Answers

1. Ganglion

Grey matter Dorsal root

Central canal

2.

Receptor cell

Direction of impulse

Cell body

axon

Myelin sheath

Synaptic terminals

(a)

P :afferent neurone

3(a) (i)

Direction of impulse

Dendrite

Q :efferent neurone

Mitochondria provide the energy (ATP) to run the synaptic process.

(ii)

Alzheimer, Parkinson

(b)

When an impulse reaches at the synapse, it releases a chemical substance called a neurotransmitter. The neurotransmitter diffuses across the synaptic cleft to the dendrite of the nearby neurone. In the

dendrite, the neurotransmitter stimulates the neurone to produce new nerve impulse. The new impulse will be carried by this neurone to the next neurone. 4.

Match the following hormones to their functions.

Hormone Antidiuretic hormone (ADH)

Function Stimulate development of male secondary sexual characteristics and spermatogenesis.

Insulin

Stimulates development of the uterine lining and formation of the placenta.

Androgens Prolactin Growth hormone Progesterone

Decreases blood glucose levels and promotes conversion of glucose to glycogen. Stimulates water reabsorption by kidneys. Stimulates milk production and secretion from mammary glands. Stimulates growth, protein synthesis and fat metabolism.

5. Pituitary gland

Thyroid gland

Adrenal gland

Pancreas

Ovary testis

6. The schematic diagram above shows the regulation of blood glucose level. Choose the correct answers for the empty boxes labelled as A, B, C, D and E.

Insulin also stimulates the conversion of glucose to glycogen in B liver and muscle cells, for storage. Glucagon stimulates the liver to break down glycogen to glucose. D Glucagon also promotes lipid breakdown, which releases fatty acids E that can be metabolized for energy. The adipose cells use the breakdown of glucose to form fats. C Insulin stimulates the uptake of glucose by liver, muscle and adipose cells, A for respiration.

7.

P : Ultrafiltration, Q : Reabsorption of glucose, R : Reabsorption of water and mineral salts

8.

(a)

(b) © and

P : synaptic knob Q : synaptic vesicle R :mitochondrion S : neurotransmitter molecule T :receptor molecule U : post-synaptic neurone neurotransmitter Energy expenditure is needed for the synthesis of neurotransmitter the transmission of impulses. This energy is obtained from ATP, generated by mitochondrion during cellular respiration.

(d)

The arrival of an impulse causes the synaptic vesicle to fuse with the membrane of the synaptic knob. Synaptic vesicles release neurotransmitter molecules into the synaptic cleft. The neurotransmitter molecules diffuse across the synaptic cleft.

The neurotransmitter binds to the receptor of the postsynaptic neurone to generate a new impulse. (e)

Neurotransmitter molecules are only produced by synaptic knobs found at the terminal end of axon of an presynaptic neurone.

9.

(a)

10.

L : pituitary gland M : thyroid gland N : adrenal gland O : pancreas

(b)

Testis

©

(i) (ii)

Pituitary gland Thyroid-stimulating hormone

(d)

(i) (ii)

Thyroxine Increases or control basal metabolic rate. Regulates growth and development.

(e)

Iodine is required for synthesis of the hormone thyroxine. Deficiency of the hormone in early childhood causes cretinism. There is retardation in physical growth and mental development.

(a)

(i)

(b)

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(d)

Ultrafiltration (ii) Reabsorption (iii) Tubular secretion

(i)

Ultrafiltration

(ii)

The arteriole diameter is wider than the efferent arteriole. A high hydrostatic pressure is produced which forces the fluid from the glomerulus into the Bowman’s capsule

(i)

Red blood cells, Plasma proteins

(ii)

The large size of the two components do not permit their movement through the small pores in the capillary wall and the inner wall of Bowman’s capsule.

The filtrate flows from Bowman’s capsule to the proximal tubule. In the proximal tubule : - a large volume (about 80%) of the water is reabsorbed - all the glucose and amino acids are reabsorbed

- a small amount of urea is reabsorbed - the filtrate in the loop of Henle is more concentrated, containing no glucose or amino acids but having a higher concentration

11.

(e)

Kidneys

(i)

Describe the reflex action in Figure 7(a)

A sharp pin pierces the skin, causing the sensory receptors in the skin to generate nerve impulses. The nerve impulses are transmitted along an afferent neurone toward the spinal cord. In the spinal cord, the nerve impulses are transmitted from the afferent neurone to an interneurone. From the interneurone, the nerve impulses are transmitted to an efferent neurone. The efferent neurone carries the nerve impulses from the spinal cord to the effector (muscle tissue) so that the pin can be pulled out from the skin immediately. (ii)

Compare the coordination system shown in Figure 7(a) and 7(b).

Comparison

7(a)

7(b)

Efferent pathway

Somatic nervous system

Autonomic nervous system

Stimuli from

External environment

Internal environment

Characteristic

Involuntary actions (reflexes)

Involuntary actions

Muscles/glands involved

Skeletal muscles

Glands, the cardiac muscles of the heart and smooth muscles of the internal organs such as the intestines.

Integrating centre

Spinal cord

Medulla oblongata Hypothalamus

Action

Removing hand from a sharp object, hot stove and kneejerk reflex.

Regulates the internal body processes such as the heartbeats and blood circulation (medulla oblongata)

Regulates the internal environment such as blood sugar level, body temperature and water balance (hypothalamus)