Observation

The question required knowledge on hormones and nervous system in general body coordination. Many students displayed their knowledge of hormones and the impact they have on the body. Some candidates could state the differences between hormonal and nervous coordination.
Many candidates could not state what happens to the mammalian hormone after performing its function.
 Majority of the candidates could not also describe the role of auxins in geotropism.

The expected answers are:

(a) Differences between hormonal coordination and nervous coordination

S/No.	Hormonal Coordination	Nervous coordination
i.	Messages are carried chemically	Messages are electrical and chemical
ii.	Messages are carried by the blood stream	Messages are carried by the nerves/neurones
iii.	Respones to stimulus is slower/slow	Response to stimulus is faster/fast
iv.	Responses last for a long time	Responses are short-lived
v.	Activities are controlled by involuntary actions	Activities are under voluntary and involuntary actions
vi.	Responses are widespread	Responses are localized
vii.	Present in plants and animals	Present in only animals
viii.	Hormones are carried to all parts of the body	Nerve impulses are transmittable to a particular location

 

          

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: points must correspond to score

Functions of:
(i)     Follicle Stimulating Hormone

 

• Responsible for the growth of Graafian follicle in females;
• Responsible for sperm development/spermatogenesis;
• Stimulates sex organs to secrete hormones;
• Stimulates development of sex organs.                                      

 

    (ii)    Antidiuretic Hormone

• Induces water reabsorption in the kidney tubules/promotes osmoregulation;
• Increases blood pressure by constricting blood capillaries.         

 

    (iii)   Adrenaline

• Increases the rate of heartbeat;
• Reduces blood flow to the gut/skin/constriction of arterioles;
• Increases blood flow to the brain/muscle;
• Stimulates breakdown of glycogen to glucose for energy production;
• Stimulates the nervous system for alertness/emergency;
• Dilation of the pupils;
• Increases metabolic rate/increases breathing rate.                      

 

(c)        Fate of a mammalian hormone after performing its function

• It is broken down/degraded;
• excreted.                                                                                      

 

(d)       Role of auxin in geotropism

• auxin produced at the terminal bud of shoots and root apices/tips;
• under the influence of gravity;
• is distributed to the lower part of the plant body lying horizontally;
• the high auxin concentration inhibits the growth at the lower half of roots;
• increases elongation in the upper part;
• bending the root downwards/positive geotropism;
• increases the growth rate of cells in the shoot at the lower half;
• inhibits growth rate of cells in the upper half of the shoot causing upward curvature of the shoot/negative geotropism.