Correct Answer: B. Mutation

Explanation

The primary source of variation in a population is mutation. Mutation is a spontaneous change in the DNA sequence of an organism's genome. It introduces new genetic variations by altering the existing genetic information.

Correct Answer: C. promote sales

Correct Answer: C. government grants

Explanation

(a) Characteristics of manufacturing Industries in Tropical African Countries: (i) Concentrated in towns.

(ii) Mainly import substituting. (iii) Depend on imported machinery/technology. (iv) Mainly light industries.

(v) Labour intensive. (vi) Production of consumer goods (vii) Products mainly consumed internally.

(viii) Mainly small-scale industries. (ix) Some raw materials are imported.

(x) Dominated by foreign multi-national corporations. (xi) Provision of alternative power supply.

(b) Problems of manufacturing industries in my country:

(i) Inadequate capital.

(ii) Shortage of raw materials.

(iii) Poor infrastructure / Inadequate transport/Communication facilities.

(iv) Competition from foreign goods / Smuggling.

(v) Inadequate power supply (vi) Political instability. (vii) Low purchasing power

(viii) Shortage of skilled labour / Technical know-how. (ix) Poor management (x) Preference for foreign goods.

(xi) High cost of production. (xii) Small market for industrial goods. (xiii) High cost of spare parts.

(xiv) Restriction of foreign exchange. (xv) Labour unrest.

(xvi) High taxation / tariffs. (xvii) Shortage of entrepreneurs. (xviii) Poor quality of industrial labour.

Correct Answer: A. m + n = 90°

Correct Answer: D. 0

Explanation

\(\frac{1}{x^2 - 4} = \frac{P}{(x + 2)} + \frac{Q}{(x - 2)}\)

I = p(x - 2) + Q(x + 2)

Let x = 2

I = P(2 - 2) + Q(2+ 2)

I = -4Q

Q = \(\frac{1}{4}\)

Let x = -2

I = P(-2 - 2) + Q(-2 + 2)

I = -4p

P = \(\frac{1}{-4}\)

PQQ = - \(\frac{1}{4} + \frac{1}{4}\)

= 0

Explanation

(a)(i) Excretory organs found in living organisms: Lung, kidney, skin, liver and nephridia

(ii) Lungs - man, Kidney - man, Skin - man, Liver - man, Nephridia - earth worm, Contractile vacuole - paramecium, Stomata / Lenticel - plants, Flame cells - tape worm, Malpigian tubules - insects.

(b)(1) Two ways in which the excretory organ of earth worm is similar to that of mammals are:

(1) Both possess structure for filtering excretory products.

(2) Each is well supplied with blood.

(ii) Differences between mammals and earth worm:

(c) Mechanism of opening and closing of the stomata:Each stoma is enclosed by guard cells. Guard cell has chloroplast and is also elastic. During photosynthesis, sugar is formed and this increases the concentration of cell. sap. Guard cell receives water by means of osmosis and becomes turgid. This makes the stoma to open. During the night, sugar in the guard cell is converted to starch. This makes the osmotic concentration of guard cell to reduce. Water is lost lay the guard cells through osmosis to the surrounding. This makes the guard cell to be flaccid, hence stoma closes.

Correct Answer: D. half its initial potential energy

Correct Answer: D. oestrogen

Correct Answer: B. magnetic meridian

Explanation

The magnetic meridian is an equivalent imaginary line connecting the magnetic south and north poles and can be taken as the horizontal component of magnetic force lines along the surface of the earth. Therefore, a compass needle will be parallel to the magnetic meridian.