Daniel Leong Yi Heng H2T02A Bio Assignment SB015

BIOLOGY SB015 ASSIGNMENT 2022/2023

BIO FLIPBOOK: MOLECULES OF LIFE & CELL STRUCTURES AND FUNCTIONS (SET A)

Name: Daniel Leong Yi Heng
Matric No: MS2213103972
Practicum: H2T02A
Lecturer’s name: Madam Saliza binti Kadir

QUESTION 1: STATE THE MAIN TYPES OF MOLECULES OF LIFE [5 MARKS]

Nucleic acids : DNA & RNA Molecules of Life
Molecules

Water

Proteins

Lipids Carbohydrates 2

Question 2 STRUCTURE OF A
WATER MOLECULE
Water is a polar molecule
▪ A polar molecule: have opposite Consists of two
hydrogen atoms
charges (unequal distribution
of electrical charge) bonded to an
▪ Oxygen region has a partial oxygen atom
negative charge ( −)
▪ Both the hydrogen regions Two hydrogen
have a partial positive charge atoms form polar
( +) covalent bonds

(sharing of
electrons) with an

oxygen atom

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STRUCTURE OF Regions of neighbouring
WATER MOLECULEs water molecules with

The charged regions in a opposite partial charges are
water molecule are due to its attracted to each other,
forming hydrogen bonds.
polar covalent bond.
Hydrogen
Oxygen can form two bond
hydrogen bonds.
Each water molecule can form
hydrogen bond to several

others, these associations are
constantly changing.

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Angle between the 2 hydrogen atoms Water molecules are held together by Each water molecule can form
is 104.5° hydrogen bond. hydrogen bonds with up to maximum 4
▪ Formed when a hydrogen atom is other water molecules.
▪ 3 atoms form a wide V shape, not ▪ Hydrogen bonds are weaker than
a straight line. attracted to another strongly
electronegative atom (e.g. F, O & N) covalent bonds
▪ A partial positive ( +) hydrogen of ▪ But they are strong enough to hold

one H2O molecule is attracted to the H2O molecules together
partial negative ( −) oxygen of
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nearby H2O molecule

SWEATING HELPS TO Question 3:
GIVE COOLING EFFECT
ON OUR BODY 1. Cooling our body via sweating relies on a properties of water
called latent heat of vaporisation. Latent heat of vaporisation is
Human body works at a particular temperature meant by the heat required to change one mole of liquid at its boiling
range about 98.6 °F (37 °C). Brain functions point under standard atmospheric pressure.
properly when the temperature is normal.
Hypothalamus controls the temperature of the 2. When our body temperature rises above normal range, it will
body. It sends a message to sweat glands to release detected by the thermoreceptors in the hypothalamus or
sweat and cools the body. thermoreceptors in the skin.

3. The sweat glands are stimulated to produce more sweat. Sweat is
also known as perspiration.

4. Heat is absorbed to evaporate sweat, and this cools the skin.

5. High amount of heat energy which is 580 calories of heat is
required or absorbed to turn 1g of water from liquid state into water
vapour.

6. The high latent heat of vaporisation is significance to break the 6
hydrogen bonds between water molecules.

7. Evaporative cooling
occurs. Heat of the body
is then removed by
evaporation of sweat
from the skin surface

9. As the sweat gets vaporized
from the skin surface to the
atmosphere, by absorbing heat
from the body, makes our body
cool down.

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▪ The network of cracks and crevices Elephants don’t have sweat glands so
on the skin of an elephant allows a having as much of their large body
small amount of water to easily covered in water as possible allows
spread and cover a large area of skin. them to cool down via evaporation.

▪ Water spreads through the cracks, Water has high latent heat of
covering ten times more than a flat surface. vaporization. This is because heat
is absorbed to break hydrogen
▪ Elephants also enjoy submerging their bodies in water. bonds so that water evaporate.
Bathing water on itself is also an effective way for these
enormous animals to reduce their body temperature and 8
thus this can prevent overheating.

▪ Water also acts as an adhesive for mud and allows the
animals to cover themselves in layers of mud. This helps to
prevent parasites biting them and also cools them down.

Question 4: Significance of Osmosis:
OSMOSIS Osmosis influences the transport of

Definition: Is a movement of water nutrients and the release of
molecules from higher water potential metabolic products
region to lower water potential region
across a selectively permeable membrane Examples of Osmosis:
The absorption of water from the soil is
until equilibrium is reached. due to osmosis. The plant roots have a

The selectively permeable higher concentration than the soil.
membrane is permeable to Therefore, the water flows into the roots.
water but impermeable to some
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solute such as sucrose
molecules

Similarities

▪ Occurs down the concentration gradient

▪ Occurs until a dynamic equilibrium is achieved

▪ Does not require energy (ATP)

Diffusion Osmosis Facilitated diffusion

▪ Involves small molecules and non- ▪ Only involves water molecules ▪ Involves charged polar or hydrophilic
charged, lipid-soluble & hydrophobic molecule.
molecules. ▪ Occurs through selectively permeable
membrane aquaporins) ▪ Occurs through transport proteins
▪ Occurs with or without the pressure of (carrier or transport proteins)
selectively permeable membrane ▪ For example, transport of water
molecules ▪ For example, transport of glucose,
▪ For example, transport of oxygen and sodium ions, and chloride ions
carbon dioxide

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