Correct Answer: A. suppressed

Explanation

(a) Characteristics of subsistence agriculture in Nigeria: (i) Mixed farming. (ii) Small size of farms/land fragmentation. (iii) Use of family labour.

(iv) Labour intensive. (v) Involves slash and burn method (vi)Yield per hectare is relatively low. (vii) Cultivation is mainly for consumption. (viii) Little attention given to cash crops.

(ix) Farmland abandoned when crop yields decline. (x) Less capital intensive. (xi) Crops include cereals, root crops and legumes, etc. (xii) Organic manure may be used.

(xiii) Crops are seasonal. (ix) Simple farm tools are used. (x) Practiced in regions of low population. (xi) Land is left to fallow. (xii)No specialization. (xiii)Natural i i)Natural control of pests. (xiv) Limited damage to the soil.

(b) Advantages of subsistence agriculture: (i) Low cost of land preparation. (ii) Cheap family labour. (iii) Ease of practice because of small farm size.

(iv) Mixed cropping ensures food security. (v) Mixed cropping checks erosion/leeching. (vi) Burning adds ash to enrich the soil.

(vii) Land regains fertility after period of fallow. (viii) Non-application of artificial fertilizers. (ix)Non-application of pesticides. (x) Crops are normally natural and non-genetically modified.

(xi) Little capital is needed. (xii) Fodder for livestock.

(c) Disadvantages of subsistence agriculture: (i) Burning destroys soil organisms. (ii) Burning alters soil structure.

(iii) Farm sizes are small and may not support large families/communities. (iv) Requires much human energy to practice. (v) Easy spread of diseases.

(vi) Unreliable family labour.

(vii) Easy spread of pests. (viii) Burning results in deforestation and environmental degradation. (ix) Low yield. (x) Cannot be practiced in highly populated areas.

Correct Answer: B. a brand of elitist cigarette

Correct Answer: A. using lady bird beetles to feed on cytoplasm

Correct Answer: B. Thymine

Explanation

In DNA, the four nucleic acid basis are adenine, guanine, cytosine, and thymine. RNA has uracil instead of thymine. Adenine pairs with thymine in DNA and uracil in RNA. Cytosine and Guanine pair together in both. Deoxyribose and ribose are the 5-carbon sugars in DNA and RNA nucleotides, respectively.

Correct Answer: C. Treponema pallidum

Correct Answer: A. positive income elasticity

Correct Answer: C. 619 C.E.

Explanation

(a) Life Cycle of the Liver Fluke (Fasciola hepatica)

Liver fluke: The adult fluke is found in the bile duct of animals where it feeds and reproduces. The adult fluke reproduces eggs in the bile duct of the animal which are pass out with faeces from the primary host (Cattle, sheep etc) If the eggs and faeces are passed out by the ruminant into water, they develop to a larva called miracidium which will later hatch ten days later. This larva swims in the water, looks for a snail which is its secondary host (usually Limnea truncatula). It penetrates the snails skin or the pulmonary hole. It develops to a sporocyst within the snail. Through asexual reproduction the sporocyst reproduces a larva called radial. The radial ruptures from the sporocyst and migrate to the digestive gland of the snail. Here it grows to a final larva called cercaria. After six weeks this cercaria leaves the snail through the pulmonary hole and swims to look for the final host in the water. The cercaria is ingested by the ruminant through infested pasture or water. Then in animal stomach, it makes its way to the animal liver to the bile duct through the liver tissues. It grow to an adult fluke in the animal's bile duct

(b) The life cycle of the fluke can be disrupted by: Eliminating all the snails which are its secondary host in the waters where the ruminant animals drink or feed by spraying copper sulphate solution. Provide clear uninfested waters and feed for the animals. Control weeds along river sides. Periodic burning of pasture to kill eggs in faeces

(c) The Effects of Lice on Animal Production: They cause discomfort and irritation on f animals. They blood from animals leading to anaemia. They reduce production or yield of animals. They create the wounds for secondary infection. They transmit diseases. They reduce feed and water intake. They reduce the growth of animal/cause emaciation. Weaken the animals

Correct Answer: A. I and II only