Correct Answer: C. turbidity of water

Explanation

(a) (i) The law of independent assortment states that each member of alleles or contracting character may combine randomly with either member of another pair.

(ii) Findings of Mendel's experiment involving white and red flowered pea plants:-On crossing white and red flowered pea plants, he obtained all red - flowered offspring, but on self-.crossing each of these red- flowered plants he obtained mixtures of red flowered and white flowered plants in the ratio of 3:1 (¾ red / ¼ white flowered).

(iii)Illustrations: Key for parental genotype e.g R for red, r for white

(b) Blood grouping in man is determined by three alternative genes (alleles) A, B, and 0. A person can only possess two (alleles) of the genes on a pair of homologous chromosomes. 0 is recessive to both A and B, hence it is possible to have blood group A and AA (homozygous) and AO (heterozygous) and group B as BB or BO. However, group 0 can only exist genotypically as 00 in the homozygous recessive state.

Correct Answer: D. edaphic

Correct Answer: C. Humidity

Correct Answer: C. carries blood away from the heart

Correct Answer: C. water and organic matter

Correct Answer: D. nucleus

Correct Answer: D. harvested plants in a unit area

Correct Answer: D. provide good health for an individual

Explanation

(a) (i)Pollution;is the release of toxic or harmful substances into the environment by their natural forces or man and other animals to an extent that causes biological damage to man and his resources.

(1) Pollutants of air are:Smoke, fumes, dust, harmful gases e.g sulphurdioxide, hydrogen sulphide, ammonia, chlorine/nitrogen oxides, carbon monoxide, pollen grains and soot.

(2) Pollutants of water are:sewage, excreta/faeces, pesticides, chemical wastes/chemicals from factories, fertilizers, slurry/waste from farms, petroleum/ crude oil, heated water, oil spillage.

(b)(i) Effects of water pollution on organisms are:

(1) Destruction or death of valuable aquatic species such as sea birds, fishes e.t.c.

(2) Food chain is affected, or disrupted.

(3) Pollutants encourage bacterial growth leading to reduced amounts of dissolved oxygen/biological oxygen demand in water. This leads to death of fishes and other organisms.

(4) Causes algae blood or putrification while water is rendered unsafe for domestic, drinking, industrial use or recreation.

(5) It also leads to migration of water animals.

(ii) Ways of preventing water pollution:

(1) There should be efficient and proper sewage disposal system.

(2) Dumping of refuse or petro-chemical by-products into rivers/streams/ponds or seas should be avoided.

(3) The use of efficient techniques to deal with or prevent oil spillage should be adopted.

(4) Industries should be sited away from residential areas and water bodies.

(5) Government /local authorities should strictly monitor all industrial wastes and carry out public enlightenment.

(6) Industrial effluents and hot water should be re-cycled.

(c)(i) Sources of noise pollution are:

(1) Factory or industrial noise.

(2) Aeroplane/aviation noise (taking off and landing of aeroplanes).

(3) Railway engine/locomotive noise.

(4) Automobile/ car horns/sirens.

(5) High pitched musical sounds from loud speakers/drumming.

(6) Noise from mills/sawmills/ grinding mills/electronic gadgets and generators.

(7) Artillary shots /shelling/canon shots.

(8) Thunder noise.

(ii) Effects of noise pollution on man:

(1) Loss of hearing /deafening /hard hearing/hearing difficulty.

(2) Emotional disorder/anxiety / fright and lack of concentration.

(3) High blood pressure/hypertension.

(4) General irritation/short temper.

(5) Changes in behaviour.