Oasis School Science and Technology 8 New

Oasis School Science and Technology - 8 47 8. Nuclear membrane : A double-membraned porous structure which separates the nucleus from the cytoplasm is called a nuclear membrane. 9. Nucleoplasm : A transparent semi-fluid substance containing nucleolus, chromatin network and various enzymes is called nucleoplasm. 10. Endoplasmic reticulum : The system of flattened membrane-bound tubules enclosing a fluid-filled lumen is called the endoplasmic reticulum. 11. Mitochondria : The spherical or rod-shaped cell organelles that can do cellular respiration are called mitochondria. 12. Ribosomes : Ribosomes are minute, spherical granules which are the site of protein synthesis. 13. Endoplasmic Reticulums: Endoplasmic Reticulums are the branching tubules and flattened sacs that extend throughout the cytoplasm. 14. Lysosomes : The sac-like spherical structures present in the cytoplasm that contain digestive enzymes are called the lysosomes. 15. Vacuole : The non-living, fluid-filled spaces present in the cytoplasm is called a vacuole. 16. Plastids : The disc-shaped cell organelles found only in plant cells are called plastids. 17. Chloroplasts : The green plastids are called chloroplasts. 18. Chromoplasts : The colourful plastids are called chromoplasts. 19. Leucoplasts : The colourless plastids are called leucoplasts. 20. Unicellular animals : The animals having a single cell in their bodies are called unicellular animals. 21. Multicellular animals : The animals having many cells in their bodies are called multicellular animals. 22. Tissue : A group of cells is called tissue. 23. Organ : A group of tissues that performs a particular function is called an organ. Introduction All living organisms are made up of microscopic units called cells. These cells are called building blocks of life. A cell is defined as the basic, structural and functional unit of life capable of independent existence. A cell is made up of life giving substance called protoplasm. Cell was discovered by Robert Hooke in 1665 AD. He observed a thin slice of cork under his self-built microscope and found that the cork piece had numerous compartments connected together in a honeycomb-like structure. He named these compartments as cells (L., cella- compartments). Objective lenses Stage clip Mirror Stand Fine adjustment knob Coarse adjustment knob Eye piece Stage Fig: compound microscope

48 Oasis School Science and Technology - 8 All living organisms are composed of cells or cell products. All new cells arise as a result of divisions of pre-existing cells. All cells are basically alike in chemical composition and metabolic processes. The function of an organism as a whole is the outcome of combined activities and interactions of the constituent cells. Cells are the structural and functional units of all living beings. Therefore, cell is called the fundamental, structural and functional unit of life. Prokaryotic Cells and Eukaryotic Cells On the basis of nuclear organization, cells are of two types: Prokaryotic cell and Eukaryotic cell. The cell that lacks a well organized nucleus is called a prokaryotic cell. It lacks several membrane bound cell organelles like mitochondria, lysosome, endoplasmic reticulum, etc. Such type of cell is found in bacteria, blue-green algae, etc. The cell having a well organized nucleus is called a eukaryotic cell. It contains nuclear membrane, nucleolus and membrane bound cell organelles. Such type of cell is found in most of the plants and animals. Reasonable Facts Bacteria is called prokaryotic. Bacteria is called prokaryotic because it does not have proper nucleus and lacks other membrane bound cell organelles. Activity 1 Observe onion slide through compound microscope. Cell Shape, Size and Number Generally, plant cells are rectangular and animal cells are oval. However, they show a great variation in their shapes. Cells may be oval, polygonal, cubical, elongated, etc. Cells show a great variation in their sizes. Most of the cells are tiny and microscopic whereas a few cells are macroscopic. The smallest known cell is mycoplasma. Its size is 0.5 to 5 mm (micrometer). The largest cell is the egg of ostrich. Its size is 15 cm long and 13 cm wide. Microscope is used to observe the internal details of a cell. Many organisms are made of a single cell. They are called unicellular organisms, e.g. amoeba, Plasmodium, bacteria, etc. Most of the plants and animals are made of multiple cells. They are called multicellular organisms. Detailed Structure of a Typical Cell Cellsofdifferentorganismsdifferintheir structure.Cells even within a body of multicellular organisms differ in their shape, size and function. In spite of these differences, every cell shows the same basic structure as discussed below. Fact File Mostly organisms of Monera kingdom have prokaryotic cells.

Oasis School Science and Technology - 8 49 Cell wall It is the outermost rigid and protective covering layer of plant cells. It is absent in animal cells. It is made of non-living secretion called cellulose. It is metabolically active and is capable of growth. It is freely permeable in nature. Functions i. Cell wall provides a definite shape and rigidity to the plant cell. ii. It protects plasma membrane and internal parts of the cell. Plasma membrane Every cell is surrounded by a living, elastic and delicate membrane called plasma membrane. In plant cells, it is found inner to the cell wall. It is made up of lipid and protein molecules. It contains numerous small pores in it. It is a selectively permeable or semi-permeable membrane as it allows only selected substances to enter or leave the cell. Functions i. Plasma membrane provides an outer boundary to a cell and protects it from external injury. ii. It helps in transport of materials in and out of the cell. Cytoplasm The space between cell membrane and nuclear membrane is filled with a translucent liquid called cytoplasm or protoplasm. It consists of carbohydrates, proteins, lipids, nucleic acids, sodium and potassium salts, water and enzymes. Various cell organelles and inclusions remain floating in the cytoplasm. Functions i. It helps in intracellular distribution of molecules, enzymes and nutrients within the cell. ii. It contains many cell organelles and provides space for various metabolic activities. iii. It helps in the exchange of materials between many cell organelles. Cell wall Cell membrane Golgi apparatus Chloroplast Vacuole membrane Raphide crystal Druse crystal Mitochondria Cytoplasm Large central vacuole Rough (ER) Nucleus Nucleolus Endoplasmic reticulum (ER) Ribosome Fig: typical structure of a plant cell Fig: typical structure of an animal cell Fact File Cytoplasm distributes nutrients and enzymes within the cell organelles.

50 Oasis School Science and Technology - 8 Reasonable Facts Cytoplasm is called living fluid. Cytoplasm is called living fluid because it is responsible for various life processes. Activity 2 Observe a plant cell and an animal cell through a compound microscope. Nucleus Nucleus is a round or spherical cell organelle present almost at the centre of a cell. It consists of nuclear membrane, nucleoplasm, nucleolus and chromatin network. The nuclear membrane is double membraned porous structure which separates nucleus from the cytoplasm. It is porous. It protects the nucleus. It controls entry and exit of materials in the nucleus. i. Nucleoplasm Nucleoplasm is a transparent semi-fluid substance containing nucleolus, chromatin network and various enzymes. It is made of water, protein, minerals, nucleic acid and enzymes. It helps in DNA replication, RNA transcription and balance the amount of water. ii. Chromatin network The chromatin network is a long thread like structure that is found in nucleoplasm. It contains hereditary information because it is made of genes, DNA and protein. They become short and thick during cell division and are called chromosomes. There are 23 pairs of chromosomes in a human cell. The split chromosome is called chromatid. iii. Nucleolus Nucleolus is a dense and round structure made of RNA and protein. It helps in the formation of spindle fibre during cell division. It disappears during cell division and reappears when the new nucleus are formed at the end of cell division. Functions of nucleus i. Nucleus controls various metabolic activities of the cell. So, it is also called the director of the cell. Fig: Structure of nucleus Chromatin network Nuclear membrane Necleoplasm Nucleolus Nuclear pore

Oasis School Science and Technology - 8 51 ii. It helps in cell division and hence in reproduction. iii. The DNA present in the nucleus helps to transfer the hereditary information from the parents to the offspring. Endoplasmic reticulum Endoplasmic reticulum is a system of flattened membrane bound tubules enclosing a fluid filled lumen. It almost fills up the intracellular cavity. On one end endoplasmic reticulum is connected to the nuclear membrane and on another end it is connected to the plasma membrane. It forms the endoskeleton of the cell. Endoplasmic reticulum is of two types: smooth endoplasmic reticulum and rough endoplasmic reticulum. Ribosomes are attached to the surface of rough endoplasmic reticulum whereas they are absent on the surface of smooth endoplasmic reticulum. Functions i. It forms the supporting framework of the cell and provides mechanical support to the cytoplasm. ii. It helps in intracellular transport. iii. It provides a large surface area to the cytoplasm for various metabolic activities. Activity 3 Make a 3 D model of animal cell and label any 3 parts. Mitochondria Mitochondria are spherical, rod-shaped or thread-like cell organelles present in the cytoplasm. Each mitochondrion is enclosed by an outer membrane and an inner membrane. Mitochondria are sites of energy production and storage of energy during cellular respiration. So, they are also called power plant of the cell. Functions i. Mitochondria use molecular oxygen to oxidize the carbohydrates and fats to release energy for the cell. ii. They synthesize many amino acids. Fig: Rough endoplasmic reticulum Membranes Ribosomes Fact File Smooth ER helps in lipid formation. Fig: Mitochondrion Matrix Cristae Inner Outer membrane membrane

52 Oasis School Science and Technology - 8 Ribosomes Ribosomes are minute, spherical granules attached to the tubes of endoplasmic reticulum. But they may occur free in the cytoplasm. Ribosomes are composed of RNA and protein. They are called protein factory. Function Ribosomes are responsible for protein synthesis. They help in gene expression. Golgi complex Golgi complex consists of a set of membrane-bound fluidfilled vesicles, tubules and vacuoles. It is generally found near the nucleus in the cytoplasm. The golgi apparatus arises from the membrane of the smooth endoplasmic reticulum and originates from the rough endoplasmic reticulum. It was discovered by Camilo Golgi in 1898. Functions i. It acts as a way station for storage, processing and packaging of various cellular secretions like enzymes, proteins, etc. ii. It produces vacuoles or secretary vesicles that contain cellular secretions. iii. It is responsible for the synthesis of cell wall, cell membrane and lysosomes. Lysosomes Lysosomes are sac-like spherical structures present in the cytoplasm. Each lysosome is surrounded by a single membrane. Lysosomes contain powerful enzymes which can digest all types of substances. They may even digest the entire damaged cell or dead cell. So, lysosomes are also called suicidal bags of the cell. Functions i. Lysosomes help in intra-cellular digestion. ii. They provide energy during starvation by controlled breakdown of stored food. iii. It supplies nutrition during germination of seed. Vacuoles Vacuoles are non-living, fluid-filled spaces present in the cytoplasm. They are enclosed by a membrane called tonoplast. In plant cells, vacuoles are larger in size and less in number whereas they are smaller but more in animal cells. Vacuoles are filled with a fluid which contains water, minerals, carbohydrate, organic acids, etc. In animal cells, vacuoles are temporary. Functions i. Vacuoles help the cell to remain turgid. ii. They store water, minerals and waste products. iii. Vacuoles help in growth of the cell. Fig: Golgi complex Vacuole Cisternae Secretory vesicle

Oasis School Science and Technology - 8 53 Plastids Plastids are disc-shaped cell organelles only in plant cells. Plastids are of three types: chloroplast, chromoplast and leucoplast. Chloroplasts are green plastids. They appear green due to the presence of photosynthetic pigment called chlorophyll. Chloroplasts are involved in the synthesis of food. So they are also called 'kitchens of the cells'. Chloroplasts are found in leaves, young stem, sepal and young fruits. Chromoplasts are colourful plastids. They are found in petals of flowers and pericarp of fruits. They do not contain chlorophyll. They contain red, yellow and orange pigments. Leucoplasts are colourless plastids. They are found in the cells of underground storage organs. If exposed to light for a considerable period, leucoplast may change into chloroplast. Chloroplasts help to form fatty acid and amino acid. They also store DNA and genetic characteristics. Chromoplasts give colours to the fruits which helps in dispersal of seeds. Functions i. Chloroplasts trap solar energy and utilize it for photosynthesis.Chloroplasts help to form fatty acid and amino acid. They also store DNA and genetic characteristics. ii. Chromoplasts impart various colours to flowers and attract insects for pollination. Chromoplasts also give colours to the fruits which helps in dispersal of seeds. iii. Leucoplasts store food in the form of carbohydrate, protein and fat. Reasonable Facts Plants are autotrophic. Plants are autotrophic because of the chloroplast. Chloroplast contains chlorophyll which can capture ultraviolet rays of the solar radiation for photosynthesis. Activity 4 Learn more about functions of chloroplast through internet. Centrosome Centrosome is a small naked protoplasmic structure. It is located in the cytoplasm near the nucleus of animal cells. It contains astral rays and two small granules called centrioles. Functions i. Centrosome initiates and regulates cell division in animal cells. ii. It acts as a basal body to give rise to cilia and flagella. Fig: Plastid Fact File Leucoplast helps in conversion of amino acid and fatty acid.

54 Oasis School Science and Technology - 8 Differences between Plant cell and Animal cell S.N. Plant cell S.N. Animal cell 1. Plant cell is usually larger in size and rectangular in shape. 2. Cell wall is present. 3. Centrosome is absent. 4. Plastids are present. 5. Vacuoles are larger and well developed. 6. Golgi bodies are diffused. 7. Food is stored in the form of starch or oil. 1. Animal cell is comparatively smaller in size and oval in shape. 2. Cell wall is absent. 3. Centrosome is present. 4. Plastids are absent. 5. Vacuoles are smaller and scattered. 6. Golgi bodies are well developed. 7. Food is stored in the form of glycogen. Activity 5 Microscopic examination of onion peels to study plant cells · Take an onion bulb and remove the outer dry scales. · Cut the bulb into small pieces vertically and remove the fleshy scale. · Bend the outer convex surface of the fleshy scale and pull the broken thin transparent layer with forceps. · Place the peel (i.e. thin layer) in a watch glass containing water. · Prepare a temporary slide of the peel and observe it under the compound microscope. · Draw a neat labelled figure and comment on it. cytoplasm nucleus vacuole cell wall piece of epidermal layer Onion scale Onion cells under L.P. Single cell under H.P. Fig: cell Unicellular and Multicellular Animals The animals having a single cell in their bodies are called unicellular animals, for example, amoeba, paramecium, euglena, etc. The animals having many cells in their bodies are called multicellular animals, for example, hydra, butterfly, fish, bird, human being, etc. In unicellular animals, all the activities like respiration, excretion, reproduction, sensation,

Oasis School Science and Technology - 8 55 etc. occur in the single cell. But multicellular animals have tissues, organs and systems for performing specific functions. Interrelationship among Cells, Tissues and Organs Cell is the basic, structural and functional unit of life. The body of all living organisms is made up of cells. A unicellular organism consists of only one cell whereas multicellular organisms contain many cells. The single cell of unicellular organisms can perform various activities like respiration, excretion, reproduction, digestion, etc. But in case of multicellular organisms, there are separate groups of cells responsible for different functions. Such group of cells is called tissue. The cells of a tissue show similar pattern of growth and development. In the developed organisms, there are many functions being carried out by various tissues in the group. Such group of tissues that performs a particular function is called an organ. In the body of an organism, a set of organs acts together to perform a certain function, e.g. digestive system, circulatory system, etc. Various systems act together and form a complete organism. Thus, there exists a close relationship among cells, tissues, organs and systems. Cell + Cell → Tissue Tissue + Tissue → Organ Organ + Organ → System Example: Liver is the main organ of human body which performs many functions in our body. The major functions of liver are as follows: i. The bile juice secreted by liver helps to digest fat. ii. It produces heat in the body. iii. It destroys red blood cells. iv. It regulates the amount of sugar in blood. v. It detoxicates drugs. vi. It synthesizes vitamins. vii. It forms urea and uric acid that are excreted in urine. Activity 6 Make a 3D modal of liver and explain its functions to the class. Various systems, organs and tissues of human body and their functions are given in the table below: S.N. Systems Organs Tissues Functions 1. Digestive system Mouth, stomach, liver, pancreas, intestine Columnar epithelium, involuntary muscle Digestion and absorption 2. Respiratory system Nose, wind pipe, lungs Pavement and cubical epithelium To exchange oxygen and carbon dioxide Fact File Liver converts glucose into glycogen and stores it.

56 Oasis School Science and Technology - 8 3 Circulatory system Heart, blood, blood vessels Pavement epithelium, cardiac muscle, smooth muscle, connective tissue To supply food and oxygen, fight against infection 4. Excretory system Kidney, liver, ureter, urinary bladder Pavement and cubical epithelium To excrete waste materials 5. Muscular system Various types of muscles Skeletal, smooth and cardiac muscle To help in movement of body parts, to give shape 6. Skeletal system Bones and cartilage Connective tissue To give internal framework, to help in locomotion 7. Reproductive system Testes, ovaries vagina, penis, etc. Cubical and columnar epithelium Sexual reproduction 8. Nervous system Brain, spinal cord and nerves Nervous tissue Sensory 9. Endocrine system Endocrine glands Glandular epithelium To bring about harmonious development of body Reasonable Facts There is close relationship among cells, tissues and organs. All life forms are composed of cells. Cell is the basic, structural and functional unit of life. Tissue is a collection of similar cells having similar structure and adapted to perform a set of function, i.e. similar pattern of growth and development. An organ is the group of tissue that performs a particular function. This shows that tissue is the collection of cells and organ is the collection of tissues which are closely related to each other. So, there is close relationship among cells, tissues and organs. Activity 7 Take a tip of a growing plant. Cut a thin slice of the tip and prepare a slide. Observe the slide under the compound microscope and draw a neat and labelled figure.

Oasis School Science and Technology - 8 57 Reasonable Thinking Skill Reasonable Thinking Skill R T S 1. Mitochondria is called the powerhouse of the cell. How does it produce energy? Mitochondria are called the powerhouse of the cell because they can produce energy for the cell. Mitochondria absorb glucose and oxygen from the blood. The inner layer of mitochondria contains cristae. At cristae, the glucose and oxygen undergo a chemical change and produce adenosine triphosphate. ATP is used by cells as fuel for metabolic activities. 2. Compare between the cell wall and cell membrane. The differences between the cell wall and cell membrane are: SN Cell wall SN Cell membrane 1 The cell wall is made of cellulose. 1 The cell membrane is made of lipids and protein. 2 It is present in Monera, Plantae and fungi. 2 It is present almost all organisms. 3 Cell wall is permeable. 3 Cell membrane is semi-permeable. 3. Cells are called a functional units of life. All living things are made up of cells. Living things perform various activities to stay alive. Some of them are breathing, digestion, respiration, locomotion, formation of enzymes, cell division etc. All of these activities are carried out by cells. Therefore, cells are called the functional unit of life. 4. Do all organisms in the world have the same type of cell or do they differ? Are all cells in one organism identical? If not, why do they vary in shape, size and colour? The cells of each species of the organism are unique. Each of them has a different number of chromosomes and genes. All cells in a single organism are also not identical. They vary in shape, size and colour because they are found at different location of the body and has different types of work to do. 5. What kind of relationship among cells, tissues and organs, keeps us alive? Cells are the basic unit of life. Each of them has particular work to do. For example, a red blood cell transports oxygen, a neuron processes information etc. Multiple cells of similar origin, and similar function makes tissues. Tissues combine to form organs. Organs also have particular work to do. For example, the lungs help in the exchange of gases, the heart pumps blood and the pancreas produces enzymes and hormones. Multiple organs work together for performing particular life processes. They are called systems. For example, for respiration, the nose takes air in, the windpipe brings air to the lungs and the alveoli at the lungs exchange oxygen and carbon dioxide. The blood takes oxygen from the lungs and then gives it to cells. The cells use that oxygen to release energy by oxidation of food. Such relationships among cells, tissues and organs keep us alive.

58 Oasis School Science and Technology - 8 6. Do you know that drinking alcohol kills human? Which organ is mostly damaged by alcohol? What metabolic activities will be disturbed if alcohol damages the liver? Yes! I know that drinking alcohol kills human. The liver is mostly damaged by alcohol. If the liver is damaged, the following activities will be disturbed: i. Bile juice production will be irregular. ii. Liver cannot produce the sufficient vitamin. iii. There will be an imbalance in sugar concentration in the blood. iv. Liver cannot effectively remove poison from the body. 7. Which cell organelle helps in the cell division of animal cells? Are they present in a plant cell? What other organelles are unique to animal cells? Centrosome helps in the cell division of the animal cell. No! The centrosome is not present in the plant cell. Some cell organelles that are unique to animal cells only are: i. Lysosome ii. Cilia and flagella 8. Describe the structure of the nucleus with a diagram. Why is it called the control centre of the cell? The nucleus is a small spherical cell organelle that floats in the cytoplasm. It is surrounded by double-membraned nucleoplasm. It is filled with nucleoplasm. Nucleoplasm is a liquid that contains chromatin fibres and nucleolus. The outer layer of the nuclear membrane works with the endoplasmic reticulum. The nucleus is called the control centre of the cell because it controls all metabolic activities of the cell. Exercises 1. Choose the best answer from the given alternatives. a. What makes the cell wall of a plant? i. lipid ii. keratin iii. chitin iv. cellulose b. What gives green colour to the plastid? i. chloroplast ii. chloroform iii. chlorofluorocarbons iv. chlorophyll c. What is the process by which energy is released in the cell? i. respiration ii. breathing iv. digestion v. nutrients

Oasis School Science and Technology - 8 59 d. What is the function of lysosome? i. maintain turgidity of cell ii. protein synthesis for cell iii. help cell for suicide iv. digestion and removal of waste e. Which cell organelle is responsible for protein synthesis? i. golgi body ii. ribosome iii. endoplasmic reticulum iv. centrosome 2. Define the following terms with required examples. a. Cell b. Prokaryotic cell c. Eukaryotic cell d. Cell wall e. Cell membrane f. Cytoplasm g. Nucleus h. Endoplasmic reticulum i. Mitochondria j. Lysosome k. Vacuole m. Plastid n. Chromoplast o. Leucoplast p. Chloroplast q. Unicellular organism r. Multicellular organism s. Tissue t. Organ u. System 3. Very short questions a. What pushes the nucleus of a plant cell to the extreme corner of the cell? b. What are the constituents of cytoplasm? c. Which cell organelle helps in intracellular digestion? d. If ribosomes produce protein, what cell organelle packages the protein? e. If the respiratory system helps in the exchange of gases, which system helps in the harmonious development of the body? f. Write the name of energy produced from mitochondria. g. Name the scientist who discovered the cell. h. Who coined the term cell? i. Which organ controls the overall activity of the cell? j. Which cell organelle initiates cell division in an animal cell? 4. Give reasons a. Cells are called the structural and functional unit of life. b. Cell membrane is called a semi-permeable membrane. c. Mitochondria is called the powerhouse of the cell. d. Lysosome is called the suicidal bag of the cell. e. Leaves are green. f. Leaf is called the kitchen of the plant. g. Cells differ in shape and size.

60 Oasis School Science and Technology - 8 5. Differentiate between a. Unicellular and multicellular organisms b. Eukaryotic cells and prokaryotic cells c. Cell wall and cell membrane d. Mitochondria and nucleus e. Lysosome and vacuole f. Chloroplast and chromoplast 6. Short question answers a. Draw a labelled diagram of the animal cell. b. Enlist the cell organelles that are present in either plant cells or animal cells only. c. What are the roles of cytoplasm in the cell? d. What are the functions of the endoplasmic reticulum? e. Write down the function of the Golgi body. f. Describe the interrelationship between cells, tissues and organs. 7. Long question answers a. What is known as the powerhouse of the cell? Draw its diagram. Why does that organ have multiple cristae? b. Where are ribosomes found? What do they do for the cell? c. How many types of plastids are there in a plant cell? Enlist them. What are their functions? d. Discuss the importance of the cell for living things. e. Describe the structure of the nucleus with a labelled figure. f. Describe the structure of a plant cell with a neat and clean diagram. g. Name the parts A, B, C, D and E in the given diagrams. Also identify the type of cell and also tell the reason. A B C D E A B C D E

Oasis School Science and Technology - 8 61 UNIT 3.2 CLASSIFICATION OF LIVING BEINGS Estimated teaching periods Theory 5 Practical 1  Introduction to two kingdom system of classification and five kingdom system of classification  Introduction to microorganisms  Positive effects of microbes such as decomposition of organic materials, uses of yeast, curd formation, production of antibiotics, antibodies and antivirals.  Negative effects of microbes such as food spoilage, wound infection and infectious diseases  Methods to prevent diseases and infection caused by germs  Methods to prevent food spoilage. The Sequence of Curriculum Issued by CDC Robert Harding Whittaker is an American Plant ecologist known for introducing five kingdoms taxonomic classification. He was born on 27th December 1920 and died on 20th October 1980. His work five kingdom system of classification was better to explain the evolutionary relations among the organisms than the two kingdom systems of classifications. He has contributed to the classification of Biome. He obtained his B.A. from Washburn Municipal University and PhD in biology at the University of Illinois. About the Scientist Robert Harding Whittaker Key terms and terminologies 1. Classification : The method of arranging living organisms into various groups based on similarities and differences is called classification. 2. Taxonomy : The branch of biological science that deals with nomenclature and classification is called taxonomy. 3. Nomenclature : The way of providing a scientific name for every living organism is called nomenclature. 4. Binomial system of Nomenclature: The scientific method of assigning two names, i.e. generic name and specific name to an organism is called a binomial system of nomenclature. 5. Genus : A group of closely related species resembling each other is called a genus. 6. Species : A group of similar organisms that can breed together and produce fertile offspring is called species.

62 Oasis School Science and Technology - 8 7. Monera : The kingdom that includes unicellular prokaryotic microscopic organisms is called Monera. 8. Protista : The kingdom that includes eukaryotic unicellular organisms is called Protista. 9. Fungi : The kingdom that includes unicellular and multicellular nongreen thallus organisms is called fungi. 10. Microscopic organism : The organisms which cannot be seen with our naked eyes are called microscopic organisms 11. Bacteria : The smallest and most widespread single-celled prokaryotic organisms are bacteria. 12. Viruses : The smallest and possibly the most primitive, acellular, nonprotoplasmic bodies are called viruses. 13. Dehydration : The process of removing water from food is known as dehydration. Introduction The earth is inhabited by millions of plants and animals. It is estimated that there are about 10 million species of organisms on the earth, but only one third of them have been identified and described to date. The organisms are not only enormous in number but also present in a considerable diversity of body structure, habits and modes of life. Visualizing such a vast number of organisms it would be almost impossible to study each and every plant and animal separately at the individual level. Therefore, different kinds of organisms are arranged in an orderly and systematic manner into various groups under the species on the basis of their similarities and differences. Then, species are arranged into higher and higher categories like genus, family, order, class, phylum, etc. This process is called classification. Thus, classification can be defined as the method of arranging living organisms into various groups on the basis of similarities and differences. In classification, the similarities and differences between organisms are identified and then the organisms having similar characters are placed in the same group. Biological classification attempts to group living organisms on the basis of how closely related they are. Importance of Classification i. It helps us in identification and grouping of various organisms. It makes the study of living organisms easy and systematic. ii. It helps us understand the relationship among different groups of organisms. iii. Classification projects a picture of all life forms at a glance. iv. It gives us the idea about the evolution of organisms. Taxonomy Taxonomy or Systematic Biology is defined as the branch of biological science that deals with the nomenclature and classification. Taxonomy is concerned with naming and systematically arranging different species of organisms into closely related groups on the basis of their relationship. A Swedish scientist Carolus Von Linnaeus (1707-1778 AD) is considered as the father of taxonomy because he developed the Binomial System of

Oasis School Science and Technology - 8 63 Nomenclature and system of classification. In 1735 AD, he published a book, Systema Nature, in which he mentioned the binomial names and the method of classification. The tenth edition of this book published in 1758 AD is still the basis of modern classification. Nomenclature Nomenclature is the way of providing a scientific name for every living organism. Common vernacular names for the same organism vary from place to place. For example, the bird which is known as 'Bhangero' in Nepal is known by different names in different countries. It is called 'Gauraiya' in India, House sparrow in England, Suzune in Japan, Pardal in Spain, Musch in Holland and so on. These names may not be understood elsewhere. Thus, a need was felt to assign a particular organism with an internationally acceptable name. Therefore, a simplified system of naming organisms known as 'Binomial System of Nomenclature' was proposed by Carolus Linnaeus. Binomial System of Nomenclature In Biology, every living being is given two proper names. The first name is the genus to which the organism belongs whereas the second name is the species to which it belongs. For example, the scientific name of frog in binomial system is Rana tigrina in which Rana is the genus, i.e. generic name and tigrina is the species, i.e. specific name. Thus, Binomial System of Nomenclature can be defined as the scientific method of assigning two names, i.e. generic name and specific name to an organism. In Binomial system, both names are usually Greek (Gk.) or Latin (L.) or have Latin endings. The scientific names are unique, understood and followed all over the world. S.N. Organisms Scientific names (in Binomial system) 1. Human being Homo sapiens 2. Frog Rana tigrina 3. Mustard plant Brassica campestris 4. Maize plant Zea mays 5. Tiger Panthera tigris 6. Mango Mangifera indica Rules of writing scientific names in Binomial System 1. The name of the genus is written first with its first letter in capital and the name of the species is written after the generic name with its first letter in small. 2. The binomial should be printed in italics or underlined separately if handwritten. For example, the scientific name of lion is Panthera leo or Panthera leo. Fact File Scientific names are not changed easily and are guided by a set of rules stated in the International Code of Biological Nomenclature (ICBN).

64 Oasis School Science and Technology - 8 Reasonable Facts Binomial system of nomenclature is very important for classification. Binomial system of nomenclature is very important for classification because it helps to bring uniformity in nomenclature of species throughout the world. It simplifies learning. Activity 1 Visit botanical garden or zoo or any other places with guardians and find out scientific names of 10 species. Genus A genus is the group of closely related species resembling each other. For example, all true cats like lion, tiger and domestic cat are kept in the same genus Panthera or Felis. Species A species is the group of closely related organisms which are almost identical in their anatomy, physiology and behaviour and can interbreed to produce fertile offspring. Members of a species also often resemble each other very closely in appearance. For example, all types of human beings throughout the world are kept in same species sapiens. Thus, a species is the group of similar organisms that are able to breed together and produce fertile offspring. Texa Classification of living organisms is done by arranging all organisms into various groups or categories called taxa on the basis of their similarities or differences. Two Kingdom System Classification The two kingdom system of classification was introduced by Sir Carlous Von Linnaeus in 1758. He broadly divided living organism into two groups. They are plants and animals. Plant kingdom was named Regnum Vegetable and animal kingdom was named Regnum Animale. The kingdoms were further divided into sun kingdoms, divisions, phyla and classes. Two kingdom system was first scientific system of classification and it made study of organisms easier. However it is discarded now because it could not classify microorganisms, prokarytoic organisms and fungi. Features of two-kingdom system of classification i. First of all, living organisms are split into kingdoms like Plant Kingdom and Animal Kingdom. Those kingdoms are divided into a large number of smaller groups called phyla (singular-phylum). Then the phyla are further divided into classes, classes into orders, orders into families, families into genera and genera into various species. ii. It is first scientifc classifcation of organisms.

Oasis School Science and Technology - 8 65 Short comings of two-kingdom system classification i. Eukaryotes and prokaryotes are not separated. ii. Plants and fungi are not separated. iii. Unicellular organisms are not separated from multicellular organisms. iv. Autotrophs and heterotrophs are not separated. v. It does not include lichen. Taxa Human being Potato Kingdom Animalia Plantae Phylum / Division Chordata Spermatophyta Sub-phylum / Sub-division Vertebrata Angiospermae Class Mammalia Dicotyledonae Order Primates Polemoniales Family Hominidae Solanaceae Genus Homo Solanum Species sapiens tuberosum Five Kingdom System of Classification We have studied two kingdom system of classification, viz. Plant kingdom and Animal Kingdom. In this unit, you will study five kingdom system of classification of living beings in detail. The concept of Five Kingdom System of Classification was introduced by an American Biologist Robert H. Whittaker in 1969 A.D. Bases for five kingdom system of classification Organisms are grouped into five kingdoms in the five-kingdom classification system. This grouping is based on the following aspects: i. The complexity of cell Structure (Prokaryote or Eukaryote) ii. The complexity of the organism’s Body (Unicellular or Multicellular and Complex) and iii. Mode of their Nutrition (autotrophs and heterotrophs). Features of five-kingdom system of classification i. Prokaryotes and eukaryotes are separated. ii. Unicellular and multicellular organisms are separated. iii. Green plants and non-green plants like algae and fungi are kept in separate groups. Fig: Robert H. Whittaker

66 Oasis School Science and Technology - 8 iv. This system of classification is related to evolution of organisms. So it helps to get clear concept of life style of living beings. According to the concept of 'Five Kingdom System of Classification', living beings are classified as follows: 1. Kingdom Monera This kingdom includes unicellular prokaryotic microscopic organisms. Their cell contains DNA (Deoxyribonucleic Acid) as a nucleus. They may be autotrophs or parasites. Examples: Bacteria, Azotobacter, Blue-green algae, etc. Bacteria Azotobacter Blue-green algae Fig: Monera 2. Kingdom Protista This kingdom includes eukaryotic unicellular organisms. Their cells contain well developed nucleus. Examples: Amoeba, Paramecium, Euglena, etc. Fig: Protists Amoeba Paramecium Euglena Reasonable Facts Amoeba belongs to kingdom protista. Amoeba belongs to the kingdom Protista because it is unicellular eukaryotic organism. Fact File Protista could be heterotrophic or autotrophic.

Oasis School Science and Technology - 8 67 Activity 2 Observe amoeba through compound microscope. 3. Kingdom Fungi This kingdom includes unicellular and multicellular non-green plants. Their body is thalloid (without root, stem and leaf). They derive their food from dead and decaying organic matter. Their mode of nutrition is either saprophytic or parasitic. They reserve food in the form of glycogen. Their cell wall is made of the mixture of chitin and cellulose. Examples: Mushroom, Yeast, Mucor, etc. Fig: Fungus Mushroom Yeast Mucor 4. Kingdom Plantae This kingdom includes different types of non-flowering and flowering plants. Characteristics of Plant Kingdom i. They are mostly multicellular but some are unicellular too. ii. Their cells contain cell wall which is made up of cellulose. iii. They prepare their own food by photosynthesis. So they are called autotrophs. iv. They store food in the form of carbohydrates such as starch. v. They appear green due to the presence of chlorophyll. vi. They may be non-flowering or flowering. Kingdom Plantae is divided into three divisions which are as follows: a. Division Algae b. Division Bryophyta c. Division Tracheophyta 5. Kingdom Animalia This kingdom includes different types of non-chlorophysllus and heterotrophic animals.

68 Oasis School Science and Technology - 8 Characteristics of Animal Kingdom i. They are multicellular, non-chlorophysllus and heterotrophic organisms. ii. Their cells do not contain cell wall and chlorophyll. iii. They cannot prepare their own food. So they are called heterotrophs. Microorganism The earth is inhabited by millions of living organisms. These organisms are broadly classified into plants and animals. Some living beings like blue whale, elephant, etc. are very large while some living beings like bacteria, protozoa, etc. are very small. Microscopic organisms cannot be seen with our naked eyes. These organisms can be seen only under the compound microscope. So, the organisms which cannot be seen with our naked eyes are called microscopic organisms. Most of the microscopic organisms are unicellular, i.e. having only one cell in their bodies. In this unit, you will study about bacteria, viruses and fungi in brief. Bacteria Bacteria (singular-bacterium) are the smallest and most widespread single-celled plant organisms. They were discovered by Anton Van Leeuwenhoek in 1676 AD and the term bacteria was coined by CG Ehrenberg in 1828 AD. Bacteria are the simplest, most primitive and unicellular organisms. They are found everywhere in air, water, soil, food, inside the bodies of living beings, etc. Most bacteria are saprophytes but some are autotrophs. Characteristics of bacteria i. They have prokaryotic cell. ii. They lack well developed nucleus and many cell organelles. iii. They have a cell wall. iv. They may live alone or in colonies. v. They reproduce asexually by fission. vi. Most bacteria are immotile but some bacteria like bacilli and spirilla can move. vii. They show autotrophic as well as heterotrophic nutrition. viii. Their size ranges between 0.5 to 5 micrometres. Reasonable Facts Bacteria are very useful in dairy industries. Bacteria are very useful in dairy industries because bacteria help in ripening and flavour of cheese, yogurt, creams etc. Fig: bacterium Fact File Some bacteria can survive in ice and some in boiling water.

Oasis School Science and Technology - 8 69 Activity 3 Get a cup of milk and make a curd from it. Economic importance of bacteria Bacteria have both useful as well as harmful effects. a. Useful effects of bacteria i. Some bacteria like Rhizobium, Nitrobacter, Nitrosomonas, etc. regulate nitrogen cycle and help to increase the fertility of soil. ii. Most bacteria act on dead bodies and decompose them which helps to recycle materials in the environment. iii. In industries, bacteria are used in curding of milk, tanning of leather, production of vinegar, cheese making, and processing of coffee, tobacco, etc. iv. Many bacteria are used for making medicines like antibiotics. v. Many bacteria live in our intestine and help in digestion of cellulose. b. Harmful effects of bacteria i. Bacteria cause many harmful diseases in plants, animals and human beings. They cause diseases in potato, maize, paddy, etc. and damage them. In humans, bacteria cause diseases like typhoid, tuberculosis, leprosy, cholera, tetanus, pneumonia, dysentery, etc. ii. They spoil milk, meat, vegetables and other food items. iii. Some bacteria cause food poisoning by releasing toxins into spoiled food. iv. Some bacteria (denitrifying bacteria) reduce the fertility of soil. Viruses Viruses are the smallest and possibly the most primitive, acellular, non-protoplasmic bodies. The word virus has been derived from a Latin word venom which means poison or poisonous fluid. Viruses are much smaller than bacteria, and can be detected only under the electron microscope. The size of viruses ranges from 25 nanometers (nm) to 250 nanometers [1nm = 10-9m]. On an average, viruses are about 50 times smaller than bacteria. In 1886 AD, Meyer first described the viral disease of tobacco and called it 'tobacco mosaic'. All viruses are totally parasitic and behave like living organisms inside the living host cell, while they are quite inactive and seem to be dead out of the host cell. Therefore, viruses Fig: flu virus

70 Oasis School Science and Technology - 8 are placed on the boundary of the living world and non-living world. Viruses have different shapes like spherical, cylindrical, hexagonal, etc. Viruses do not have cellular structure, i.e. they do not have cell membrane or cell organelles. They are simply made of nucleic acid (either DNA or RNA) which remains surrounded by coat of proteins (a thin film of protein). Viruses can exist outside the living cell for a long period of time but they cannot reproduce outside the living cell. Since viruses can reproduce only inside the living cell of the host, they are called obligatory parasites. Living properties of Viruses i. Viruses contain genetic material, i.e. either DNA or RNA. ii. Viruses can reproduce in a large number and they transmit hereditary characteristics to their offspring. iii. Viruses infect living organisms and cause various diseases. Non-living properties of Viruses i. They do not have a cellular structure. ii. They do not perform metabolic activities. iii. Viruses can be crystallized like non-living things. iv. They become inert and cannot reproduce outside the living cell. Viruses - The agents of diseases Viruses cause a wide range of diseases among living organisms. A few hundred plant diseases caused by viruses have been recorded so far. For example, mosaic disease of tobacco, cabbage, cauliflower, mustard, etc; black ring spot of cabbage, leaf roll of tomato, etc. Similarly, disease caused by viruses in human beings include AIDS, polio, mumps, common cold, rabies, measles, chicken pox, swine flu, etc. Activity 4 Find a picture of bacteriophage virus and make its 3 D modal. Differences between Bacteria and Viruses S.N. Bacteria S.N. Viruses 1. Bacteria are very small in size. They can be seen under a compound microscope. 1. Viruses are smaller than bacteria. They can be seen only under an electron microscope. 2. Bacteria show metabolic activities. 2. Viruses do not show metabolic activities. Fact File COVID-19 pandemic was caused by the virus named SARS-CoV-2.

Oasis School Science and Technology - 8 71 3. Bacteria are living cellular organisms. 3. Viruses are acellular particles. However, they show living properties only inside the host. 4. A bacterial cell is surrounded by a distinct cell wall. 4. Cell wall is absent in viruses. Reasonable Facts Viruses are called obligatory parasites. Viruses can exist outside the living cell for a long period of time but they cannot reproduce outside the living cell. Since viruses can reproduce only inside the specific cell of the living host, they are called obligatory parasites. Reasonable Facts Viruses are kept in the borderline of living beings and non-living things. Viruses show the properties of both living beings and non-living things. So, viruses are kept in the borderline of the living beings and non-living things. Fungi Fungi are non-green thallophytes without chlorophyll. They are distributed throughout the world. They grow in dark and moist places on the surface of dead and decaying organic matter. Mushroom, yeast and moulds (Mucor, Rhizopus, etc.) are some examples of fungi. Moulds can be observed as they grow on food, bread, leather, fruits, barks of trees, etc. Fungi cannot prepare their own food due to the absence of chlorophyll. They get their food from dead and decaying organic matter. So, they are called saprophytes. However, some fungi are parasites of plants and animals. Fig: Fungi Mushroom Yeast Bread mould

72 Oasis School Science and Technology - 8 Characteristics of fungi i. Fungi contain eukaryotic cells which may contain more than one nucleus. ii. The plant body is a thallus, i.e. without root, stem and leaves. iii. Their cell wall is made of fungus cellulose. iv. They do not have chlorophyll. v. Their body is made of hyphae, i.e. long filaments or mycelia. vi. They may be unicellular (yeast) or multicellular (mushroom). vii. They reproduce asexually by budding, fragmentation and sporulation. Economic importance of fungi a. Useful effects of fungi i. Fungi act on dead bodies and decompose them. Thus, they help to increase the fertility of soil and recycle materials in the environment. ii. Some fungi, i.e. edible mushrooms are valuable food sources for human beings. iii. Some fungi like yeast are used in wine industries and bakeries. iv. Some fungi like penicillin are used as antibiotics. b. Harmful effects of fungi i. Fungi attack tissue of plants and animals and cause diseases. ii. Fungi infect humans and cause diseases like skin infection, vaginal yeast infection, etc. iii. Many fungi attack food grains and vegetables and spoil them. Differences between Bacteria and Fungi S.N. Bacteria S.N. Fungi 1. They have prokaryotic cell. 1 They have eukaryotic cell. 2. They are unicellular. 2 They may be unicellular or multicellular. 3. Nuclear membrane is absent. 3 Nuclear membrane is present. 4. They have autotrophic and heterotrophic nutrition. 4 They have heterotrophic nutrition. Amoeba Amoeba is a species of protista kingdom. It is unicellular, eukaryotic and aquatic organism. It is found in water, moist soil, food and as a parasite too. Fig: amoeba

Oasis School Science and Technology - 8 73 Amoeba is irregular in shape. It locomotes by the help of pseudopodia. Pseudopodia also helps to trap food. Food is digested at food vacuole and waste is removed by contractile vacuole. Entamoeba histolytica is a parasitic amoeba which causes amoebic dysentries (amoebiasis) in humans. Nagaleria fowleri is a free living amoeba but can cause diseases to humans if enters our body. Methods of Food Preservation We can’t live without food. So, food is the most essential for all of us to survive. Millions of tons of food spoil each day. The Food and Agriculture Organization estimates that 25,000 people per day pass away from illnesses brought on by malnutrition and starvation. Our top priority is to use food wisely. You should never throw away food. Numerous factors, including bacteria, yeast, fungi, light, temperature, moisture, etc., cause food to spoil in large quantities. To avoid food spoilage, we can use a variety of techniques. Dry preservation, wet preservation and cold preservation are used to prevent food spoilage. A. Dry preservation The process of removing water from food is known as dehydration. Food is typically spread out in the sun to accomplish this. To dry food by capturing solar heat, a solar food dryer can be used. Otherwise, food is dried in the sun, such as grains, seeds, mustards, etc. To remove moisture, vegetables like radish, carrot, squash, etc. are sliced and dried in the sun. Green leafy vegetables like spinach and lettuce, among others, can also be dried. Fish and meat are occasionally also dried and kept in storage. The food loses moisture during drying. In dry food, fungi and bacteria cannot grow. So they are unable to spoil food. Reasonable Facts Grains are dried in sunshine before storing. Grains are dried in sunshine before storing to remove moisture so that bacteria and fungi won’t damage it. Activity 5 Gather some rice or other crops when it's time to harvest them from the ground. Foodstuffs should be stored both moist and sun-dried. After one week, compare the two. Fact File Dehydration means to remove water and moisture from the food. It reduces microbial activities.

74 Oasis School Science and Technology - 8 B. Cold preservation Food spoilage can be avoided using the very common technique of freezing. Food preservation is typically done in a refrigerator in the kitchen. It is frequently used in restaurants, stores, grocery stores, etc. to stop food from spoiling. Because bacteria do not thrive in cold temperatures, freezing can significantly reduce the risk of food spoilage. So, the food in the refrigerator is essentially undamaged. C. Wet preservation Microbial activity can be controlled by the oil, vinegar, and glycerol. The oil keeps the moisture out. Due to its low pH, vinegar kills germs. Glycerine is a sweet, viscous liquid with antimicrobial properties. So, food spoilage can be avoided by using oil, vinegar, and glycerine. Reasonable Facts Oil is used as preservative. Oil prevents food from absorbing moisture, so it is used as a preservative. Therefore, it reduces microbial activity. Food spoilage can be avoided using one or more of the above methods. For example, radish is cut, dried, and combined with salt and oil to be stored. After that, it is canned and sun-dried. It is kept in a pickled form. Activity 6 Get some radish and make pickles. Food can also be preserved by following ways a. Salting Salting is a common method for the preservation of food. Salt is an item that dissolves in water. Salt draws moisture from the food when it is added to dishes like pickles. Bacteria are unable to reproduce when there is a decrease in moisture. Food won't spoil because there are fewer bacteria present. Food spoilage can be avoided by salting food. b. Sweetening Sweetening is the process of preserving food by incorporating sugar into it. Sugar regulates the amount of moisture in food and lowers microbial activity. In foods like jam and jelly, it stops or slows the growth of bacteria, moulds, and yeast. Some moulds are resilient, though. They can also flourish on jam. Fact File Acid is present in vinegar. It has a low pH. It does not support the growth of bacteria. Consequently, it can be used to preserve food. Fact File Foods may be stored in a sugar syrup or cooked in sugar until they crystallise.

Oasis School Science and Technology - 8 75 Reasonable Facts Even though sugar is mixed in jam some moulds still grow in it. Jam still has some mold growth in it even though sugar is added because molds are resilient. Molds will expand if the sugar concentration is low. Activity 7 Find some fruits, and then slice them thinly. Bring a cup of water to boil and add a lot of sugar to it. Stir in the fruits and sugar syrup. Let the fruit dry after it has been dusted with sugar. Keep some for a week and watch what happens. Does it deteriorate or not? Boiling Germs in food are destroyed by boiling. Boiling can stop food from spoiling. Sometimes food is boiled and canned, like tomatoes and other fruits. Food is kept fresh because there are no pathogens. To keep the mushroom from rotting, it is boiled and dried before storage. Milk can also be boiled to kill germs. Milk is preserved longer when it has been boiled. Canning Food items like fish, seafood, fruits, dairy products, etc. are "boiled and dried," and then mixed with oil or preservatives. Food is stored in the container after air has been removed from it. It is known as canning. Reasonable Facts Canned food is dried and sterilized. To eliminate moisture and eradicate bacteria, canned food is dried and sterilized. Reasonable Thinking Skill Reasonable Thinking Skill R T S 1. Is the classification of organisms really necessary? Yes, the classification of the organism is necessary because: i. Organisms will be kept in various groups and subgroups based on their traits. ii. New found organisms can be classified easily. iii. It won’t be necessary to study each organism individually. iv. Proper classification can be used for the scientific study of the organism. v. Proper classification can help us to notice phylogenetic relations, evolutionary history etc.

76 Oasis School Science and Technology - 8 2. Bacteria are spread in sewage in many countries by the municipality. Sewage is wastewater. It contains many degradable wastes such as stool, urine, laundry waste etc. To manage this waste, bacteria are spread in sewage in many countries by the municipality. This is because bacteria help in decomposition. Waste will be decomposed faster so that minerals will return to the earth, and water becomes clean faster. 3. Why do many people say we originated from a monkey? Many people say we are originated from the monkey because monkeys have many physical traits that are similar to humans. But, it is not true that we evolved from present monkeys. 4. Fungi are now removed from the plant kingdom. Why was it placed in the plant kingdom? Why is it not classified as a plant anymore? Fungi are now removed from the plant kingdom but it was placed in the plant kingdom earlier because: i. It is definitely not an animal so the only other kingdom it could be on the twokingdom system is the plant kingdom. ii. It has a cell wall. iii. It absorbs nutrients from decaying organic materials from the ground which is similar to the plants. Fungi is not classified as a plant anymore in the five-kingdom system of classification because: i. Its cell wall is made of chitin but the plant's cell wall is made of cellulose. ii. It is saprophytic whereas plants are autotrophic. iii. It does not have chlorophyll whereas plants have chlorophyll for photosynthesis. 5. Radha has an infection in her throat. It is a bacterial infection. Certain bacteria are harmful to us. Make a list of some other harmful effects of bacteria. Bacteria can sometimes be trouble for us. Some harmful effects of bacteria are listed below: i. Bacteria can spoil stored food, milk, meat and vegetables. ii. They can cause deadly diseases such as typhoid, cholera, pneumonia etc. iii. They can cause diseases to our crops and domestic animals. iv. They can make land infertile by removing nitrates from the soil. 6. Many foods are perishable. They rot away pretty soon. Farmers are at a loss if they cannot sell it on time. What is responsible for food spoilage? What are the other harmful effects of those microbes? What can be done to prevent food spoilage? Farmers lose a great sum of money if they cannot sell their products in time. This is because most foods are perishable. They rot away faster. Microbes such as bacteria, yeast and moulds are responsible for food spoilage. Despite ood spoilage, microbes are responsible for many other harmful activities. Some of them are:

Oasis School Science and Technology - 8 77 i. They can cause diseases in plants and animals. ii. They can make us sick. We can do the following things to prevent food spoilage: i. Dehydration: Lack of moisture reduces microbial activities. ii. Freezing: : Microbes are mostly inactive at lower temperatures. iii. Sweetening : Sugar regulates moisture and reduces microbial activity. iv. Salting : Salts absorb moisture from food and sometimes from bacteria and make them inactive. v. Boiling : Boiling kills bacteria. vi. Canning : Canned food won’t decay because there are no bacteria in cans. vii. Using vinegar: Acidic environment reduces microbial activity. 7. In Nepal, farmers usually collect spinach, mustard leaves, radish, etc. They squash and dry them so that they can consume them during winters when the food is scarce. Why won’t food go bad when dried? It is common in Nepal to collect spinach, mustard leaves, radish, etc. They squash and sun dry them so that they can be used in winter. Sun-dried foods usually last for many months. It won’t go bad because sun drying removes moisture from the food. Since there is no moisture, microbes such as bacteria and yeast won’t grow well. Their population won’t increase and most of them stay inactive. As a result, dry foods won’t rot due to reduced microbial activity. 8. Write any two major differences between Monera and Protista. The differences between Monera and Protista are listed below: SN Monera SN Protista 1. Organisms of the Monera kingdom have prokaryotic cells. 1. Organisms of the protista kingdom have eukaryotic cells. 2. All organisms of the Monera kingdom have a rigid cell wall. 2. Most organisms of the Protista kingdom do not have a cell wall. Exercises 1. Choose the best answer from the given alternatives. a. Which of the following is acellular? i. virus ii. amoeba iii. yeast iv. rhizobium b. What is a group of closely related breeds called? i. species ii. genus iii. kingdom iv. class

78 Oasis School Science and Technology - 8 c. Why is denitrifying bacteria harmful to the soil? i. It decays the root. ii. It removes nitrates from the soil. iii. It causes diseases in the plants. iv. It produces a bad smell. d. How does vinegar preserve food? i. It prevents oxidation. ii. It keeps food dry. iii. It helps to ripen the fruit. iv. It slows down the growth of the bacterial population e. Which species do human belong to? i. Homo sapiens ii. Homo iii. Sapiens iv. Erectus 2. Define the following with required examples. a. Classification b. Taxonomy c. Nomenclature d. Binomial system of nomenclature e. Genus f. Species g. Monera h. Protista i. Fungi j. Plantae k. Animalia l. Bacteria m. Virus n. Five kingdom system of classification 3. Very short answers a. Which organism in the English language is known as Magnifera indica? b. Which kingdom does azotobacter belong to? c. What are thallus, white, vegetative part of fungi called? d. What is the objective of mixing sugar while making jam? e. What is the primary objective of sun-drying food? 4. Give reasons. a. Linnaeus is called the father of taxonomy. b. Classification of living things is very important. c. Five kingdom system of classification is more scientific than the two- kingdom system of classification. d. We should not eat moist food from the grounds. e. Viruses are called obligatory parasites. f. Virus is called the borderline between living and non-living. g. Bacteria are very important for the environment. h. Fungi are called decomposers. i. Radishes are cut and dried before storing. j. Adding sugar helps to prevent food from decaying for a few months.

Oasis School Science and Technology - 8 79 k. Boiled and canned food lasts for many years. l. It is difficult to see viruses even through microscopes. m. Salt is added to pickles. 5. Differentiate between : a. Genus and species b. Bacteria and amoeba c. Fungi and algae d. Plantae and Animalia e. Bacteria and virus 6. Short questions a. Enlist the importance of classification. b. What are the similarities and differences between the species of the same genus? c. Enlist the shortcomings of the two-kingdom system of classification. d. On what basis five-kingdom system is formed? e. Write down some salient features of the plant kingdom. f. Enlist the properties of micro-organisms. g. What are the physical features of fungi. h. How does the use of Chuuk amilo help to preserve pickles? i. Enlist the features of monera and protista. 7. Long questions a. How is a scientific name given to an organism? Describe with an example. b. Mention any four reasons to show that the five-kingdom system is far better than the two-kingdom system of classification. c. Describe the structure of the bacteria and draw a labelled diagram. d. Describe the structure of the virus. e. How does a virus fit in the living as well as the non-living world? Describe with the help of its properties. f. Educate people that a virus is an agent of diseases. g. Discuss the economic importance of fungi. h. What can be done to prevent food from decaying? Enlist possible ways and describe any three. i. Life is impossible without bacteria. Justify. j. Life any four positive and four negative effects of micro-organisms.

80 Oasis School Science and Technology - 8 UNIT 4 ENVIRONMENT AND BIODIVERSITY Estimated teaching periods Theory 6 Practical 2  Introduction and importance of biodiversity  Status of biodiversity in Nepal  Causes of biodiversity declination and control measures of biodiversity declination  Introduction and importance of sustainable development  Principles of sustainable development  Objectives of sustainable development.  National efforts for sustainable development. The Sequence of Curriculum Issued by CDC Raymond Fredric Dasmann is well known for his idea of sustainable development. He was born in San Francisco on May 27, 1919, and died on November 5, 2002. He was an American biologist and environment conservationist. He helped to develop the concept of eco-development and biodiversity and identified the importance of recognizing indigenous people and their culture in conserving natural landscapes. About the Scientist Raymond Fredric Dasmann Key terms and terminologies 1. Environment : The physical and biological world where we live is called the environment. 2. Development : The process by which members of society increase their personal and institutional capabilities is called development. 3. Sustainable development: The development that meets the needs of the present without compromising the availability for future generations to meet their own needs is called sustainable development. 4. Biodiversity : The measure of the variety of organisms present in different ecosystems is called biodiversity. 5. Ecosystem diversity : The variation in the self-sustaining systems in which there is an interaction between biotic and abiotic components is called an ecosystem diversity.

Oasis School Science and Technology - 8 81 7. Species diversity : The presence of multiple species and differences among them living in a particular environment is called species diversity. 8. Genetic diversity : The variation in the hereditary units that transfer parental characteristics to their offspring is called genetic diversity. 9. Nature-friendly development: The development carried out without affecting nature and its resources is called nature-friendly development. 10. Habitat : The place where a species is born, grows and lives is called its habitat. Introduction Our surrounding consists of physical world and biological world. The physical and biological world where we live is called environment. It is a natural world in which human beings, animals and plants live together. Our environment consists of physical surroundings including climatic factors and living organisms. The physical surroundings which make up the environment are air, soil and water. The climatic factors that form a part of environment are sunlight, temperature, pressure, rainfall, wind, etc. Environment is the totality of physical, biological, natural, social, economic, chemical and cultural aspects. It is clearly seen that there is a continuous interaction between or among these aspects. The change or interaction between or among these aspects is responsible for the change in environment. Therefore, we can say that there is a continuous change in environment due to the change in its components. Human beings are also a part of the environment. All activities of human beings have a great impact on the environment. Today we do not live in a natural environment as we have modified it to suit our needs. Biodiversity A variety of plants and animals are found in our surroundings. The plants and animals are different from each other. Plants and animals are different in shape, size, behaviour, habitat, life cycle, reproduction, etc. Their diversity and types of ecosystems explain biodiversity. It is diversity in life. According to Convention on Biological Diversity (CBD) Biodiversity is the degree of variation of life. It is a measure of the variety of organisms present in different ecosystems. It should be noted that biodiversity is the short form of biological diversity. Reasonable Facts Biodiversity is very important for humans. Biodiversity is very important for humans because it is a source of food, raw materials, crops etc for us. Types of Biodiversity Biodiversity refers to the genetic variation, ecosystem variation and species variation within an area, biome or earth. Hence, biodiversity can be mainly classified into three types. Broadly biodiversity is divided as floral diversity and faunal diversity. Floral diversity Fact File Almost a million species of plants and animals are endangered in earth.

82 Oasis School Science and Technology - 8 means the presence of diverse species of plants in a particular ecosystem. Faunal diversity means presence of diverse species of animals of particular ecosystem. i. Ecosystem diversity Ecosystem diversity refers to the diversity of a place at the level of ecosystems. Ecosystem diversity is the variation on the self-sustaining systems in which there is interaction between biotic and abiotic components. There are mainly two types of ecosystems, viz. terrestrial and aquatic. Aquatic ecosystems include river, stream, lake, pond, sea, ocean, etc. whereas terrestrial ecosystems include forest, grassland, desert, shrub-land, etc. It is recorded that there are 118 different types of ecosystems in Nepal. Due to climatic and geographical variation, various kinds of ecosystems are found in Nepal. Similarly, different types of animals are found in Nepal due to ecosystem diversity. ii. Species diversity Species is the group of individuals which can freely interbreed with each other to produce fertile offspring. There are different kinds of species in our surroundings. Cow, goat, dog, cat, etc. are some examples of animal species. Mustard plant, wheat plant, rice plant, etc. are some examples of plant species. Plants and animals are different within themselves. Cows and buffaloes both are mammals but they have so many dissimilar characteristics. So, cows and buffaloes are kept in different species. It is the variation in the group of individuals which can interbreed freely with each other. The variation among the organisms of different species is called species diversity. iii. Genetic diversity Genes are the hereditary units that transfer parental characteristics to their offspring. Genes are located in chromosomes. Children have characteristics similar to their parents. These characteristics are called hereditary characteristics. But, there is variation among the children of the same parents. Such variation is called genetic diversity. Genetic diversity is the variation in the hereditary units that transfer parental characteristics to their offspring. Genetic diversity depends on the population of the organisms. Genetic diversity refers to the variation among the members of the same species, e.g. Nigro, Mangol, Aryan, etc. are different breeds of same human species. Fig. 24.1 Species diversity Fig. 24.2

Oasis School Science and Technology - 8 83 Differences between Ecosystem diversity and species diversity Ecosystem diversity Species diversity 1. It is the variation on the self sustaining systems in which there is interaction between biotic and abiotic components. 1. It is the variation among the organisms of different species. 2. It refers to the diversity of a place at the level of an ecosystem. 2. It refers to the variation of different kinds of species in our surroundings. Differences between Species diversity and Genetic diversity Species diversity Genetic diversity 1. It is the variation among the organisms of different species. 1. It is the variation in the hereditary units that transfer parental characteristics to their offspring. 2. It refers to the variation of different kinds of species of our surroundings. 2. It refers to the variation among the members of the same species. Activity 1 Visit a nearby ecosystem with your science teacher. Identify various kinds of species found in that ecosystem. Prepare a short report on it and submit to your science teacher. Importance of biodiversity i. Biodiversity at the genetic level results in slight variations among the members of the same species. It helps organisms to survive well in their environment. ii. Presence of multiple diverse species helps to continue the food chain in the ecosystem. iii. Presence of microscopic bacteria and yeast helps to decompose dead organisms and return minerals to the earth. iv. Most of the medicine we use comes from different species of plants and animals. v. Trees, bushes and wetlands store water and prevent the flood. It purifies water. vi. Insects and birds pollinate crops. vii. Biodiversity is the source of food, shelter and oxygen for all life forms. viii. Biodiversity develops job opportunities for local people. It is a source of revenue for a country. Present Status of Biodiversity in Nepal In Nepal, there are more than 185 species of wild animals and more than 886 species of birds. Tiger, Rhinoceros, Snow leopard, Deer, Kasturi, Badel, Jackal, etc. are the major wild animals found in Nepal. Similarly, Kalij, Titra, Danphe, Munal, Koel, Eagle, etc. are some main birds found in Nepal. 26 species of mammals, 9 species of birds and 3 species

84 Oasis School Science and Technology - 8 of reptiles are protected in Nepal. Most of the animals and birds live in the forest. In Nepal, there is rapid deforestation due to population growth. Nepalese people encroach forest land to expand settlement and to get agricultural land. They cut down trees for firewood, timber, fodder, etc. Some people also involve in illegal hunting of wild animals and birds. As a result, many species of animals and birds are on the verge of extinction. The number of Elephant, Rhinoceros, Tiger, Wild buffalo, Snow leopard, Musk deer, etc. is decreasing day by day. Similarly, animals like Black buck, Hispid hare, etc. are on the verge of extinction. Therefore, we should conserve the forest to protect the habitat of wild animals. Some groups of plants found in the world and in Nepal Group of Plants Found in the world Found in Nepal Percentage in Nepal Lichen More than 17,000 850 5 Algae 56,579 1,001 1.76 Fungi 98,998 2,467 2.45 Bryophytes 16,236 1,213 7.47 Pteridophytes 12,000 580 4.83 Gymnosperms 1,021 41 4 Angiosperms 369,400 6,973 1.87 Source: Adhikari (2016), Shrestha (2018), Chaudhary ( 1996), Pradhan(2016), Mieche (2015) et.all. Some animal species found in the world and in Nepal Group of animal Found in the world Found in Nepal Percentage in Nepal Mammals More than 4,765 185 3.96 Aves 9,799 886 8.90 Reptiles 7,870 78 0.99 Amphibia 4,780 118 2.47 Fish 10,000 187 1.87 Butterfly 17,500 651 3.27 Spider 39,490 175 0.44 Source: Nepal Government, Department of National park & wildlife conservation (2019), Bird-life International (2006), IUCN (2003) et.all. Loss of Biodiversity Every single organism in the ecosystem serves a very specific purpose. However, as a result of human activity, the vast majority of species is either in threat of extinction or is vulnerable with it. The term "loss of biodiversity" refers to the process through which the number of any species in a certain region decreases to the point where that species is either threatened, endangered, or becomes extinct. The majority of the decline in biodiversity can be attributed to actions performed by humans.

Oasis School Science and Technology - 8 85 Causes of loss of biodiversity i. Poaching and illegal wildlife trade is threat to biodiversity Poaching is encouraged by lax regulations, a lack of education, low incomes, and illegal trades. Poaching refers to the illegal killing of wild animals or the illegal collection of wild vegetation by humans. People can be seen hunting uncommon wild creatures or gathering rare species of plants in order to make a livelihood from the products of their labor. It poses a significant danger to the world's various forms of life. ii. Human-wildlife conflict decrease population of wild animals Many individuals make their homes in the surroundings of forest areas. They gather food from the forest, which consists of firewood, grass, and other fruits. The wild creatures will occasionally wander into the village and cause damage to the people, the crops, and the infrastructure. When people need to eat, they would sometimes hunt animals in the wild. It has a deleterious impact on the world's diverse ecosystems. iii. Invasion by alien species disturbs local ecosystem. Agricultural lands and farms can sometimes be the source of the spread of exotic or genetically modified plants and animals into surrounding environments such as rivers, forests, and other natural areas. They then proceed to proliferate to the point that the new ecology can no longer support their presence. iv. Poisonous substance used in agriculture kills hundreds of animals The rainfall washes the chemical fertilizer off the fields and into the river, where it is dissolved. Because of the algae's rapid growth, the water will have insufficient oxygen levels throughout the nighttime hours. It can kill aquatic animals. v. Chemical insecticides and pesticides Chemical insecticides and pesticides are toxic compounds that are used to control insects. They will not only eliminate destructive insects, but also beneficial ones. They are capable of killing not only mammals but also birds and rodents. Therefore, there will be a change to the environment as a result. vi. Over-harvesting resources and mining disturbs local ecosystem The forest is exploited by humans for its many timbers and medicinal plants. Marble is mined from hills, gravel is gathered from river bottoms, and so on. The overexploitation of these natural resources is one of the primary factors contributing to the loss of biodiversity. vii. Deforestation destroys habitat of wild animals Both urbanization and industrialization are primary factors to the loss of forest cover. Forests are cleared to make room for agricultural land, residential areas, furniture, papers, and herb gardens. Deforestation is the process of removing large swaths of forest from a region. Deforestation, excessive grazing, and forest fires are three of the most significant factors contributing to the habitat loss of wild animals. Because of the destruction of habitat, dozens, if not hundreds, of plant and animal species will become extinct.

86 Oasis School Science and Technology - 8 viii. Climate change makes it harder for organism to survive The local weather and seasons are both affected when there is a shift in the climate. The average temperature of a location will continue to climb. There will be a disruption in the water cycle. As a direct consequence of this, it will be exceedingly challenging for creatures to continue existing in the natural environment to which they are adapted. Reasonable Facts Deforestation is the main cause of declination of biodiversity. Deforestation causes biodiversity to decline because animals lose shelter, food, and water. Ecosystem collapses and population declines. Activity 2 Many villagers collected firewood from the forest. They also collect grass from the forest to feed their cows. If the population of the village is doubled, how will it affect the ecosystem? Discuss. Measures of Conservation of Biodiversity It is essential that biodiversity be conserved given that it is the fundamental factor that enables the continued existence of every living thing. In Nepal's Interim Constitution from 2007, the government is required to make unique provisions for the protection of the country's diverse biological resources. Some ways to conserve biodiversity are: i. Enabling policies, strategies and regulatory framework To prevent poaching, illegal wood smuggling, excessive herb collection, etc., strict rules and regulations and well-planned measures are required. ii. Participation in international conventions The government ought to take part in international conventions for the preservation of biodiversity. They will supply the necessary information, plans, and funds to preserve biological variety. iii. Establishment and management of protected areas There are many different types of protected areas; some examples are national parks, hunting reserves, wildlife reserves, and conservation areas. These locations discourage human intrusion into the surrounding forest. It safeguards the flora, animals, and ecological system of the region. iv. Management of forest outside protected area The local population should be permitted to use and watch over the forest. The protection of the forest is helped by the practices of afforestation and reforestation of deforested land. Areas of the forest that have been encroached upon the need to be regained. There would be no drop in the amount of biodiversity when the forest area is protected. Fact File A biodiversity hotspot is a richly biodiversity area under major risks.

Oasis School Science and Technology - 8 87 v. In-situ and Ex-situ Conservation of Biodiversity The efforts made to preserve biodiversity in its native environment are referred to as "in-situ conservation." It is possible to practice in-situ conservation on individual species as well as on ecosystems in their totality. In-situ protection of biodiversity can be seen, for instance, in the form of protected areas, botanical gardens, and national herbaria. The Central Zoo is an example of biodiversity conservation that occurs outside of its natural habitat. Some species are propagated in environments that are not their natural home. They are under the care of humans for a predetermined amount of time before they are allowed to return to their natural habitat. vi. Public participation The participation of local people is necessary for any attempt to preserve the earth's natural biodiversity. Their means of survival are closely bound up with the natural environment of the area. Therefore, it is our responsibility to bring to their attention the significance of the preservation of biodiversity. It is our responsibility to educate them on how to make use of the forest and the resources it provides without causing any damage to the forest. It is imperative that we take steps to lessen the amount of tension that exists between humans, wildlife, and the government. It is possible to encourage ecotourism, which, in addition to assisting local people in earning a living, also assists in the preservation of biological diversity. Reasonable Facts Restricting people from collecting a bounty of forest does not help to conserve biodiversity. Restricting forest bounty does not assist preserve biodiversity because it makes people's daily lives more difficult. So they steal wood, steal medicine, and hunt animals. This will reduce biodiversity. Activity 3 What can we do as a member of society to preserve the biodiversity in our nearby surroundings? Discuss. Concept of Sustainable Development We should conduct development activities in accordance with the bearing capacity of natural resources without affecting the environment. Natural resources should not be used excessively to satisfy the demands of increasing population. Excessive use of natural resources affects environment adversely and it will be difficult for animals to live. The concept of sustainable development has been developed to prevent the problems that will arise in the future. Fact File The Amazon has already lost 17% of its forest cover and an additional 17 % of its rain forests have been degraded.

88 Oasis School Science and Technology - 8 Sustainable development is the combination of two words ‘sustainable’ and 'development'. Sustainable means capable of being around for a long time and development means growth. Therefore, in other words, sustainable development is related to those developmental activities which do not degrade the environment and can be carried on for a long time. Thus, sustainable development includes: i. living within the limits of consumption of natural resources, ii. realizing the interconnections among various developmental aspects and environment, and iii. equitable distribution of resources and opportunities. Therefore, according to Brundland commission formed in 1987, sustainable development refers to the use of natural resources at present without damaging their condition for the future generations. Sustainable development is also called retaining development or bearable development. The main objective of sustainable development is to maintain balance among population, natural resources, components of environment and development. Sustainable development does not degrade the environment. It helps maintain the natural resources for a long time. As a result, environment remains in balanced condition. It does not affect the life cycle of the living beings. Thus, sustainable development is the need of the world. The benefit of sustainable development can be achieved in local, national and international level. Reasonable Facts Sustainable development is the need of the country. Sustainable development is the need of the country because it conserves natural resources for future generation by relying on the renewing capacity of resources Activity 4 • Observe any one of the developmental works among road, bridge, building, etc. in your locality. On the basis of your observation, find out the answers to the following questions: • What natural resources are used in that developmental work? • What are the adverse effects of that development work on the environment? • On the basis of the solutions to above questions, prepare a short report and submit to your subject teacher. Aspects of sustainable development Sustainable development is based on three major pillars; the environment, the economy and the society. Fact File Raymond Fredric Dasmann is well known for his idea of sustainable development.

Oasis School Science and Technology - 8 89 a. Environmental aspect i. Developmental activities should not harm wild animals. ii. Developmental activities should conserve natural resources. iii. We should conserve environment while making roads, house etc. iv. We should focus on minimising deforestation, natural disasters etc. b. Social aspect i. Social harmony, equality and education helps to promote sustainable development. ii. Public participation, production of skilled manpower is important for sustainable development. iii. Poverty elimination helps to promote sustainable development. c. Economic aspect i. Sustainable development focus in stable economic growth. ii. It focus on equal distribution of natural resources for every community. iii. It helps to create job and benefits for us and for future generation. Principles of Sustainable Development The main principles of sustainable development are discussed below: i. Conservation of ecosystem There are mainly two types of ecosystems on the earth. They are an aquatic and terrestrial ecosystem. When there is conservation of the aquatic and terrestrial ecosystem, there is conservation of the earth itself. Hence, the ecosystem should be conserved. ii. Development of a sustainable society Healthy habitat, balanced diet, health services, quality education and job opportunities are some elements of a sustainable society. These elements develop a positive attitude towards nature and motivate people to the conservation of environment. iii. Conservation of biodiversity Conservation of biodiversity is a must for sustainable development. Conservation programmes should be conducted at the local, national and global levels. iv. Control of population growth Population growth should be controlled for meeting the goal of sustainable development. It means that a balance should be maintained between population growth and environmental resources. v. Development of human resource There is a need for the development of human resources for sustainable development. It is because only trained, qualified or skilled manpower can implement the principles of sustainable development effectively.

90 Oasis School Science and Technology - 8 vi. Increase public participation Public participation is necessary for sustainable development. With an increase in public participation, objectives of sustainable development can be easily achieved. There is a need for the joint effort of all the people in conservation programs. vii. Conservation of cultural heritages Cultural heritages are an important aspect of the environment. Conservation of cultural heritages contributes to implement principles of sustainable development. viii. Limit of carrying capacity The carrying capacity of the earth means the maximum number of individuals that the earth can sustain. Human activities should be conducted within the carrying capacity of the earth. That means, people should understand the regeneration processes of mother nature. The importance of sustainable development The importance of sustainable development includes: 1. Sustainable development helps in renewing the natural resources. 2. It is an environment friendly method of development. So, it does not harm the environment. 3. It helps to meet the essential needs for jobs, food, energy, water, and sanitation. 4. It helps to conserve the natural resources. 5. It ensures the ability of the future generation to meet the needs of development Sustainable development helps to conduct development activities with minimal effect to the environment. If we follow the principles of sustainable development, we can continue our development works without harming the environment. Differences between Development and Sustainable development Development Sustainable development 1. It is a process by which members of society increase their personal and institutional capabilities. 1. It is the development that meets the needs of the present without compromising the availability of future generations to meet their own needs. 2. Development meets the needs of the present generations only to meet their own need. 2. Sustainable development meets the needs of the present generation and future generation without compromising the availability to meet their own need. Nature–Friendly Development The main aim of sustainable development is to protect nature and natural resources with their wise and judicious use. It is necessary to protect nature, environment and its components for sustainable development. Developmental works should be carried out without destroying nature and its resources. The development carried out without affecting nature and its resources is called nature– friendly development. We should conduct development activities according to the bearing capacity of the natural resources and environment.

Oasis School Science and Technology - 8 91 Conservation and promotion of nature and its resources is the common duty and responsibility of all human beings. Some human activities promote the environment while some activities of human beings affect the environment adversely. We should either stop or modify the developmental activities that affect the environment to reduce their impact on the environment. Nature–friendly development not only conserves nature but also helps satisfy needs of human beings. It also saves natural environment. According to the concept of sustainable development, economic benefit should be gained with a limited use of natural resources. In order to make developmental activities nature–friendly, following points should be taken into consideration. Activities for Nature - Friendly Development i. We should reduce air pollution The amount of harmful gases in atmosphere is increasing day by day due to increase in the number of industries, factories and vehicles. Unmanaged industries, increase in number of vehicles, wastes of humans and animals are major sources of air pollution. To reduce air pollution, we should develop technologies that reduce the emission of poisonous gases from vehicles and industries. We should establish factories and industries away from human settlement. We should reduce the use of fossil fuels, insecticides and pesticides to control air pollution. It helps to conserve the environment. ii. We should conserve water resources Living beings cannot survive without water. Water is the basis of life. Therefore, we should conserve water resources. We should not destroy water resources while constructing roads, buildings, factories, etc. We should plant trees around the sources of water. We should reduce water pollution. It helps to conserve water resources and natural environment. iii. We should conserve land Nowadays people are using cultivable land for housing and establishing cities and industries due to population growth. It may bring crisis of land for farming which leads to food crisis in the near future. So, it is necessary to conserve land for farming. Similarly, we should plant tress on slopes and bare land. We should manage waste materials properly to reduce land pollution. iv. We should conserve rivers, lakes and other water resources Water resources are getting deteriorated due to human activities. We are facing water crisis in urban as well as rural areas. Many development activities affect water resources adversely. Therefore, development activities should be conducted by conserving water resources like river, lake, wetland, watershed, etc. In this way, we should conduct development activities without affecting air, water and land. Such development lasts long and becomes sustainable. Nowadays, it is compulsory to conduct development activities only after environmental impact assessment (EIA).

92 Oasis School Science and Technology - 8 Goals of Sustainable Development The 2023 agenda for sustainable development has described its certain goals. There are 17 Sustainable Development Goals (SDGs). It ensures the blueprint for peace and prosperity for humans, other life forms, the environment and the planet for today and tomorrow. In 1992 more than 178 countries adopted Agenda 21 to build a global partnership to protect the environment and human lives. In 2015, at UN Sustainable Development Summit, the 2030 Agenda for Sustainable Development was formed. It contained 17 SDGs and 169 targets. The goals and targets started in 2015 and will continue to work up to 2030. The SDG focuses on people, the planet, prosperity, peace and partnership. The 15th goals of SDG focus on the wise use, protection and promotion of terrestrial ecosystem. It tries to prevent desertification, conserve the forest, prevent soil erosion and conserve biodiversity. Some common objectives of SDG regarding environment and biodiversity are food security, clean drinking water for all, sanitation, infrastructure, climate change adaptation and mitigation and sustainable management of coastal and marine resources. According to the global circulation model, imbalance in the environment of one place will definitely hamper the environment of another place. So, every country must work together to meet the SDGs. The effort of Nepal to meet SDGs Nepal has formed multiple committees that are working to meet SDGs. The following activities are carried out for this purpose: i. Nepal has launched community development programs for poverty elimination, biodiversity conservation, education for all, sanitation etc. from 2016-2019 to meet SDGs. ii. Nepal formed a climate change council in 2009 to adapt and mitigate the impact of climate change. This council constructed a dam and a drain to prevent the bursting of Tsho Rolpa (altitude: 4,580 meters) glacial lake in 2020. They also conducted many cabinet meetings on Kalapatthar (altitude: 5550 m) and Rara lake (altitude: 2990 m) for public awareness about water resources and challenges. iii. Nepal launched a community forest in 1970. It is a successful model to protect the forest, wild lives and environment at the local level. It is observed that the forest area is increasing considerably after the local people were allowed to manage their forest based on the community forest act in 1993. iv. 15th plan of Nepal guarantees a clean, pure and green environment for all. It also deals with waste management and promotes greenery. v. The Environment Protection Act, 2019 (2076) was made by the government with the following objective: 1. Modify and use the current laws on the environment to protect the right of the people to live in a clean, green and healthy environment. 2. The person or company that pollutes the environment must pay compensation to the victim.

Oasis School Science and Technology - 8 93 3. We must maintain a balance between the environment and development. 4. We must reduce the harmful impact on the environment and biodiversity. 5. We must adapt or mitigate the harmful impacts of climate change. Activity Observe various activities conducted by local people for ten days. Which of these activities promote sustainable development ? Write with suitable reason. Project Work • Prepare a short report after observing the development activities in your locality. Explain with reason whether these activities are nature–friendly or not. Reasonable Thinking Skill Reasonable Thinking Skill R T S 1. Discuss the importance of sustainable development. Development is for the present but sustainable development is for the future. Some of the importance of sustainable development are: i. Appropriate use of available natural resources of the country. ii. Sense of responsibility and public participation in development activities. iii. Emphasis on the development of basic aspects such as health, education and agriculture. iv. Considers the carrying capacity of the earth while launching developmental activities. v. It has a long-term vision. It utilises available natural resources in such a way that our future generations also can use them. 2. Introduce biodiversity as a source of food for all. The totality of all life forms, species, genes and ecosystems is called biodiversity. It is a source of food for all life forms. i. Various species of plants and animals are the source of food for human beings. ii. Organisms could be producers, consumers or decomposers. They form a food chain. iii. Genetic diversity of crops and domestic animals are used in breeding to produce various food we eat today. iv. Many plants and animals reproduce, which is the source of new food in the ecosystem. 3. Discuss the interrelationship between environment and development. Environment and development are interrelated. Some of their interrelations are mentioned below: i. Environment provides the raw material for development.

94 Oasis School Science and Technology - 8 ii. Development of society does not last long without conserving the environment. iii. Conflict between development and the environment is harmful to humans, wildlife and the environment. iv. Developmental activities launched by considering the carrying capacity of the earth. The development and environment will be sustainable and beneficial for humans and the environment. 4. Differentiate between sustainable development and development. The differences between sustainable development and development are: SN Sustainable development SN Development 1. The development that meets the needs of the present without compromising the availability of future generations to meet their own needs is called sustainable development. 1. The process by which members of society increase their personal and institutional capabilities is called development. 2. It is good for the environment, humans and wildlife. 2. It could be harmful to the environment, wildlife and human health. 5. Nepal is a developing country. Numerous infrastructural development activities are launched each year. Are there any around your locality? Are they environmentally friendly or not? Discuss. Since Nepal is a developing country, numerous infrastructure development activities are launched each year. Some developmental activities that are happening around my locality are the construction of roads, drinking water supply, drainage, electricity lines etc. Most of them are environment-friendly development projects because: i. They are not destroying the forest. ii. Many local people are taking part in it. iii. Available natural resources are utilized properly. Even though sustainable development is focused. It is still insufficient because of a lack of budget, skilled manpower and technology in the country. 6. Nepal is rich in biodiversity. Explain. Nepal is rich in biodiversity because: i. Its altitude ranges from 60 meters to 8848 meters giving rise to varieties of weather and climate. ii. More than 181 types of different ecosystems are discovered in Nepal. iii. Numerous species of living things are found in Nepal. For example, there are 170 species of wild animals and 860 species of birds in Nepal. iv. Nepal has various breeds of each species. For example, Nepal has achhame, lulu, terai, pahadi and chauri breeds of cows. 7. Unmanaged urbanization and industrialization have increased the rate of loss of biodiversity. Unmanaged urbanization and industrialization are harmful to the environment, wild lives and human health.

Oasis School Science and Technology - 8 95 It is one of the many causes of loss of biodiversity because: i. It causes deforestation. Many species of plants and animals lose their habitat and source of food to deforestation. ii. It causes air pollution. Organisms suffer from various diseases due to environmental pollution. iii. Human-wildlife conflict also pushes wild lives toward extinction. iv. Unmanaged cities are overpopulated. They harvest resources and mine minerals that disturb the ecosystem. Many species go extinct due to disturbances in the ecosystem. v. It causes climate change. Climate change is very harmful to the ecosystem and everyone in it. 8. If you were the prime minister of Nepal, what would you do to encourage sustainable development? Write any three points. If I were the prime minister of Nepal, I would do the following things to encourage sustainable development in my country. i. I would discourage deforestation and encourage plantation. ii. I would increase the number of wildlife reserves and national parks. iii. I would focus on eco-tourism. iv. I would try to increase public participation in development activities. v. I would request related organizations to work effectively for environment conservation. Exercises 1. Choose the best answer from the given alternatives. a. What is the presence of multiple types of ecosystems in a particular area called? i. species diversity ii. rich biodiversity ii. ecosystem diversity iv. genetic diversity b. How many species of mammals are found in Nepal? i. 26 ii. 9 iii. 185 iv. 60 c. What is the act of utilising natural resources without degrading their quality for future generations called? i. development ii. eco-friendly development iii. nature-friendly development iv. sustainable development d. When was sustainable development introduced? i. 1972 ii. 1945 iii. 1989 iv. 2062 e. Which of the following is not the principle of sustainable development? i. conservation of biodiversity ii. conservation of ecosystem iii. pollution reduction iv. population growth

96 Oasis School Science and Technology - 8 2. Define the following terms with required example. a. Environment b. Development c. Sustainable development d. Nature friendly development e. Biodiversity f. Ecosystem diversity g. Species diversity h. Genetic diversity 3. Very short questions a. Give an example of species diversity. b. Where are genes located? c. There are some visible differences between two individuals of the same species. What type of diversity is it? d. How many types of ecosystems are discovered in Nepal? e. What type of development helps to conserve the environment? 4. Give reasons. a. The fluctuation of natural resources results in difficulty in the lives of human beings. b. The proper use of natural resources is closely related to sustainable development. c. Sustainable development is a need of the world. d. All activities of human beings have a great impact on the environment. e. We should reduce pollution. f. Restricting people from collecting a bounty of forest does not help to conserve biodiversity. 5. Differentiate between a. Environment and ecosystem b. Ecosystem diversity and genetic diversity c. Development and sustainable development 6. Short questions a. The participation of local people is necessary for any attempt to preserve the earth's natural biodiversity. Explain. b. Climate change makes it harder for an organism to survive. Clarify. c. Over harvesting resources and mining disturb the local ecosystem. Explain. d. How does human-wildlife conflict decrease the population of wild animals? Explain. e. Poaching and illegal wildlife trade are a threat to biodiversity. Clarify. f. Discuss the principles and concept of sustainable development. 7. Long questions a. Discuss the need and importance of plants and animals for humans. b. What are the causes of loss of biodiversity? Enlist them and describe any four. c. What are the ways to conserve biodiversity? Enlist them and describe any four. d. What are the efforts for sustainable development in our country? e. What are the things that we should take into consideration before launching a developmental activity?