, meats, etc.

b. Diseases: Over 90% of animal disease and 10% of plant diseases are caused by bacteria.
Diplodococcus phenmoniae cause pheumonia, vibrio cholera causes cholera, salmonella
typhi causes typhoid.

c. Denitrification: Some bacteria like thiobacillus and micrococcus convert nitrate into
gaseous nitrogen. Pseudomonas like bacteria decreases fertility of soil.

Control of bacteria

i) By using antibiotic like medicines.

ii) Healthy plants seeds should be used.

iii) Maintaining the environment clean and taking care in personal hygiene.

iv) Person infected with bacterial disease should be taken to hospital.

Fungi

A fungus (plural fungi) is a member of large group of eukyarotic organisms that includes micro-
organism such as yeasts and moulds as well as the more familiar mushrooms. These organisms
are classified as a kingdom-mycota or fungai. It is a large kingdom over 1,00,000 species. This
kingdom is separated from plants, animals and bacteria. One major difference is that fungal cells
have cell wall which contain chitin, whereas plants cell walls contain cellulose. Real fungus
belong to division Eumycota, whereas other fungus (molds) belong to division Maxomycotina.

The branch of biology devoted to the study of fungi is called mycology.

Genetic studies have shown that fungi are more closely related to animals than to plants.

mushroom Mucor

General Characters of Fungi

1) They are eukaryotic organisms.

2) The vegetative body is made of numerous filaments called hyphae. The hyphae form a
tangled mass called mycelium. But some fungi are unicellular eg. yeast.

3) They lack chlorophyll and obtain their food from dead organic matter. They are either
saprophytes or parasites. They hare heterotrophic.

4) Cell wall is made of chitin.

5) Reserve food material in the form of glycogen and oil. Starch is absent.

6) They reproduce by vegetative, asexual and sexual methods.

262 Blooming Science Book 9

Importances and Uses of Fungi
1) Fungi perform an essential role in the decomposition of organic matter and have

fundamental role in nutrient cycling and exchange.
2) Fungi are used as biological pesticides to control weeds, plant diseases and insect pests.
3) Industrially fungus are being used to produce various enzymes, antibiotics, etc. and in

leavening and fermentation of various food products.
4) Fungus like different types of mushrooms are used as direct source of foods.
Harmful effects of fungi
1) Fungi causes skin disease. During monsoon season, leather clothes and shoes, electronic
devices are affected by fungi.
2) It causes high fever and various alleriges to humans.
3) It causes graying disease of maize, burning disease (Daduwa) in potatoes etc.
4) Rhizopus, mucor etc cause food poisoning and serious health problems.
Control measures of fungi
1) By keeping various foods and vegetables in cold and dry place ie in refrigerator.
2) Using chemicals like fungicide.

3) Maintaining proper hygiene.

4) By using salts in fruits and vegetables.

Protozoa

i) Animals which are made up of single cell: i.e. unicellular and cannot be seen by naked
eyes (microscopic).

ii) They are mainly aquatic.
iii) All the vital activities like nutrition, excretion, respiration, etc. are performed within the

same cell.
iv) Locomotion takes place by pseudopodia or flagella or cilia.
v) Excretion takes place through the outer surface or contractive vacuole.
vi) Reproduction takes place asexually by binary fission and sexually by conjugation. eg.

Amoeba, Paramecium, Plasmodium, Euglena, etc.

Amoeba Paramecium Euglena
Blooming Science Book 9 263

Harmful effects of protozoa

Protozoa can cause several diseases to humans. Some of them are:

1) Amoebiasis / dysentery caused by Entamoeba histolytica.

2) Sleeping sickness is cause by trypanosoma.

3) Malaria is caused by plasmodium.

4) Giardisis etc.

Control measures of protozoa

1) By avoiding the food of hawker’s shops.

2) By maintaining the proper personal hygiene.

3) By controlling the insects like flies and mosquitoes.

4) Keeping the distance with infected persons.

Main Points to Remember

1. Bacteria, virus, fungi and protozoa are micro-organisms.
2. Viruses are known as obligatory parasites as they are fully dependent on the living organisms

for multiplication.
3. Viruses show both the living and non-living natures.
4. Viruses are generally regarded to be organisms because they are capable of attaching to

proper host cell to begin infection and self-replication.
5. Virus cause the diseases like Common cold, Mumps, Measles, Polio, Rabies, AIDS.
6. Bacteria are a large domain of prokaryotic micro-organisms.
7. According to mode of nutrition bacteria are of following type:
Autotrophic Bacteria
Heterotrophic Bacteria
8. A fungus (plural fungi) is a member of large group of eukyarotic organisms that includes

micro-organism such as yeasts and moulds as well as the more familiar mushrooms.
9. Animals which are made up of single cell: i.e. unicellular and cannot be seen by naked

eyes (microscopic).
10. Amoeba cause dysentery and malarial parasites cause malarial fever.

PRO J ECTWORK

Visit a mushroom farm in your locality. Observe the process of growth and various parts.
Make a report including the advantages of mushroom and discuss in your class.

264 Blooming Science Book 9

Exercise

1. Choose the correct answer from the given alternatives.

a. Plants found on desert are called.

a. Hydrophytes b. xeric c. Xerophytes d. Mesophytes

b. The study of micro organism is called.

a. bacteriology b. microbiology c. microbes d. mycology

c. ................. are obligatory parasites.

a. bacteria b. virus c. protozoans d. all of above

d. Those animal which are adopted for running.

a. Cursorial animal b. fossorial animal c. aboreial animal d. aerial animal

e. Which of the following is an obligatory parasite?

a. protozoa b. bacteria c. virus d. all of the above

2. Answer the following questions:

a. What are micro-organisms?

b. Write types of bacteria. Write its advantages and harmful effects.

c. Name the diseases caused by virus. Mention the importance of virus and its harmful
effects.

d. Distinguish between bacteria and virus.

e. Write the importance of fungi. Mention the harmful effects of it.

h. What are the control measures of bacteria?

i. Draw a labelled diagram of virus.

j. What are called protozoans? Write its harmful effects.

3. Write notes on the structure of following organisms.

a. Bacteria b. Fungi c. Amoeba d. Virus

4. Give reasons:

a. Bacteria are both useful and harmful.

b. Virus is called obligatory parasite.

c. Amoeba is called protozoa.

d. Fungi is called saprophyte.

Blooming Science Book 9 265

Chapter BODY SYSTEMS

18

Learning Outcomes Estimated Periods: 4+1

On the completion of this unit, the students will be able to:
• describe relationship between cell, tissue organ and system.
• describe types and position of plant tissue.
• tell functions of human skeletal system.
• make a list and classify various bones of human skeleton.
• introduce and describe the importance of respiratory system and excretory system.

Cell is the basic unit of life. All living things are composed of cells. An unicellular organism is
composed of only one cell whereas a multicellular organism is composed of many cells. Life
processes like respiration, excretion, reproduction, etc. are performed within the single cell in
case of unicellular organisms, but there are separate groups of cells responsible for separated
functions in case of multicellular organisms. Such a group of similar cells is called a tissue.
Thus a tissue may be defined as a collection of similar cells having the same structure adapted to
performance of the same function or set of functions. The cells have their shape and size depending
on their functions. The cells or a tissue follow the same laws of growth and development. Some
examples of animal tissue are epithelium, muscle, bone, blood and nerve. Similarly meristem,
parenchyama, xylem and phloem are some examples of plant tissues.

An English scientist Robert Hooke coined the word cell in 1665 AD, in his book named
Micrographia. When he observed a very thin section of cork under self constructed compound
microscope, he found that the cork was composed of many small boxes like components, which
were named by him as cells.

Anton Van Leewnhoek, a Duch microscopist observed firstly the green pigment of plants under
microscope. Now they are termed as chloroplasts. Bacteria and some unicellular organisms
were also observed by him. In 1831 AD Robert Brown observed nucleus in plant cells. German
botanist Schleiden and German zoologist Theodar Schwann formulated “Cell Theory” in 1839
AD on the basis of their independent studies of the plant and animal tissues.

Relationship between Cell, Tissue, Organ and System

Unicellular organisms carry out all the vital life activities such as growth, respiration, food
assimilation, excretion and reproduction within a cell. Such animals show cellular organization.
A tissue is defined as the collection of similar cells having the same structure adapted to the
performance of the same function or set of functions. When cells are organized to form tissue, it
is called tissue level of organization. Animal tissues are muscle, blood, bone, nerve, epithelium,
etc. Plant tissues are meristem, parenchyma, xylem, phloem, etc.

Tissues in a group constitute an organ. Some organs perform only one particular function heart-
blood circulation whereas other perform more than one function [kidney-removal of nitrogenous
wastes as well as regulates water balance in body]. Animal organs are lung, kidney, liver, etc.
Plant organs are root, leaf, stem, flower etc.

266 Blooming Science Book 9

Different organs work in combined and coordinated way. Thus forming a system. For example
digestive, circulatory, excretory, etc. Digestive system includes mouth, pharynx, oesophagus,
gizzard, stomach and intestine - its main function is digestion of food materials and absorption
of nutrients.

The circulatory system supplies food and oxygen to the body cells. Blood removes the metabolic
wastes from the tissue to the excretory organs from where they are expelled.

There are several functions being carried out in the body of a living organism. There functions
are carried out by different types of tissues in the group. Tissues in the group constitute an organ.
An organ is generally responsible for a particular function. However there are also some organs
which carry out more than one function. As for example, the cardiac tissues are responsible for
circulation of blood throughout the body where as tissues of kidney help in removal of excretory
materials as well as control the amount of water in our body. Lungs, kidneys and liver are some
examples of animal organs. Similarly root, leaf, flower, etc. are plant organs.

The system found in the human body, their organs, tissues and main function are
given in the following table.

S.N System Organs Types of Tissue Functions

1. Digestive Alimentary canal, Columnar epithelium, To make the food
System
Liver, pancreas involuntary muscular soluble and absorb

these.

2. Respiratory Lungs Cubical and pavement To exchange gases
System
epithelium and to make energy

by the oxidation of

food.

3. Circulatory Heart, blood, blood Connective tissue To make transport

System vessels involuntary muscle and various materials in

pavement epithelium body.

4. Excretory Kidney, liver. skin, Cubical and pavement To remove the
System
large, intestine, etc. epithelium materials wastes.

5. Nervous Brain, Spinal cord Nervous tissue To passes impulses
System and to show the
response

6. Skeletal Bones Connective tissue To make the frame
System work of body and
move it.

7. Reproductive Overy, testes Cubical, columnar To produce the young
system epithelium ones.

Plant Tissue

In the simplest plants, the whole plant body is made up of either a single cell or a colony of cells.
Since plants of this kind are usually found in water, each cell is in direct contact with water and
minerals. In advanced vascular plants, a division of labour occurs among different kinds of cells.
Cells of plants exhibit great variation in size and structure. A group of plant cells performing
essentially the same function and common to similar structure is called a plant tissue.

Blooming Science Book 9 267

Plants are able to produce new tissues throughout their life. Plant tissues can be classified on the
basis of characters like nature of cells, origin and method of development, position in plant body
etc. On the basis of the stages of development, plant tissues are divided into two types:

1. Meristematic tissue Scan for practical experiment
2. Permanent tissue

1. Meristematic Tissue

The group of young cells which have the capacity of active cell division visit: csp.codes/c09e22
is called meristem. The cells of this tissue are of different shapes with
big nucleus, thin cell wall and dense cytoplasm. It does not have
intercellular space. The vacuoles are few and small in size. The major
function of this tissue is to help in growth.

On the basis of origin, the meristems are classified as: Primary meristems and Secondary meristems.

a. Primary Meristems: Those meristems, which are derived directly from the meristems of
embryo and persist throughout the life of the plants, are called primary meristems. They are
responsible for the primary growth and lie mainly on the apices of stems and roots.

b. Secondary Meristems: Those meristems, which are formed as new meristems in permanent
cells by re-differentation, are called secondary meristems. Secondary meristems are usually
lateral in position and are responsible for increasing the diameter of plant organ.

On the basis of location in the plant body, the meristems are divided in three types. They are
apical, lateral and intercalary meristems.

i) Apical Meristems: These meristems are primary meristems, present, in the growing points i.e.
apices of root and shoot. Their activity mainly helps in the increase in length.

ii) Lateral Meristems: These meristems are embedded in the Apical
meristem
permanent tissues and are laterally located. e.g. cork Intercalary
cambium of roots and stems. Their acitivity helps in the
increase in girth of diameter of the plant. meristem

iii) Intercalary Meristems: These meristems are located Lateral
between regions of permanent tissues beneath the apical meristem
meristem. It is also known as the part of apical meristem.
It is found at the base of leaves above the nodes. The
activity of intercalary meristems is to increase the length
of axis in which they are restricted.

2. Permanent Tissue

In permanent tissues growth is ceased, at least temporarily. Nucleus
They are made up of cells that have lost the power of division
and are differentiation to carry out various functions. The Intercellular
cells may be living or dead. It may be primary or secondary. space
Primary permanent tissues are derived from the apical

268 Blooming Science Book 9

meristems whereas the secondary permanent tissues are derived from the lateral meristems. The
permanent tissues are of three types:

1. Simple permanent tissue

2. Complex permanent tissue and

3. Special tissue

1. Simple Permanent Tissue: Simple permanent tissue consists of similar cells of only one
type. The tissues are concerned with manufactured and storage of food and to provide the
basis of structure, it is of following three types:

i) Parenchyma

ii) Collecnchyma

iii) Sclerenchyma

i) Parenchyma: Parenchymatous tissues are made up of thin walled cells,
which are usually living. The cells are usually oval or spherical. Those
parenchyma cells which contain chloroplast are called chlorenchyma.
The tissues, which possess air spaces in between the cells are called Parenchyma
aerenchyma. Parenchymatous cells form a large part of cortex, pith, mesophyll
cells of leaves, fruit pulp and endosperms of seeds. The main function of parenchyma is to
manufacture and store the food.

ii) Collenchyma: Collenchyma has thick cell wall with an extra deposition Collenchyma
of cellulose at the corners of the cells. It is present in outer regions of
cortex e.g. stem, midrib of leaves, petioles, etc., but it is absent in roots
and monocot plant. The major functions of this tissue are:

a. It provides support and elasticity. It is found due to thickening.

b. Chloroplast contains collenchymas which is responsible for photosynthesis.

c. It resists the tearing effect of the wind on the leaves (due to presence along the margin).

iii) Sclerenchyma: Sclerenchyma consists of dead cells with thick cell Sclerenchyma
walls. They are mainly responsible for providing strength and mechanical
support. It includes two types of cells. They are fibres and sclereids. Fibres
are commonly found in stems. Sclereids are usually found in phloem, fruit
walls and in the pulp of fruits and seeds. They form a layer in the cortex
below the epidermis of stems of roots. They also occur in xylem and
phloem. The major functions of this tissue are:

Functions:
a. Fibres are mainly responsible for providing mechanical strength where they are found.
b. Sclereids provide grittiness in the pulp of many fruits.
c. Sclerenchyma in leaves provides rigidity and saves it from collapsing.
d. It saves the plant from various environmental forces like strong wind, etc.

Blooming Science Book 9 269

2. Complex Permanent Tissue: Complex permanent tissues are made up of different types of
cells. The conducting region of a plant is made up this tissue thus it is also called conduction tissues
or vascular tissue. The most important complex tissues are xylem and phloem.

i) Xylem: Xylem is also called wood and it forms the bulk of the roots and stems
of vascular plants. It is made up of four kinds of cells. They are trachides,
vessels, xylem fibres and xylem parenchyma. These are found in the inner
portions of root, stem, leaf and other hard parts of a plant. The major cells of this
tissue are dead. It conducts water and mineral nutrients from the root to the
leaves.

ii) Phloem: Pholem is a complex permanent tissue in which tubes are composed of
living cells. It is made up of four type of cells. They are sieve tubes, campanion cells,
phloem fibres and phloem parenchyma. Major cells of this tissue are living. It is
mainly responsible for transportation of food.

3. Special Permanent Tissue: The tissues, which are concerned with the secretion of materials
like gums, resins, oils, nectar, latex and other substances, are called special tissues or
secretary tissues. The well organized secretary structures are called glands. They are further
subdivided into two groups: lactiferous tissues and glandular tissue.

Lactiferous tissues are thin walled, elongated and branched ducts lactiferous tissue
which contains a milky juice called latex (an emulsion of various
metabolic products in a matrix of watery base). The ducts are irregularly
distributedinparenchymatouscells.Theyaresupposedtoberesponsible
for food storage or waste products.

The glandular tissue is consists of isolated cells or small groups of cells. They may be
internal or external and are of various kinds. Those glands which secrete digestive enzymes
called digestive glands found in many insectivorous plants like Drosera, Utricularia, etc.,
and those which secrete nectar, known as nectaries (e.g., in flower).

Differences between Xylem and Phloem

Xylem Phloem

1. Conducting tissue from roots to leaves. 1. Conducting tissue from leaves to other
parts of plant body.

2. Commonly called wood, consists of four 2. Four different types of living cells - sieve

types of dead cells - tracheids, vessels, tube, companion cells, phloem fibre and

wood fibre and wood parenchyma. phloem parenchyma.

3. Conduction of water and mineral from 3. Conduction of food from leaves to various

root to the plant parts. parts.

4. Found in root, stem and leaf. 4. Found in root, stem and leaf.

5. Mechanical strength and support. 5. Mechanical strength and support.

6. Storage of food, water and minerals.. 6. Storage of food.

270 Blooming Science Book 9

Differences between Meristematic and Permanent Tissues

S.N. Meristematic Tissues S.N. Permanent Tissues

1. The cells divide throughout their life. 1. The cells do not divide.

2. Cells are living with thin wall. 2. The cells are living or dead with thick
wall.

3. They are localized in the growing 3. They are found throughout the plant

regions. body except growing regions.

4. They support the growth and form 4. They perform vital and mechanical

permanent tissues. functions of the plant body.

Skeletal System in Human Body

The combination of bones to form skeleton is called skeletal system. In human being, there are
altogether 206 pieces of bones and in baby, there are 266 pieces of bones including 33 vertebrae.
Bone is a living tissue, made up of living cells, blood vessels and nerves. Skeletal system provides
supporting framework of our body. It also helps in movement. Bone contains non-living calcium
salt which makes it hard, rigid and strong. Bones have different shapes. Bones of skull and ribs
are flat. Bones of hands and legs are long. Bones of wrist and knee are cubical. Bone of vertebral
column are irregular.

Majority of living beings have specific shape and size. The skeleton provides the supporting
frame work of the body to give proper shape and size and protects the internal organs. The
skeletal system may be exoskeleton (outer skeleton) or endoskeleton (inner skeleton). In
exoskeleton, hard structures like shells, spicules, calcareous plates covers the body from outside,
Endoskeleton are formed inside the body which are made of bones and cartilage.

Bone is a hard tough connective tissue which consist different kinds of calcium salts like calcium
phosphate, calcium carbonate calcium fluoride etc. It is also made of living cells oestocytes,
nerves and blood vessels.

Cartilage is a soft flexible connective tissue which is found at the end of long bones. Ear pinnae,
nose etc. It acts as a shock absorber.

The skeletal system is a group of different types of bones and cartilages which provides supporting
frame work of the body and protects the internal organs.

Shape of bone depends upon its function. Being soft, cartilage can grow from inside and complex
shapes can be formed. Firstly, tiny cartilaginous model is formed and this shape is preserved and
it is replaced with bone. Cartilage is found in the nose, ear lobe, trachea, bronchioles (in the form
of rings), in between vertebrae and end of long bones.

Structure of a Bone

Bone is made up of two types of skeletal tissue. The outer is compact bone which is hard made
of salts of calcium. The inner is spongy bone which contains several columns filled with bone
marrow. Due to presence of salts of calcium, the bone is hard. If bone is dipped in acid for few
days, the hardness of the bone will be lost. It can be bent easily minerals like calcium phosphate
present in the bone dissolves with acid leaving behind the fibrous organic matter. The skeletal
system is a group of different types of bones and cartilages which provides the supporting
framework of the body and protects the internal organs.

Blooming Science Book 9 271

Functions of Skeletal System

The general functions of a skeleton are as follows:

1. Support: The skeleton provides a rigid framework for the body and helps to maintain the
shape of the body.

2. Protection: The skeleton protects the delicate internal
organs of the body. For example, in man, the cranium
protects the brain and the sense organ of sight, smell and
hearing; the vertebral column protects the spinal cord;
and the ribs and sternum protect the heart, lungs and large
blood vessels.

3. Locomotion: The skeleton serves as the basis for the
attachment of muscles. Parts of the skeleton act as levers
on which the muscles can pull.

4. Storage: The skeleton serves as a store house of
minerals such as calcium and phosphorous.
5. Formation of blood: The bone marrow of long bones
produces red blood cells and white blood cells.

Bones of Skeleton

Bones of Human Body

Axial-bones of middle part of our body Appendicular-side bones of body
(skull, chest and vertebral column) (hand, leg, shoulder and pelvis)

Upper extrimity Lower extrimity

Axial Skeleton (80) Pevic gird(2) Hind
Pectoral girdle(4) Fore Limbs(60) limbs(60)

Skull (22) Trunk (58)

Cranium (8) Facial (14) Vertebral column (33) Sternum and ribs (25)

Cervical (7) Thoracic (12) Lumbar (5) Sacral (5) Coccyx (4)
272 Blooming Science Book 9

A. The Axial Skeleton

It consists of the skull, vertebral column and thorax (ribs and sternum).

1. Skull

The bony framework of the head is called skull. The skull consists of the cranium and the
face.

(a) Cranium: The cranium consists of eight flat bones which are tightly interlocked forming a

series of immovable joints. Besides enclosing and protecting the brains, it protects the

olfactory organs, middle and inner ear and the eyes. Frontal

i) Frontal bone (1): This is the bone of the Parietal Sphenoid

forehead. It forms part of the orbital Zygomatic
Maxilla
cavities and the prominent ridges above Occipital
the eyes.

ii) Parietal bones (2): These bones form Mandible
the sides and roof of the skull.
Temporal Fig: Skull

iii) Temporal bones (2): These bones lieone in each side of the head.

iv) Ethmoid bone (1): The ethmoid bone occupies the anterior part of the base of the skull. It
helps to form the orbital cavity, the nasal, septum and lateral wall of the nasal cavity.

v) Sphenoid bone (1): This bone occupies the middle portion at the base of the skull. It lies in
front of the temporal bone.

Scan for practical experiment

vi) Occipital bone (1): This bone forms the back of the head and part
of the base of the skull.

(b) Facial Bone: The front portion of the skull is the face. It consists
of fourteen bones. The upper and the lower jaws are formed by
some of the bones of the face. The bones of the face are:

i) Mandible (1): It is the only movable bone of the skull. It forms visit: csp.codes/c09e21
movable joint with the cranium.

ii) Maxilla (2): It is made up of two fused maxillae and it forms the upper jaw.

iii) Zygomatic (2): These bones form the prominence of the cheeks. So, it is also called the
cheek bones.

iv) Nasal (2): These are two small flat bones which form the bridge of the nose.

v) Lacrimal bone (2): These two small bones are posterior and lateral to the nasal bones and
form the part of the medial walls or the orbital cavities.

vi) Vomer (1): The vomer is a thin flat bone which forms the main part of the nasal septum.

vii) Palatine (2): These are two L shaped bones which form the back part of the hard plate.

viii) Inferior nasal conchae (2): These bones form a part of the lateral wall of the nasal cavity.

Blooming Science Book 9 273

2. The Vertebral Column Cervical
vertebrae
The vertebral column commonly known as the back bone is the
main axis of the body. It is made up of a linear series of bones called Thoracic
vertebrae. The vertebrae are placed end to end and are separated by vertebrae
internal vertebral discs which are cushioning pads of fibrous cartilage.
The vertebral columns give protection to the spinal cord. They are Lumbar
usually 33 in number. Due to the fusion of the lower part of the column, vertebrae
it is found that there are 26 separate bones in the adult. These vertebrae
are basically of five different types which are named according to the Sacral
region they occupy. These are as follows: vertebrae
Coccygeal
(a) Cervical Vertebrae: They are seven in number and are located in vertebrae
the neck. The first cervical vertebra is called the atlas which supports Fig: Vertebral column
the skull and allows a nodding movement. The second cervical
vertebra is called the axis which allow skull rotation.

(b) Thoracic Vertebrae: They are twelve in number and are located in the thorax. They connect
with ribs and the sternum, forming a thoracic cage. They protect the heart and lungs and
allow the respiratory movement.

(c) Lumbar Vertebrae: They are five in number. The lumbar vertebra are the largest vertebrae.
They are heavier than the other vertebrae to support more weight. These are located in the
abdomen.

(d) Sacral Vertebrae: These are five separate bones in the child. In adult, they fuse together to
form a large bone called the sacrum. These are located in the hip region.

(e) Coccyx: This consists of four terminal vertebrae fused to form a very small triangular bone.
These are located in the tail region.

The vertebrae are held together by the ligaments. Ligaments consist of elastic yellow fibres.
They binds the bones together and provide slight movement to them.

Functions of Vertebral Column:

The general functions of vertebral column are as follows:

i) It provides protection to spinal cord.

ii) It gives support to different body organs.

iii) The inter vertebral discs or a pad of cartilage between the vertebrae act as shock absorbers.

iv) The head moves on the support of the first vertebra.

v) The surface of transverse process provides surface for muscle attachment.

274 Blooming Science Book 9

3. Thorax (Ribs and Sternum)

The bones of the thorax form a cone-shaped Vertebral True ribs
protective cage and protect the vital organs like column
heart lungs etc. The thorax consists of two parts:
sternum and ribs. Sternum

(a) Sternum (breast bone): Sternum is

a flat narrow bone located in the middle of

the front part of the chest. Floating False ribs

(b) Ribs: There are twelve pairs of ribs which ribs

are long flat and curved. The thoracic vertebrae at Fig: Thorax
the dorsal side, the sternum on the ventral side and

the ribs on the other sides together form thorax. Each rib articulates with vertebra by double

head and is attached to sternum by flexible cartilage. The first seven pairs are true ribs which

are directly attached to the sternum; the next three pairs indirectly connected by the sternum are

called false ribs; and the last two pairs (eleventh and twelfth) not attached to the sternum are

called floating ribs.

Comparison of True Ribs, False Ribs and Floating Ribs

S.N. True Ribs False Ribs Floating Ribs

1. There are seven pairs of There are three pairs of There are two pairs of

true ribs (1 to 7). false ribs (8-10) floating ribs (11-12)

2. These ribs have a direct These ribs do not attach These ribs do not attach
anterior attachment to the directly to the sternum. to the sternum. They are
sternum. Their cartilage fuse attached only to the thoracic
together before joining vertebrae.
with the sternum.

B. The Appendicular Skeleton

It consists of pectoral and pelvic girdles, and bones of the limbs. This skeleton is divided into
two groups: the upper and the lower. The upper group consist of the pectoral girdle with forearms
and the lower group consists of pelvic girdle with the hind limbs. Girdles help to articulate the
limb ones to the axial skeleton.

I) The pectoral girdle and bones of fore arms: The girdle that support the bones of arm is
called pectoral girdle. The pectoral or shoulder girdle is made up of a clavicle or collar bone and
a flat scapula or shoulder blade. Each shoulder girdle consists of one clavicle. The scapula is a
flat triangular bone in each shoulder girdle.

The pectoral girdle is attached by muscles and tendons to the thoracic vertebrae. The
connection is a loose one acting as a shock absorber to reduce upthrust received by the forelimbs
when they strike the ground.

Blooming Science Book 9 275

Each forearm consists of the following bones:

(a) Humerus: In the upper arm, there is only one bone. It is called Clavicle
humerus. It is a long bone with ball shaped head that exactly fits Scapula
into glenoid cavity in the pectoral girdle.

(b) Radius and Ulna: These two bones which are firmly attached to Humerus
each other. The small and broad bone towards the thumb is called
radius. The narrow bone that is placed towards the little finger is
called ulna.

(c) Carpal or Wrist: There are eight carpal bones in each hand Ulna
arranged in two rows (each of four) in the wrist. These bones are Radius
closely fitted together.
Carpals
(d) Metacarpal: The palm consists of five long bones called Metacarpals
metacarpal. These bones extend from carpals to phalanges. Phalanges
Fig: Fore arm
(e) Phalanges: The fingers consist of 14 small bones called
phalanges.

II) The pelvic girdle with hind limb: The girdle into which the bones of legs are fitted in it is
called pelvic girdle. The pelvic girdle is a strong structure which supports the abdominal organs.
The shape of the female pelvis allow the passage of the baby during child birth. The female pelvis
has lighter bone. The two wide bones connected to the thigh bone and spine are called pelvic
girdle. Each pelvic girdle consists of three fused bones, the ilium, ischium and pubis. The pelvic
girdle in female is wider than male of the development of baby inside uterus and for delivery.
It supports skeleton of body and protects stomach, urinary bladder, intestine and reproductive
organs.

Each hind limb consists of following bones Femur

Pelvis
(a) Femur or Thigh Bone: The bone present in the thigh is
the longest and strongest bone of the body which is known as
femur. The upper end of each femur bone articulates with the
actabulum at the hip. The lower end articulates with the tibia
and patella to form the knee joint.

(b) Patella or Knee Cap: This is roughly triangular Patella Fibula
shaped bone found at the knee. Tibia

(c) Tibia and Fibula: These are two bones of the lower
leg. Tibia is the broad bone towards the great toe of
the foot. Fibula is the bone towards the little toe of
the foot.

(d) Tarsals: There are seven tarsal bones which form Tarsal Metatarsal
ankle of the foot. They are rounded and arranged in
three rows. Phalanges
Fig: Pelvic with hindlimb

276 Blooming Science Book 9

(e) Metatarsals: There are five metatarsal bones in each. They are long and straight bones of
foot.

(f) Phalanges: There are 14 phalanges in the toes, two in the great toes and three in each of the
remaining toes.

A. Digestive System

Digestive system is the collective name used to describe the alimentary canal, some accessory
organs and a variety of digestive processes which take place at different levels in the canal to
prepare food eaten in the diet for absorption. The food that we eat cannot be absorbed as it is. The
complex digestive process gradually simplifies the food eaten until they are in a form suitable for
absorption. Thus, we can say that the digestive system deals with the reception of food and the
preparation of it, for assimilation by the body.

The digestive system consists of all the organs which are related to chewing, swallowing,
digesting and absorbing the food and finally discarding the unwanted food. The digestive process
begins at the mouth, passes through the thorax, abdomen and pelvis, and at the anus. After the
foods are absorbed, the nutrient materials are used in the synthesis of the constituents of the body.

The activities in the digestive system can be grouped under four main headings:

i. Ingestion: taking food into the alimentary tract.

ii. Digestion: the mechanical and chemical process which break down and gradually simplifies
the food for the absorption.

iii. Absorption: the process by which nutrient materials are used for the body building and
development.

iv. Elimination: food substances which have been eaten but could not be digested and absorbed
are excreted by the bowel as faeces.

The following are the organs and glands which take part in the digestion of food. Those organs
are as follows:

1. Mouth 2. Pharynx 3. Oesophagus 4. Stomach

5. Small intestine 6. Large intestine 7.Rectum

The glands are as follows:

1. Salivary glands 2. Gastric glands 3. Pancreas 4. Liver

5. Intestinal glands

Digestion of food: The food we eat is complex chemical compound. That cannot release energy
easily. That food should be changed to simple organic compound in order to get energy easily.

The process by which the complex compound of the food is changed to simple compound to
enable it for absorption and emit energy easily, is called digestion of food.

Alimentary Canal

The organs of digestive system are attached with one after another from mouth to rectum and
form about 8 to 10 metres long tube. This tube is called alimentary canal.

Blooming Science Book 9 277

Structure and functions of digestive system:

a. Mouth or Oral Cavity

Our mouth possesses teeth, tongue and

salivary glands. When food is taken into Mouth
Salivary glands
the mouth,the teeth come into action. They
break the food into small fragments making

it easier for the enzymes to act on them. Oesophagus
During this action, saliva the juice secreted

from salivary glands, mixes with the food.The

enzyme ptyalin of saliva, acts on starchin the

food and convertsitinto simpler substance Liver Stomach
called maltose. The food is rolled by the tongue Gall bladder
into a ball and is swallowed down the throat Pancreas
Small
into the oesophagus. Large intestine

b. Pharynx and Oesophagus intestine

The pharynx helps us in swallowing the eaten Appendix
food. It prevents food from going into the
windpipe. Oesophagus is a muscular tube that Rectum
transports food from mouth to stomach.

c. Stomach

Stomach is a bag like organ which is made of muscular walls. It is attached

withduodenum, the upper part of the small intestine. It has several gastric

glands which secrete gastric juice. This juice contains enzymes named

Pepsin and Rennin. It has a little amount of hydrochloric acid also. ?DO

The food first mixes well with the gastric juice Chewing breads and beaten You
and is then acted on by Pepsin and Rennin. rice(chiura) for long time Know
The hydrochloric acid provides a medium

in which the enzymes act. It also serves as an converts the carbohydrates

antiseptic to kill certain bacteria present in the stored in them into glucose

food. which gives us sweet taste

Pepsin breaks protein into peptone and proteoses. Rennin separates fats from milk. It clots the
milk and forms casein.

The food remains in the stomach about 4 hours. After the food is mixed with the acid and
digestive juice, it takes the form of a thick liquid like paste called chyme.

d. Small intestine

The upper part of the small intestine is called duodenum where the
food gets two kinds of digestive juices: bile from the liver and
pancreatic juice frompancreas. Pancreatic juicecontains 3 enzymes
named lipase, amylase and tripsin. Bile is greenish yellow liquid
which is manufactured in the liver. It is alkaline and helps to

278 Blooming Science Book 9

neutralize the acidity of the food which comes to duodenum from stomach. Bile also helps to
emulsify the fat of the food.

When bile and pancreatic juice mix with the food, tripsin begins to break proteins and
peptide to amino acids. At the same time, amylase converts starch remaining in the food to
maltose. Lipases also acts on oil and fat and converts them into fatty acid and glycerol.
The middle part of small intestine is called Jejunum.

e. Ileum

The lower part of the small intestine is called ileum. It has many intestinal glands which
produce intestinal juice. That juice also contains three kinds of enzymes: amino peptidages,
disaccharidase and lipase.

The special feature of ileum is that it contains millions of finger like projection called Villi.
They have a network of capillaries so that the simple molecules produced by digestion
(sugars and amino acids) can quickly pass into the bloodstream.

In ileum, the enzyme disaccharidase acts on starch and converts it into glucose. The amino
peptidages acts on protein and peptides and converts them into soluble amino acids. The
lipase reacts with the molecules of fat and changes them into molecules of glycerol and
fatty acid. Later on, the digested food is absorbed by villi to mix it into the bloodstream.

f. Large intestine

The rest part of the food comes into the large intestine from ileum. The
large intestine is only 1.5m long while the small intestine is 5 to 6 metres
long. But the large intestine is thicker than the small intestine.

The large intestine consists of the following parts: Large intestine

i. Caecum ii. Ascending colon iii. Transverse
colon

iv. Descending colon v. Sigmoid vi. Rectum

The large intestine begins from caecum. It ascends towards the liver, transverses towards the
spleen and then descends with a bend at sigmoid and ends at anus. Its portion between the
sigmoid and anus is called rectum.

The large intestine does not take part in the digestion of food. But the absorption of water,
salts etc. take place in it. The remaining part of the food which is harmful for our body is
called faeces. That faeces is collected in the rectum till it is ejected.

The following table gives the description of digestion in a human body.

Table of Digestion

Parts of the Digestive Digestive Enzymes Substances Substances
Alimentary Canal glands juices acted upon produced
1. Mouth Ptyalin
Salivary Saliva Starch Maltose
2. Stomach glands Rennin
Gastric Pepsin Milk Casein
Gastric juice Protein Peptide
glands

Blooming Science Book 9 279

3. Duodenum Pancreas Pancreatic Lipase Fat Fatty acid and
4. Small intestine Liver juice Amylase glycerol
Bile Trypsin Starch Maltose
Intestnal Protein Amino acid
glands Intestinal Peptidases Protein and Amino acid
juice peptide
Disaccharidase Sugar and Glucose Fatty
Lipase maltose acid and
Fat glycerol

B. Respiration System

We have been breathing continuously day
and night by birth. All creatures of the Nose
world are involved in breathing to keep them

alive. The process of breathing in oxygen

to burn digested food in tissues to give Neck

energy and breathing out carbon dioxide is

called respiration. All plants and animals use

oxygen and give out carbon dioxide during Lungs

respiration. The following organs take part

in respiration:

1. Nose 2. Pharynx

3. Larynx 4. Trachea

5. Bronchus 6. Lungs

7. Diaphragm.

1. Nose Olfactory nerve Frontal Olfactory Olfactory
endings and nerves sinus bulb tract
Our nose is the outer organ of respiratory
system. We breathe in and breathe out Inferior concha
through our nose. There are hairs in nostrils. Middle concha
These hairs act as a screen to keep the Superior concha
dust and other particles in the air away from
entering the lungs. They are the first Fig: structure of nose
defense against foreign matter. The space
inside the nose beyond nostrils is the nasal cavity.
This part of the nose works for cleaning the
air and preparing it for the lungs. Lungs need
warm, moist and clean air if they are going
to supply oxygen to the body. The channel of the
nasal cavity warms and moistens the air.

280 Blooming Science Book 9

2. Pharynx

After the air has been warmed, moistened and roughly cleaned, it enters into pharynx.
The pharynx is divided into two tubes. One of them is called wind-pipe and the other is
food-pipe. The breathed air passes through the wind-pipe.

3. Larynx

The wind-pipe is called larynx also. There is a leaflike piece of cartilage called epiglottis
attached to the top of the larynx. As soon as we swallow the food, the epiglottis comes
down quickly to cover the opening of the larynx. When we breathe, it lifts up and allows
the air to pass through.

4. Trachea and Bronchus

Trachea continues below the voice-box with rings of cartilage which keeps it in definite
shape and save it from collapsing. The lower part of trachea is divided into two tubes,
one going to each lung. These tubes are called bronchi. Each of them continues to divide
until it has many branches. Each branch ends into tiny air sacs. Each contains millions
of air sacs.

5. The Lungs

Each branch of bronchi is attached with a small bag like organ

called lung. Thus there are two lungs in our body. They are

well-protected behind muscles and lie within the rib-

cage. Each lung is covered by a lining that produces a

watery fluid that keeps the lungs moist on outside. They do

not scrape against the chest-wall as they expand. The lungs are

made of elastic tissues and look like soft, wet sponges. The lungs

of newly born child are pink in colour A healthy adult person’s lungs ?DOYou
but they slowly turn to light grey as he grows have about 700 million aveoli. Know
older. The lungs expand when they receive
air and contract when they release air. This is

why our chest goes up and down.

The right lung is shorter, wider and larger while the left lung is longer, narrower and
smaller. The right lung has 3 lobes while the left lung has 2 lobes only.

6. Diaphragm

Diaphragm is the main organ of the respiratory system. It is made of muscles only. This
thin muscles is arched across the width of the body. It separate the chest-cavity from the
abdominal cavity.

Process of Respiration

T here are intercostals muscles between our ribs which help in raising the rib-cage upward. When
we inhale, these intercostals muscles contract and the diaphragm goes down. As for the result, he
chest cavity becomes larger. As the volume inside the chest increases, air rushes in and the tissues
of lungs expand in all directions. This is called inspiration. Air is forced out of the lungs when

Blooming Science Book 9 281

the ribs and the diaphragm return to the resting position. This is called expiration. While inhaling
fresh air, exchange of carbon dioxide and oxygen takes place in the lungs. As the blood passes
through the lungs, it receives a fresh supply of oxygen and it unloads the carbon dioxide that is
brought back from the cells. The carbon dioxide is carried away with the air that leaves the lungs.
The pure blood carries oxygen to cells for burning digested food present in the cells of the body.
Carbon dioxide emits from cells due to burning of the food there. Exchange of carbon dioxide
from cells to the blood-vessels and oxygen from blood-vessels to cells takes place day and night.
The respiration gives off energy to our body to keep it alive. That energy is used in the formation
of new tissues, reconstruction of old tissues, expanding and contracting muscles etc. This energy
is also used in the formation of protein, enzyme, harmone etc. in our body.

Cause of sneeze

What makes you sneeze or cough? Mucus membranes are very delicate and sensitive. Anything
irritating them causes the reparatory muscles to contract very strongly to get the substance out
and you sneeze.

How are the lungs spoilt when we smoke cigarette?

Air-sacs of the lungs are filled with smoke when we smoke cigarette. These air-sacs are filled
with soot as well as the rafters of the kitchen room become black with sooth. As for the result
there air-sacs do not get fresh air and it causes decay of the lungs.

Human Excretory System

Introduction

Our body takes food, water and air, But only a part of them are used in our body. The rest part of
these things come out of our body as a waste product. These waste products come out of our body
as sweat, urine and impure air. The skin excretes sweat, the kidney excretes urine, the rectum
excretes stool and lungs excrete impure air. Expulsion of waste products from our body is called
excretion. The group of organs which take part in excretion is called excretory system.

Excretion of Sweat from Skin

The skin of our body contains sweat-glands. These glands secret sweat which contains water,
salt and urea etc. The skin keeps off the waste products of the body through perspiration. It is
the process of expelling sweat from the skin. There are millions of pores in our skin. The sweat
comes off the skin through these pores. Perspiration maintains the constant temperature of the
body. During summer and in the moments of vigorous manual labour, a great deal of heat is
generated in the body but it does not get overheated by its own heat because the excessive heat
is lost through perspiration.

Excretion of Carbon dioxide

The work of excreting carbon dioxide is done by the lungs. This carbon dioxide gas is formed
during respiration which holds in the cells of our body. This gas reaches the lungs along with the
blood and comes off them by expiration of breathing.

282 Blooming Science Book 9

Excretion of wastes from the Intestine

Fruits and vegetables have fibre in them that are not broken down by digestive juices. These
fibres pass through the small intestine into the large intestine. The left-over food materials that
move into the large intestine usually stay there for a few hours before they leave the body. The
materials stayed in the large intestine is called faeces. The lower part of the large intestine is
called rectum and its outlet is called anus. When the faeces move into the rectum and stay there
for a long time, certainly nerves tell the person it is time for the bowel to be emptied.

Excretion from kidney

Kidneys are the most important organ of excretory system.

There are two kidneys in our body. They resembles with Renal artery

big seeds of the bean. One of them lies on the right and Renal vein
the other on the left, high in the back part of the abdominal
cavity. Their weight varies from 130 grams to 150 grams. Kidney

Kidneys are attached with urinary bladder by tubes called

ureters. These tubes carry urine from kidney to that bladder. Ureter
That bladder is a hallow pouch that holds urine until it is

released from the body. We like to go urinal when 300ml

of urine collects in the urinary bladder. This bladder can

hold 500ml of urine. The outlet of urinary bladder is called Bladder
urethra which ends on the upper part of the penis.

Urethra

Our kidneys are like filters. They contain a million of tubes

called nephron. Their upper end remains closed and the lower end open which is attached with

collecting tube. Nephrons filter the blood which come from renal arteries of the blood. A certain

part of our blood runs slowly through our kidneys each time it circulates. The blood returns to

renal veins after filtration.

The liver stores a part of the blood-sugar and then pours it into the blood as needed between
meals. When there is more blood-sugar can be stored, the kidneys take care of the extra amount
by throwing it away in the urine.

Our kidneys help us in maintaining the right amount of water in our body. We drink more water
than our body needs. The extra water is taken out of the blood by the kidneys in the form of urine.
The more water is there in the urine, the easier it is for kidneys to throw out the waste materials
and left-over substances.

When a man is hurt and one of his kidneys is damaged and removed, he can get along quite
well with one healthy kidney. Now it is possible to replace damaged kidney with someone else’s
kidney. Successful transplantation is difficult. But doctors take new kidney from close relatives.
Sometimes machine is used to filter the blood.We must eat good food and drink plenty of clean
water to keep our kidneys healthy.

Blooming Science Book 9 283

Let’s Learn

1. In adults bone hardens by the deposition of calcium in it. Calcium is a mineral which makes
bone hard. Babies have very less calcium deposit due to it their bones are flexible not so
hard.

3. The piece of bone kept in acid for some hours softens it is because the calcium which makes
bones hard is destroyed by the acid.

4. Height of a plant does not increase, when it is cut a tip, it is because a plant has apical
meristems at apices, which are responsible for the height of a plant. By cutting the tip of a
plant, when the apical meristem is removed, its height does not increase.

5. Complex permanent tissues is also called as conducting tissue, because it consists of xylem
and phloem. Xylem conducts the flow of water and minerals from root to leaves and phloem
conducts the prepared food from leaves to other parts. Because of this reason the tissue is
called as conducting tissue.

Main Points to Remember

1. The skeleton provides supporting frame work of the body to give shape and size and protects
the internal organs.

2. The skeleton is of two types: exoskeleton (outer skeleton) and endoskeleton (inner skeleton).

3. Endoskeleton is formed inside the body which is made of bones and cartilage.

4. Bone is a hard, tough connective tissue which consists of kinds of calcium salts.

5. It is also made of living cells oestocytes, nerves and blood vessels.

6. In an adult human body, the skeleton consists of 206 bones.

7. Cartilage is a soft flexible connective tissue which is found at the end of long bones, ear
pinnae, nose etc. It acts as a shock absorber.

8. The skeletal system is a group of different types of bone and cartilages which provides
supporting framework of the body and protects the internal organs.

9. The skeleton supports the body, protects internal organs, stores calcium and phosphorus,
produces RBC and WBC and helps in the movement of body parts.

10. Bones of the skeleton is divided into two main parts the axial skeleton and the appendicular
skeleton.

11. The axial skeleton is made up of skull, vertebral column and thorax.
12. Skull is made of eight cranial bones and fourteen facial bones.
13. Vertebral column is made of thirty three pieces of vertebrae grouped as cervical (7), thoracic
(12), lumber (5), sacral (5) and coccyx (4).
14. Thorax is made of the sternum and twelve pairs of ribs.

284 Blooming Science Book 9

15. The appendicular skeleton is made up of pectoral and pelvic girdles with bones of limbs.

16. The pectoral girdle and the bones of fore arms are made of 32 pieces of bone in each side.

17. The pelvic girdle and the bones of legs are made of 31 pieces of bones in each side.

18. The femur is the longest and strongest bone in our body.

19. A joint is the site at which two or more bones meet together. On the basis of mobility they
are divided into two types. They are immovable joint and movable joint.

20. Immovable joints allow no movement of bones at joint.

21. Movable joints allow free movements in various directions such joints bear small space
called synovial cavity.

22. Synovial cavity is filled with smooth and slippery fluid called synovial fluid. It acts as
lubricantes and reduces friction between two bones.

23. There are four kinds of movable joints. They are gliding joint, hinge joint, pivot joint and
ball and socket joint.

21. Digestive system is the collective name used to describe the alimentary canal, some
accessory organs and a variety of digestive processes.

22. The digestive system deals with the reception of food and the preparation of it, for
assimilation by the body.

23. Digestive tract is also called the alimentary canal, which is about 8 to 10 metres long.

24. The teeth in the oral cavity are fastened to the sockets of alveolar processes of the jaws.

25. The tongue is a voluntary muscular structure which occupies the floor of the mouth.

26. The small intestine has the special feature and facilitated with the villi, by which the
nutrients are absorbed into the blood and lymph.

27. The large intestine does not take part in the digestion of food. All the nourishment is
absorbed and the remaining contents pass along the large intestine.

28. All living cells require a constant supply of oxygen in order to carry out their metabolism.

29. Respiration is a two-fold process whereby the interchange of gases takes place in the
tissue which is called the ‘Internal respiration’ and in the lungs ‘External respiration’
takes place.

30. The larynx or ‘voice-box’ extends from the root of the tongue and the hyoid bone to the
trachea.

31. The trachea is divided into two bronchi. Each leads into right and left lungs. The right
bronchus is a wider, shorter tube than the left bronchus and it lies in a more vertical
position.

32. Each bronchus is progressively subdivided into the smaller tubes. The finest bronchi are
called bronchioles.

33. The diaphragm is a dome-shaped structure separating the thoracic and abdominal
cavities.

Blooming Science Book 9 285

34. The supply of oxygen to the cell and tissue of the body from the environment and the
removal of carbon dioxide from tissue to environment is a continuous process.

35. The vital activities of an organism involve the decomposition of proteins, fats and
carbohydrates in different tissues, accompanied by liberation of energy and formation of
compounds called end products of metabolism.

36. The kidneys are bean-shaped paired organs, about 11 cm long, 6 cm wide and 3 cm
thick. An adult kidney weighs about 130 to 150 grams.

37. The kidneys from urine which passes through the ureters to the bladder for excretion.

38. The urethra is a muscular canal extending from the neck of the bladder to the external
urethral orifice. Its length differs between the male and the female.

39. The urinary bladder is a reservoir for urine. Its size, shape and position vary with the
amount of fluid it contains.

40. The fluid that is filtered in the glomeruli passes along the renal tubules to the renal
pelvis, from where it is collected in the bladder through the ureters.

41. The structural and functional unit of life is called cell.

42. A tissue is a collection of similar cells organized to carry out one or more particular function.

43. Plant tissue is divided into meristematic tissue, areolar and permanent tissue on the basis of
nature, position and function of cells.

44. Meristematic tissue is a group of actively dividing cells found at the tip of roots and shoot. It
is responsible for growth of plant.

45. Apical, intercalary and lateral meristems are three kinds of meristematic tissues.

46. Permanent tissue is a group of cells derived from meristematic tissue.

47. Permanent tissue is divided into simple permanent, complex permanent and special
permanent tissue.

48. Simple permanent tissue is divided into parenchyma, collenchymas and sclerenchyma.

49. Complex permanent tissue is also called as vascular tissue or conducting tissue. They help
in the transportation of prepared food material, water and minerals in the plant body. Xylem
and Phloem are complex permanent tissue.

50. Special permanent tissues perform secretary and excretory functions. It is of two types:
glandular tissue and lactiferous tissue.

PRO J ECTWORK

Make a lungs model to show the breathing process by using a cut bottle, rubber or plastic
bladder etc and show in your class.

286 Blooming Science Book 9

Exercise

1. Choose the correct answer from the given alternatives:

i. A structural and functional unit of life.

a. cell b. tissue c. organ d. all of above

ii. xylem and pholem are.

a. simple permanent tissue b. special permanent tissue

c. primary meristem tissue d. complex permanent tissue

iii. Smallest bone in our body.

a. Incus b. Nasal c. Lacrimal d. None of the above

iv. The unit of kidney is called

a. lungs b. Intestine c. renal tube d. nephrans

v. Acid produced in our stomach is

a. H2SO4 b. HCl c. H2CO3 d. HNO3

2. Answer the following questions.

a. What is tissue? Clarify the relationship between cells, tissues, organs and system.

b. How many kinds of permanent tissues are found in plants?

c. Differentiate between:

i. Xylem and phloem

ii. Meristematic and permanent tissue

d. If an apex of a plant is cut down, it does not grow tall, Why?

e. Which tissue transports water from root to other parts of the plant?

f. What type of substances are produced by glandular and lactiferous tissue?

g. Draw a neat and labeled diagram that represents the location of different types of meristems
in a plant body.

h. Name the following tissues:

i. Diffusion of gases

ii. Transport mineral and water to various parts of the plant

iii. Stores up food materials in the form of fat and prevents heat loss.

iv. Bring about an increase in the length of the internodes.

i. Name the milky fluid produced by the lactiferous tissue.

Blooming Science Book 9 287

j. Give reason:

i. Parenchyma is simple permanent tissue and phloem is the complex permanent tissue.

ii. Plants die when phloem is removed from their body.

k. What is skeleton system? How many bones are there in the body of an adult man?

m. Name the parts that make (i) Axial skeleton and (ii) Appendicualr skeleton.

n. How many vertebrae form the vertebral column in man? List the type and the number of
vertebrae present in different regions.

o. Which important part of the nervous system does the vertebral column protect? Write down
other functions of vertebral column in the human body.

p. Discuss the digestive process in human body.

q. Describe of the parts and fuctions of large intestine.

r. Write the number bones found in one side of the following human body ports.

i. Metatarsals ii. True ribs

iii. Pelvis iv. Phalanges of fore limbs

v. Patella

s. Name the following bones:

i. Cranium ii. Facial bones

iii. Shoulder girdle iv. Hind limb

t. State one function of each.

i Cranium ii. Sponbgy bone

iii. Cartilage iv. Pelvic gridle

c. Thoracic cage

u. Sketch the human skull and name the bones

v. Name the parts A, B and C in the give diagrams.

A

A

B

B

CC

w. What is atlas?
x. Enlist the major functions of skeletal system.

288 Blooming Science Book 9

3. Give reasons:
a) The bone dipped in hydrochloric acid, becomes soft.
b). Ligaments stretch when pulled by bone.
c.) Fibres are found on the tip of femur.
4. Write short notes on:
a) Small intestine
b) Large intestine
c) Alimentary canal
d) Lungs
f) Kidneys
5. Answer the following questions.
a. Explain the meaning of digestive system.
b. Name the different parts of Alimentary canal.
c. Explain the structure and functions of Stomach.
d. Write the names of Gastric juice and mention their functions.
e. What happens to air in the nasal cavity?
f. What makes you sneeze?
g. Define respiration.
h. What is the function of epiglottis?
i. How does diaphragm work?
j. What is the use of energy evolved from burning food in the cells during respiration?
k. Define inspiration and expiration.
l. How are the lungs of that person spoits who smokes a lot of cigarette?
m. Explain the meaning of urinary system.
n. List out the major organs of urinary system.
o. Sketch the organs of excretory system.
p. Discuss the functions of urinary bladder and urethra in urinary system.
q. Explain the structure and functions of nephrones.
r. Explain the process and excretion of urine.

Blooming Science Book 9 289

Chapter SENSE ORGANS

19

Learning Outcomes Estimated Periods: 2

On the completion of this unit, the students will be able to:
• describe the sense organs, their functions and structure in human being

Introduction

There are various things around us. Living organisms respond to their environment with the
help of various sense organs, nerves, brains, etc. An organism cannot exist in isolation. At all the
moment, it is subjected to many influences which come from the surroundings. The leaflets of
Mimosa pudica close up when touched. Millipede curls-up in flat spiral like a watch spring when
touched. Centipede runs away quickly when touched. Here, touch is the stimulus and closing of
leaflets, curling of body and running away from stimulus are response.

The change in the environment which induces a change in the organism is called stimulus and
reaction of the organism to the stimulus is called response.

Irritability of sensitivity is a characteristic feature of all living organisms, which involves their
ability to respond to a stimulus. In all organisms some degree of internal coordination and control
is necessary in order to ensure that the events of the stimulus and response bear some mutual
relationship associated with the maintenance of the steady-state and survival of the organism.

Animals, unlike plants, have two different but related system of coordination: the nervous system
and endocrine system. The former is fast acting, its effects are localized and it involves electrical
and chemical transmission, whereas the later is slower acting, its effects are diffused into blood
circulation. It is through that the two systems have developed in parallel in the majority of
multicellular animals.

Sense Organs

The organs, which help the living organisms to respond in changing environment, are called
sense organs. These are: ears, eyes, tongue, nose and skin.

The brief introduction of all is given here.

(a) Eye (Photoreceptor)

(b) Ears (Mechanoreceptor)

(c) Tongue (Chemoreceptor)

(d) Nose (Chemoreceptor)

(e) Skin (Thermoreceptor and mechanoreceptor)

290 Blooming Science Book 9

We can distinguish the five types of sense organs according to the stimuli they receive. They are:

S.N. Stimulus Receptor Function
1. Light Eye Seeing
2. Sound/Gravity Ear Hearing/Balancing
3. Substances (Smelling) Nose Smelling
4. Chemicals (Tastes) Tongue Tasting
5, Pain, pressure, touch and temperature Skin Feeling/Detecting

The Eye (The sense of sight)

Eye is a delicate sense organ which gives us sensation of sight. The eyes are protected in deep
sockets of skull which are orbits. Each eyeball is held in position and moved within orbit by
distinct sets of muscles attached to its outer surface.

Cornea Sclera Scan for practical experiment
Pupil Choroid
Lens Retina visit: csp.codes/c09e23
Iris
Fovea
Ciliary body
Suspensory ligament Optic disc
Vitreous body blind spot

Blood vessels
Optic nerve

Eyes are protected by various structure like

?(b) The eyelids and eyelashes prevent the eye which makes the eye red Know
(a) The dorsal part of eyeball is protected by

orbital bone of skull. DO
Conjuctivitis is a disease You

from dust, sweat and bright light. due to inflammation and

(c) The tears produced from tear glands wash away infection of conjunctiva.

the dust and germs which may enter the eye.

The eyeball consists of three coats and they are outer, middle and inner coat.

Outer Coat (Sclera)

This layer is made of a very strong and non-elastic fibrous connective tissue. It gives protection
and shape to the eyes. It is formed of two unequal parts-sclera and cornea.

At the centre, cornea consists of small opening called pupil. Cornea is covered by a thin
transparent membrane called conjunctiva. Cornea refracts light (Maximum refraction of light
takes place at cornea.)

Blooming Science Book 9 291

Middle Layer (Choroid)

Choroid consists of network of blood capillaries which provide nourishment to the eye ball. The
iris is the coloured part of eyeball having hole at the centre called pupil. Iris consists of radial and
circular muscles which help for the constriction and dilation of pupil. The size of pupil controls
the amount of light entering the eye.

The transparent, biconvex structure located just behind the pupil is lens. It performs focusing of
light rays on retina. The lens is suspended by the fibres called suspensary ligament attached to its
outer rim. These ligaments are attached to the ring of muscles fibres called ciliary muscles. The
contraction and expansion of ciliary muscles make the lens thin and thick respectively. Ciliary
muscles expand and lens becomes thick while seeing nearer objects and intract and lens becomes
thin while seeing farther objects.

The space between cornea and lens is filled with water fluid called aqueous humour. It keeps the
lens moist, protects eye from physical shock and maintains curved shape of cornea.

The space behind the lens is filled with jelly like substance called vitreous humour. It helps to
maintain the shape of eyeball, protects retina and nerves and reflection of light rays.

Inner Layer (Retina)

It is also called optical part of eyes. It contains two types of photoreceptor cells called rods

(sensitive to dim light) and cones (sensitive to bright light). Deficiency of vitamin A in rods

causes night blindness and in cones causes Owls are active at night because ?DO
colour blindness. their eyes retina have high amount
of rods. Due to less number of You
Retina contains yellow spot (fovea) and blind cone in retina, they are colorblind Know
spot. Blind spot is without rods and cones, so too. A colour blind doesnot mean
no image is formed on it while yellow spot
contains cone cells.

The nerve that carries message of image from that somone can’t see any colour.
retina to brain is called optic nerve.
In fact, colour blind can’y see red,

Care and Protection of Eyes green and blue colours only.

We can care and protect the eyes in the following ways.

a) We should not read, write and do fine works in extreme bright or dim light.

b) We should eat foods rich in vitamin A (yellow fruits, green vegetables, milk, egg, fish) to
keep our eyes healthy.

c) We should not rub eyes when dust enters. It can be removed by using a cloth or flushing
with water.

d) We should wash our eyes with clean water before going to bed and after getting up.

e) We should not remove eyelashes and eyebrows.

f) We should use medicine only after consulting the doctor in case of any problem with eyes.

292 Blooming Science Book 9

The Ear (The Sense of Hearing)

Ear is not only related to the hearing but also helps us to keep our balance. It is made up of three
major parts called external ear, middle ear and inner ear.

Semi circular
canal
Inner Ear

Ear Canal

Auditory
nerve

Cochlea

Outer ear

Pinna Middle Ear Eustachian tube

The External Ear Eardrum Malleus
Fig: Part of the ear Ear drum

It contains pinna and auditory canal. Pinna

collects sound waves. Numerous glands Incus
present in auditory canal secrete wax. Ear

gets closed with earwax due to its regular

production. We should remove earwax time
to time. Ear drum is present at the entrance Stapes

of middle ear.

The Middle Ear

It consists of three tiny bones called ear Fig: Middle ear
ossicles. They are malleus (hammer shaped),

incus (anvil shaped) and stapes (stirrup-shaped). Ear ossicles increase the force of sound waves

and conduct sound vibrations from ear drum to

internal ear.

The middle ear has an eustachian tube which
helps to keep the air pressure of inner and outer
ear in balance.

The Inner Ear Fig: Inner ear
Blooming Science Book 9 293
It consists of hearing parts (cochlea and
auditory nerve) and balancing parts (semi-
circular canals and ear-sac).

Cochlea is a bony tube which is spirally coiled
like a snail’s shell. Cochlea contains three
canals vestibular, cochlear and tympanic canal.

Vestibular and cochlear canals are filled with perilymph. Cochlear canal contains organs of corti.

Semi-circular canals are filled with endolymph. It is three in number and they are mutually
perpendicular to each other. Each canal on one side, swells to form an ampulla. Each one is
sensitive to movement in a different plane. Beneath the semi-circular canal, ear sac is present.
It is filled with fluid and it contains a tiny ball attached to a group of sensory cells with hairs for
obtaining information on the position of head.

Parts of Inner Ear and their functions

S.N. Parts Functions
1. Cochlea Changes sound vibrations into nerve impulses
2. Semicircular canals Concerned with balancing and dynamic equilibrium.

Hearing of sound is performed by cochlea and auditory nerve. The pinnae reflect sound waves to

the middle ear. The eardrum undergoes vibration due to sound waves which is then passed into

perilymph by ear ossicles and then into endolymph of cochlear canal which contains organs of

corti. Then the receptor cells transmit the stimulus to the brain through auditory nerve.

External ear

Internal ear Middle ear

Cochlear

Tympanic Nerve

Sound waves
in ear

Fig: Mechanism of hearing

Care and Protection of Ears

We can care and protect the ears in the following ways.
a. We should not insert any hard or pointed objects like needle, matchstick in the ear.
b. We should remove the earwax with the cotton buds after softening it with glycerine.
c. We should protect our ears from too loud sound. It may rupture eardrum.
d. We should immediately consult a doctor in case of pus formation, bleeding, pain and

infection in ears.
e. We should drop oil to kill and insect that has entered the ear. We should then slowly remove

it with the help of cotton bud.

The Tongue (Sense organs of taste)

Tongue contains taste receptors called taste buds. Taste Bitter
Sour
buds are stimulated only if the substance to be tasted is in
Salt
solution. We taste when the molecules in a fluid strike hairs Sour
in the taste buds and produce a reaction. Different parts of

tongue can detect the following type of tastes. Salt

Sweet and salty taste is detected by tip of tongue, sour by sides and Sweet

bitter by back part of tongue. Other kinds of tastes are formed by Fig: Tongue
combination of above main tastes.

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Tongue its regions and tastes

S.N. Taste Regions in the tongue
1. Sweet Tip of the tongue

2. Sour Sides of the tongue

3. Salty Tip of the tongue

4. Bitter Back of the tongue

Care and Protection of Tongue

We can care and protect the tongue in the following ways.
a) We should clean our tongue using tongue cleaner after brushing teeth.

b) As far as possible, we should avoid extreme hot and extreme cold foods. Such foods may
destroy our taste buds.

c) If we find infection on tongue, we should immediately consult a doctor for the treatment.

d) We should rinse our mouth with lukewarm salt water to remove yellow, black or white
coat on the tongue. We can also remove it by scrapping softly with the teeth.

The Skin (Sense organ of touch)

Skin consists of three layers. They are epidermis, dermis and subcutaneous.

Epidermis
It is the outermost protective layer. It is provided with hairs, nails, pores etc.

Dermis

It contains blood vessels, nerve endings, glands etc. Hair
Fig: Layers of skin
The nerve endings are sensitive to cold, heat, pain,

pressure, touch etc. These nerve endings are also Epidermis

called touch receptors. The touch receptors are

especially numerous in the fingertips, toes, lips etc. Dermis

Heat and cold receptors have separate nerve fibre

connections. A warm object stimulates only the heat

receptors and a cool object affects only the cold

receptors. Subcutaneous

Subcutaneous

It contains blood and fat. It helps to retain the body
heat.

Activity
Identification of receptors in the skin

1. Make a grid of 40 squares on the back of your friend’s palm. The squares have 2mm
length and 2mm breadth.

2. Poke all the parts of a square with a sharp pencil. Does it pain equally in every part?
Press harder if it pains less in some parts. Note the pains in different parts.

3. This activity can be done in other parts like arms and legs. Similar activity can be done
to identify the senses of hot, cold, touch etc.

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Care and Protection of Skin

We can care and protect the skin in the following Hair
ways. Fig: Layers of skin

a. We should wear clean clothes. Epidermis

b. We should not wear the clothes that are too

tight or cannot absorb sweat well. Dermis

c. We should bath daily if possible. It opens the
pores and body becomes active.

d. We should not expose our skin to direct

sunlight for a long time. Subcutaneous

e. We should go for immediate treatment if

wound, boils or scabies appear.

The Nose (Sense organ of smell)

The inner lining of nose surface is made up of epithelium. The roof of nasal cavity is concerned
with the sense of smell and rest part of breathing. For getting smell of something, it has to be the
in the form of solution. When there is something to be smelled, the impulses from the receptors
for smell are carried by olfactory nerve to the brain. The interpretation of smell is closely related
to the sense of taste.

When a person gets cold, the epithelium is swollen and the particles of odorous substance cannot
reach the olfactory cells and therefore he/she does not get sense of smell.

Care and Protection of Nose Olfactory nerve Frontal Olfactory Olfactory
endings and nerves sinus bulb tract
We can care and protect our nose in the following
ways.

a) Hairs in nostrils should not be removed.
They prevent dust and micro-organisms from
reaching the lungs.

b) We should use mask to protect the nose from
dust and smoke.

c) We should not scratch the nose inserting Inferior concha
finger or any other objects. Middle concha
Superior concha
d) In case of bleeding, we should rest keeping
the nose up. Fig: structure of nose

e) We should go for the quick treatment in case of nose infection or cough and cold.

Let’s Learn

1. A person having hole in ear drum does not hear properly because the ear drum receives
less sound which cannot pass into the brain through the cochlea.

2. Colour is not seen distinctly in moon light because rods are sensitive to dim light so these
help in twilight vision during night. Rods contain a pigment rhodopsin which is readily
bleached by brought light into a protein which depolarizes the rod cell. The rhodopsin is

296 Blooming Science Book 9

rapidly regenerated in dim light so colour is not seen distinctly in moon light.

3. A person cannot balance after spinning sometime because the endolymph of the ear goes
to one side and strong impulses from semicircular canals pass to brain. Again, when the
spinning is stopped endolymph rushes back to normal. It means cerebellum cannot work
properly. This creates giddiness and one cannot overcome the feeling of falling down.

4. A person does not have common sense of smell during suffering from cold because the
inner lining of the nose called epithelium is swollen. Moreover, during cold, the particles
of odorous substance cannot reach the olfactory cells and therefore a person does not get
sense of smell. The nose is infected by rhino virus.

5. We couldn’t distinguish or identify smell if it is taken repeatedly because the sense of
smell is fatigued very fast. If we smell repeatedly after sometime we become usual to the
smell and have no longer its smell.

6. Chocolate is given while travelling by aero plane because it helps to balance the air
pressure on both sides of the eardrum through Eustachian tube and there is no possibility
of disturbance on the eardrum.

Main Points to Remember

1. Those organs which help the living organism to be aware of changing environment are
called sense organs.

2. The five sense organs of body are eye, ear, nose, tongue and skin.
3. Eye is the very delicate and important organ of vision. It has three coats, sclera, chloroid

and retina.
4. Two types of photoreceptor cells found in retina are rod and cone cells.
5. The rod cells contain visual pigments. They are sensitive to bright light.
6. The cone cells are sensitive to dim light.
7. The nerve that carries message of image from retina to brain is called optic nerve.
8. A real, inverted and diminished image is formed on the retina.
9. Ear is an organ of hearing and balancing. It can be divided into external, middle and inner

ear.
10. The middle ear consists of an air filled cavity called tympanic cavity.
11. Three ear ossicles-malleus, incus and stapes conduct sound waves from ear drum to the

internal ear.
12. Cochlea of the internal ear is concerned with hearing while semicircular canal is concerned

with balancing.

13. The taste buds in the tongue are supplied with nerves that detect different tastes of the
food.

14. Skin is the outermost covering of the body.

15. The receptors in the skin are sensitive to heat, cold, pain, touch and so on.

16. Nose is a sense organ of smell. The nerve fibres of the olfactory nerve are present in the
epithelium of the nasal cavity.

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PRO J ECTWORK

Find the part of tongue sensitive for various tastes

1. Take about 10 ml of salt solution, about 5ml lemon juice and about 10 ml sugar
solution in three different plates with four tooth picks in each.

2. Call four friends (two boys and two girls) of your class and put a droplet of the liquid
at the four regions of the tongue of your friend. Use only one solution from a person.

3. Note their feeling of taste to understand about the region of different taste buds.

Exercise

1. Choose the correct answer from the given alternatives.

i. A thkin and muscular muscle, present in eye

a. Iris b. Ciliary body c. Choroid d. all of above

ii. The image formed on retina is .
a. Real b. Inverted c. Diminished d. all of above

iii. The semi circular canal is found in

a. middle ear b. Inner ear c. Outer eye d. all of the above

iv. The taste of sour is felt in ....................... of tongue.

a. tip b. sides c. back d. none of the above
v. What is the function of pupil?

a. control eye pressure b. regulates the passage of light in eye

c. work as screen d. none of above

2. Answer the following questions.

a. What are sense organs? Why are they important?
b. In which area of the tongue detect sweet, salty, bitter and sour tastes?
c. Draw a diagram of the human eye and label cilliary muscles, lens, iris and retina.
d. What type of vision are rods and cones associated with?
e. Draw a well-labelled diagram of human ear.
f. Why do foods seem to have fewer flavour when you have a cold in the nose?
g. What will happen if ear ossicles are removed from the middle ear?

3. Give reason.

a) After rotation for some time, a person loses his balance.

b) Inability to see in a dark room immediately after coming from lighted room.

c) A pupil of eye gets enlarged when a person moves towards dark.

d) Sweet taste can be felt faster than bitter taste.

e) If the strong odour is smelt continuously for some time, the sensation of smell of
that substance weakens.

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4. In which organ are the following structure situated?

a) Rod cells b) Ear ossicles

c) Cochlea d) Blind spot e) Semicircular canals

5. Write the function of the following.

a) Semicircular canal b) Cochlea c) Cillary muscles

d) Cornea e) Eardrum f) Olfactory nerve

g) Eustachian tube h) Optic nerve

6. Distinguish between:

a) Rods and cones b) Night blindness and colour blindness

c) Aqueous humour and vitreous humour

7. What happens if

a) Ciliary muscles are not functioning properly. b) Ear drum is ruptured.

8. Name three bones found in middle ear.

9. Write down the following parts of ear in the order from outer ear to the middle ear and
mention which part separates these two parts of ear.

Malleus, auditory canal, pinna, incus, eardrum

10. Study the diagram shown below and answer the following questions.

a) A and B are two special muscles of eye. Name them.

b) Write one function of each of ‘A’ and ‘B’ A
11. How should we take care and protect our sense organs? B
12. Salty taste can be felt faster than bitter taste. Give reasons.

13. Study the given diagram to answer the following questions.

a. What sense the given organ related with?

b. Out of A, B, C and D which one is related with sour? A

c. Out of A, B, C and D, sense of which is stimulated by more BB

temperature?

d. If you are eating sweets, which part of the above organ will help you

to get sense of sweet? DC

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Chapter EVOLUTION

20

Learning Outcomes Estimated Periods: 4
On the completion of this unit, the students will be able to:
• explain history and theories of evolution.
• define evidences of organic evolution.

If we look around us, we see many kinds of plants and animals. They differ from one another
in different aspects. When one studies about plants and animals, the question arises in his mind
about the origin and the evolution of these organisms on the earth. How did they originate? When
did they originate? How do they evolve and give rise to diversified organisms? It is very difficult
to answer how life originated. About the origin of life, several hypotheses have been put forth.
Some of them with their short explanation are given below.

1. Theory of special creation

2. Theory of spontaneous generation

3. Modern concept of origin of life

1. Theory of Special Creation

According to this theory, on the earth life was created by supernatural power, the God. He
created all plants and animals, which appeared on the earth in the form they exist today. This
theory has no scientific evidence therefore, it is not widely accepted.

2. Theory of Organic Evolution

According to this theory, the present physical forms of plants and animals that we see on
the surface of the earth are not the same as those of the original plants and animals. The present
physical form of plants and animals are derived from relatively simpler forms. However, there
complex highly developed forms are the results of extremely slow and gradual step by step
change over millions of years. The evolution is a continuous process, and, it is suggested by the
process goes on forever.

The highly organized and complex forms of life of today are formed by the modification
of the already existing unorganized forms of past evolution called organic evolution, it is the
process of slow and gradual change to form complex organism from simpler ones over a period
of millions of years. Organic evolution can also be defined as descent with modification.

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