Explanation

(a)(i) The process of osmoregulation in a named unicellular organism, e.g. Paramecium /Amoeba is as follows: Contractile vacuole carries osmoregulation in paramecium. The cell content of paramecium is hypertonic to the external medium. Therefore water enters, by osmosis into the cytoplasm and later into the contractile vacuole. To prevent the cell from being over turgid and bursting, the contractile vacuole discharges its content from time to time, thereby maintaining water balance within the organism.

(ii) The process of osmoregulation in man begins with the kidney. The kidneys carry out osmoregulation in

man, when the osmotic concentration of blood is higher than that of the cell content, by means of sugar/ Nucleus mineral salts/amino Acids/other plasma solutes. The kidneys extract these substances from the blood/ body cells and absorb more water. When these substances are present in small amounts in the blood there is higher osmotic pressure in body cells, thus decreasing osmotic concentration of the blood. The kidney extracts more water than usual by the action of ADH/hormones and more concentrated urine is produced, thus keeping the osmotic concentrations of blood and cell fairly constant/avoiding any damage. Water can also be lost through sweating and breathing out moist air.

(b) The mammalian skin can react to regulate the body temperature in a hot room. When there is excess heat in the body, blood flow in the dermal capillaries is stimulated and the blood vessels under the skin epidermic dilates whereby more blood is brought to the surface or the sweat picks up the latent heat of vaporization from the skin, cooling the skin down. Heat is also lost by radiation which allows air to flow through the follicles and through convention. The hair lies inclined / flat.

Correct Answer: D) Cu

Correct Answer: D. take charge of local administration.

Correct Answer: D. consumed the burnt offering

Correct Answer: D. stock goods produced by different manufacturer

Correct Answer: B. makes land cheap to acquire

Correct Answer: D. Jean Bodin

Correct Answer: D. 2.0Ω

Explanation

- silting of river mouths

- problems of piracy

- presence of rapids, cataracts, waterfalls/dams

- fluctuations in the volumes of rivers

- presence of water weeds e.g. water hyacinth

- competition with other modes of transport

- slow speed

- freezing of rivers and lakes

- narrow gorges

- shallow nature of most river valleys

- non-flexibility

- presence of dangerous aquatic animals

- adverse weather conditions

- limited capital

- short courses of rivers

- rivers flowing through areas of limited commercial activities

- poor maintenance culture

- low patronage

- hazards of tree stumps

- poor navigational aids

- poor management

The solutions to the constraints are:

- dredging to increase depth of rivers

- traffic control on rivers to check piracy

- channelization to avoid rapids and waterfalls

- removal of water weeds with herbicides/machines

- improving the technology of speed boat engines to increase speed

- dredging of more canals for accessibility

- policing water ways

- use of dams and reservoirs to control water levels

- introduction of comfortable boats

- use of ice breakers

- involvement of conservation to control dangerous animals

- provision of adequate capital

- construction of canals

- development of the hinterland

- cultivation of good maintenance culture

- enlightenment on the use of inland water ways

- removal of tree stamps

- provision of modern navigational aids

- improved management

Correct Answer: C. Rice

Explanation

Rice (Oryza Sativa) needs Silicon (si) for its growth. Choice C is correct.