Sashmitha a/p Arun Set A Questions Biology Flipbook Molecules of Life (3)

Set A Questions
Biology Flipbook
Molecules of Life

Name: Sashmitha a/p Arun
Matrics Number: MS2213104492

Practicum: H6T02B
Lecturer name: Azman B. Mohd Noh

Set A Questions
Water Molecules

i. State the main types of molecules of life [5 marks].
ii. With the aid of a labeled diagram, describe the structure of water molecule [10
mark]
iii.Body temperature may rise during hot days. How can sweating help to give
cooling effect for our body? What about animals that do not sweat such as
elephants? Give explanation by applying the concept related to the properties of
water [10 marks].
iv. Water molecules move into or out of cells through osmosis. Explain on osmosis
and compare it with the other types of passive transport [10 marks].

i. State the main types of molecules of life [5 marks].
Water
Carbohydrates
Lipids O

Proteins HH
DNA and RNA Molecules

ii.With the aid of a labeled diagram, describe the structure
of water molecule [10 marks].

Water molecule consists of an oxygen atom & two hydrogen
atoms.It is bonded at an angle of 104.5 due to the repulsion of
two lone pairs of electrons in the oxygen atom.Its oxygen atom
has strong affinity towards electrons and draws electrons
towards itself. The unequal distribution of electrons makes the
oxygen atom is partially negatively charged,while the hydrogen
atoms are partially positively charged .Two hydrogen atoms
form polar covalent bonds which is sharing of electrons with an
oxygen atom.

Water molecule is dipole. The polarity of
water molecules is caused by its high
electronegativity of the oxygen atom
compared to the hydrogen atoms. Water
molecules are held together by a hydrogen
bond. Each water molecule can form
hydrogen bonds with a maximum of four
neighboring water molecules.It is also
formed when a hydrogen atom is attracted to
another strongly electronegative atom such
as (F, O & N. A partial positive (∂+) hydrogen
of one H₂O molecule is attracted to the
partial negative (∂-) oxygen of nearby H₂O
molecule.

iii. Body temperature may rise during hot days. How can sweating help to give cooling
effect for our body? What about animals that do not sweat such as elephants? Give
explanation by applying the concept related to the properties of water [10 marks].

Sweating happens by the principle called heat of vaporization.It takes
energy to evaporate sweat off of the skin, and that energy is heat. As excess
body heat is used to convert beads of sweat into The cooling effect of
perspiration evaporation makes use of the very large heat of vaporization
of water. starts to cool down.Animals such as elephants do not sweat.Thus,
it will bathe or wet themselves with water to prevent their bodies from
overheating during hot days.This is because water has high specific heat
capacity. So it allows to maintain constant temperatures. High amount of
heat energy that must be absorbed to break hydrogen bonds or lost to form
hydrogen bonds for 1 gram of water to change its temperature by 1°C .The
larger the specific heat of a substance, the slower the body heats up.By this
way,it allows the body to be cool and evaporates sweat faster.

The integument of elephants is highly sculptured with
wrinkles and crevices arranged in prominent
geometric patterns. These features are shown to
absorb water and to facilitate its movement over the
body surface of the elephant.Besides it also ensures the
suitable body temperature of the elephants .The
retention of water attributable to epidermal
morphology was quantified by studying latex casts of
integumentary surfaces of the elephants skin.By this
way,one of the properties of water which displays
strong cohesion and adhesion helps elephant to cool
down. The strong cohesion between water molecules
produces a high surface tension. Elephants body which
is not able to absorb water can be aided by the help of
cohesion and adhesion of water this concludes that it
facilitates the body temperature of the elephants.

iv. Water molecules move into or out of cells through
osmosis. Explain on osmosis and compare it with the
other types of passive transport [10 marks].

Osmosis is the movement of water molecules
from a solution with a high water potential of
water molecules to a solution with a low water
potential of water molecules. Osmosis is the
diffusion of water across a semipermeable
membrane. Water readily crosses a
membrane down its potential gradient from
high to low potential. Osmotic pressure is the
force required to prevent water movement
across the semipermeable membrane. Net
water movement continues until its potential
reaches zero.

Types passive transports

There a few types of passive transport such as simple diffusion, osmosis
and facilitated diffusion. Simple diffusion are movement of small or
lipophilic molecules (example: O2, CO2). Osmosis is movement of water
molecules which is dependent on solute concentrations).Facilitated
diffusion is movement of large or charged molecules via membrane
proteins such as channel protein and carrier protein.

comparision between passive transports

Simple diffusion Osmosis Facilitated diffusion

Diffuse across plasma Diffuse through a molecule that need help of
membrane selectively permeable channel protein and
carrier protein
transports oxygen and membrane
carbon dioxide and fat transports water molecules glucose, amino acids and
mineral ions
soluble molecules.

Similarities between osmosis, simple diffusion and facilitated
diffusion.

down the concentration gradient
does not expend energy
occurs through the phospholipid bilayer,carrier protein and
channel protein.