Explanation

(a) (i)Competition;is the process by which living organisms in a habitat struggle/compete with one another for limited essential needs such as food/light/nutrients/mates/shelter/space in the environment.

(b)(i) Inter-species competition exists between individuals of different species, e.g. Iroko tree and terminalia in a forest competing for light and competition for grazing land between a herd of cattle and a herd of antelopes on a grazing land.

(ii) Infra - species competitionis the competition between individuals of the same species / kind, e.g. tomato seedlings in a nursery/ a population of laboratory rats in a cage.

(c)(i) The toad is structurally adapted to obtain food by:

(1) possessing special olfactory organ in the head for smelling/perceiving the odour of its food

(2) the ability to draw eyes in so that they make bulges in the roof of the mouth which helps to prevent their prey from escaping/ help in swallowing,

(3) the tongue being attached at the front of the mouth which can be rapidly extended to capture/trap prey

(4) the tongue being long and sticky to help hold the prey

(5) the tongue being long to help catch prey.

(ii) Special adaptation by toad for protection include:

(1)The skin is slimy with mucous gland which makes the animal difficult to catch by predators.

(2) Slimy fluid keeps the skin moist and prevents the skin from drying up.

(3) Toad has poison glands on the skin which is poisonous/ distasteful to the predators.

(4) Brownish colour/cryptic colouration helps to blend with the colour of the surrounding and this prevents them from being noticed by enemies/ predators (5) The colour can be altered to match the type of background.

(iii) special adaptation by toad for movement are:

(1) A toad has long hind limb with powerful muscles which enables it to hop/jump efficiently away from predators/ on land.

(2) The absence of tail facilitates hopping/jumping movement while webbed hind limb can be used as paddle for efficient swimming in water.

(3) The stout/short nature of fore limb absorbs shock on landing

Correct Answer: D. {5, 6}

Explanation

P ∩ Q = {5, 6}

Correct Answer: C. labour force

Explanation

The active population comprises of all persons (both male and female) who make up of the labour force that supplies labour for the production of economic goods and services.

Correct Answer: B. disruption of the processes within the system

Correct Answer: C. scale of preference of the decision maker

Correct Answer: C. the net force acting in uniform linear motion is zero

Explanation

The key point of this law is that if there is no net force resulting from unbalanced forces acting on an object. If all the external forces cancel each other out, then the object will maintain a constant velocity.

Explanation

(a) In the treatment of river water for town supply

(i) Sand bed is used for filtration

(ii) Alum is used for coagulation of suspended particles

(iii) Chlorine is used for killing bacteria/for sterilizing the water.

(b)(i) Major uses H\(_2\)SO\(_4\).

-For the manufacture of fertilizers, pigments, plastics, cellulose films.

-As an electrolyte in batteries

-As a dehydrating agent

-For cleaning metals.

-Petroleum refining

(ii) Blue litmus paper is charred in Conc. H\(_2\)SO\(_4\) because it is dehydrated. In dilute H\(_2\)SO\(_4\), it turns red as a result of the presence of H\(_3\)O\(^+\). It is not charred because dilute H\(_2\)SO\(_4\) does not dehydrate

(iii) Reaction of concentrated H\(_2\)SO\(_4\) with zinc. Zn + 2H\(_2\)SO\(_4\) -> ZnSO\(_4\) + SO\(_4\)+ 2H\(_2\)O.

(c)(i) Gaseous pollutant that can be generated by burning coal are SO\(_2\), NO2\(_2\), CO.

(ii) Coal burns more easily when it is broken into pieces than when it is in lump form becauce the pieces have a larger surface area and the larger this is, the higher the rate of reaction. This could also be explained in terms of particle size.

(iii) The gas that is respo:isible for most of the explosions in coal mines is methane (CH\(_4\))

(iv) Coke is the non-volatile residue of the destructive distillation of coal.

(d)(i) Allotropy is the existence of two or more forms of an element in the same physical state?

(ii) The two crystalline allotropes of carbon are graphite and diamond.

(iii) Other elements which exhibit allotropy are: Sulphur, phosphorus, oxygen, tin

(iv) to calculate the mass of one mole of the fullerene C\(_{60}\) - (12 x 60)g = 720g.

Correct Answer: C. 4,2

Correct Answer: D. Market facilitator

Correct Answer: D. Phosphodiester bond

Explanation

DNA and RNA nucleotides are linked together through phosphodiester bonds. A strong covalent bond (ester bond) forms between the 3' carbon atom of the sugar pentose of one nucleotide and a phosphate group, and a second ester bond forms between the phosphate group and the 5' carbon atom of the sugar pentose of another nucleotide. This alternation of sugar and phosphate groups forms a strong backbone and is also the reason why DNA is antiparallel and forms in the 5' to 3' direction.