Section B

6.a) Z: Carbohydrates-rice ( lm)

Y: Vitamin and minerals- fruits(lm)

X : Proteins- meat ( lm)

Z : Fats-butter ( lm)

(b) At P

Produces bile, which contains bile salts (1).

At Q :

Stores bile (1)

At R

Produces pancreatic juice, which contains amylase, lipase and trypsin (1).

At S:

Amylase hydrolyses starch into maltose:

(i) Starch + water → maltose (1)

(ii) Lipase hydrolyses lipids into fatty acids and glycerol

Lipid + water → fatty acids + glycerol (1)

(iii) Trypsin hydrolyses polypeptides into peptides

Polypeptides + water → peptide (1)

Bile salt emulsifies fats into tiny oil droplets to increase the total surface area for

digestion by enzymes. (1)

(c) A pregnant mother

1. Needs a diet rich in calcium and phosphorus for the formation of strong bones in

the growing foetus (1).

2. Ferum is also needed for the formation of haemoglobin in red blood cells (1).

3. Proteins are also needed for the formation of new tissues of the foetus (1).

4. Vegetables as a source of fibres to prevent constipation (1).

amylase

lipase

trypsin

A child

5. Protein is needed for rapid growth (1).

6. Carbohydrate and lipid are needed to provide energy for the child high basal

metabolic rate (1).

7. Calcium and phosphorus are needed to to form strong bones and teeth (1).

8. Vitamins and minerals for maintaining good health (1).

9. Ferum is needed for formation of haemoglobin (1).

7. (a) (i) Single closed circulatory system - blood passes through the heart only once in a

complete circulation of the body. (2)

Double closed circulatory system - blood passes through the heart twice in each

complete circulation of the body. (2)

(ii) Similarity: Both organisms have closed circulatory system (1) and both organisms

have heart to pump the blood. (1)

Differences:

Aspect Shark Toad

Type of circulatory

systemSingle (1)

Double (1)

Number of chambers in

the heartTwo (1) Three (1)

Number of time the

blood enters the heart in

one complete circulation

Once (1) Twice (1)

Number of atrium and

ventricle

1 atrium/

1 ventricle/

2 atria/

1 ventricle/

b)

PlasmaTissue fluid

Appearance Light yellow (1) Pale straw-coloured fluid (1)

Location Within the blood vessels (1) Outside the vessels,

surrounding the tissue cells

Originate fromWater and dissolved

substances, absorbedPlasma (1)

FunctionTransports over long distance

(1)

Transports over short

distances (1)

Moved by

Pumping of the heart, muscle

contraction and breathing

action

Hydrostatic and osmotic

forces (1)

8.a i)

1. Earthworm has hydrostatic skeleton. The body wall consists longitudinal muscle nad

circular muscle which act antagonistically.

2. When the longitudinal muscles in the posterior end contract and the longitudinal muscle

relax, the segments become shortened. The chaetae anchor the shortened segments in the

posterior end to the soil/ground.

3. When the longitudinal muscles relax and the circular muscles contract, the anterior

segments extend forward. The chaetae in the anterior segments extend to grip the

soil/ground while the chaetae at the posterior end retract and no longer anchor the

segments to the ground

4. The shortened segment in the posterior is pulled forward.

5. Contraction and relaxation of these muscles cause the transfer of hydrostatic pressure

from the front to the end of the body. It causes the body to move to the front.

(ii)

1. a grasshopper has antagonistic muscles called the flexor and extensor muscles which are attached to the interior of the exoskeleton.

2. The rear/ hind legs are bigger and longer and are adapted for jumping.3. In Diagram 8.2(a), flexor muscle contracts to flex the leg/prepare for jumping.4. In Diagram 8.2(b), when the flexor muscle relaxes and extensor muscle contracts, the

rear legs extend and push against the ground.5. In Diagram 8.3(c), the thrust created propels the grasshopper forward and upwards.

b. (i)

1. Biceps is attached to the radius by tendon. When the biceps contracts, the tendons

transmit the pulling force produced by the forearm.

2. At the same time, the triceps relaxes. As a result, the radius is pulled upwards and the

arm is bent.

3. The ligaments that hold the radius, ulna and humerus together enable the radius to be

pulled upwards, bending the arm at the elbow.

4. When the triceps contracts and the biceps relax, the forearm extends or straightens.

5. The triceps that contracts exert a pulling force on the ulna through its tendon.

6. The ulna and radius which are joined to the humerus by the ligaments is pulled

together downwards, causing the arm to straighten.

(ii)

1. Osteoarthritis occurs because the cartilage between the bones is destroyed to wear and

tear.

2. The joints become painful, inflamed, bent and stiff. It usually occurs in joints that

undergo the most stress such as the hip, knee and spine.

Treatments include:

1. Exercise to straighten the affected joints to prevent stiffness

2. Massage on the surrounding muscles using heat therapy/ Take medication to reduce

the inflammation and pain

9.a.(i)

1. The afferent neurone is located between the receptor and central

nervous system (brain or spinal cord).

2. The afferent neurone carries nerve impulses from the receptor to the

brain or spinal cord.

3. The afferent neurone’s dendrite is located at the receptor where the

stimulus can be detected and causes the nerve impulse to be generated.

4. This nerve impulse is carried by the neurone until it reaches the spinal

cord or brain. [Max: 3]

(ii)

1. The synapse is a narrow gap between the axon terminal of a neurone and the dendrite

of another neurone.

2. The synapse is located in the grey matter of the brain or spinal cord.

3. Synapses allow nerve impulses to be transmitted from the axon terminal of a neurone

to the dendrite of another neurone.

4. Nerve impulses are transmitted through synapses with the help of impulse

transmitting substances called neurotransmitters.

5. The neurotransmitter can diffuse across the synapse to the dendrite of another

neurone, and stimulate it to generate its own impulse.

6. This impulse will then be transmitted through this neurone. [Max: 3]

c)

1. When nerve impulses reach at the synapse’s Knob, the nerve impulses stimulate the

vesicle synapse to release neurotransmitter

2. The vesicle membrane fused with presynaptic membrane to release neurotransmitter

3. Mitochondrion produces energy to transport impulses or synthesis impulse

4. Neurotransmitter diffuses across the synaptic deft

5. Neurotransmitter is received by the protein receptor which can be found on the

postsynaptic membrane

6. The information are transferred in the form of chemical impulse

7. Protein receptor will generates new nerve impulses that carries same information