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(a)(i) Ecological succession: A gradual and orderly change/replacement; of different species of plant and animal communities, in a given area; over a period of time, until the conditions Of the area became gradually modified by their activities, so that a climax/equilibrium/balanced community is reached/established. (ii) Process of ecological succession on a bare piece of land: - The first living organisms on a bare plot of land are the pioneers/algae/mosses as the pioneers live and die they add nutrients to the soil this creates conditions that are more suitable/favourable to other plants/ferns/herbs/lower animals/insects/ worms which could not live there before as they also live and die, their remains improve the soil conditions farther and so perennial herbs/grasses and other animals/lizards, snakes, toads, rats are able to live there subsequently a point is reached at which the soil can support the growth of taller / species/shrubs/ trees and higher animals and higher animals/birds/various mammals may be found at this stage a climax community is established which is in equilibrium with the environment. (b)(i) Biosphere: - Parts of the earth/air, water, soil; in which life exists. (ii) Population: - Total number of organisms; of the same species; which live in a given area; at a given time. (iii) Community: -A group of different living organisms/ population; living together in a habitat; and interacting with each other. (iv) Ecosystem: - A natural unit; made up of living organisms and their non-living components; interacting together; to produce a stable system. (c)(i) Instrument or measuring relative humidity: Hygrometer/wet-dry bulb/paper hygrometer. (ii) Instrument for measuring wind speed: Anemometer.

(a)(i) Conservation: Planned/wise/judicious use/management of the earth's natural resources; in order to ensure sustenance/availability/continuity; and preservation of the quality of the natural/original nature of the environment. (ii) Factors responsible for decline of abundance and variety of wildlife: Commercial hunting which kills off animals indiscriminately industrialization which involves clearing of forests for various purposes/construction/farming/urbanization destruction of habitats of wildlife by human activities bush burning/noise pollution leads to wildlife migration environmental pollution which releases dangerous materials that degrades environment making it unbearable for the wildlife massive/excessive tree felling to make charcoal/domestic uses lack of awareness/inadequate education of populace on the need for conservation lack of adequate funding to enforce conservation policy. (b) Ways by which the Government can improve the situation: establishment of forestry departments establishment of Environment Protection Agency to improve the situation creation of Parks and Games Reserves/any correctly named example; to preserve/maintain plants and animals in their natural environment conservation education carried out through tree planting! campaigns against bush burning/ tree felling /poaching conservation laws to regulate tree felling; poaching/hunting of wild animals and bush burning establishment of zoological gardens preserving endangered species. (c)(i) Eutrophication: Excessive growth of plant life/algae/algal bloom; in water courses/bodies, caused by an increase in organic nutrients and minerals; leading to the death of aquatic organisms. (ii) Causes of eutrophication: Overuse of fertilisers/plant nutrients which drain off into water bodies; sewage discharge; was from fish farming.

(a) Description of the carbon cycle: Carbon occurs in the air/atmosphere/as carbon dioxide/dissolved in the oceans/seas/water bodies; and is circulated continuously; through the activity of microorganisms/ decay bacteria/saprophytic organisms/fungi; which decompose the dead organisms; plants/animals release carbon dioxide and water; the carbon dioxide released increases the concentration of carbon in the atmosphere/ocean/sea/water bodies; this is further increased by respiration in plants and animals; combustion of wood/coal/peat/oil/fuel; some of the excess carbon dioxide is absorbed by the sea/water bodies and also used by plants in photosynthesis; organisms in seas/oceans/wafer bodies release carbon dioxide into the atmosphere/water. (b) Functions of; (i) Nitrogen-Fixing Bacteria; Nitrogen fixing bacteria in the nodules of legumes; those living freely in soil; convert atmospheric nitrogen; into ammonia/ammonium compounds. (ii) Nitrifying Bacteria: They live freely in the soil; oxidize/breakdown the ammonium compounds; to nitrites; which are then oxidized by others/Nitrobacter/named bacteria; to nitrates. (iii) Denitrifying Bacteria: They live freely in the soil; these break down/oxidise ammonium compounds; into nitrogen; and oxygen; which is released into the atmosphere.

(a)(i) Excretion: The elimination of waste products; of metabolism; from the body of an organism. (ii) Excretory organs in Humans with their waste products. Excretory Organs in humans Waste Products Kidney - Nitrogenous wastes/urea/water/salts/urine Skin - Urea/SaltsNVater/Sweat Liver - Bile/excess cholesterol Lungs - CO2/water vapour. (b) Functioning of kidney as excretory: Blood from the renal artery enters the bowman's capsule; through the afferent arteriole; ultra filtration occurs in the Bowman's capsule; high pressure in the glomerulus causes the filtration of small molecules/amino acids/ glucose/ minerals salts/ water/ urea; out of the blood plasma into the cavity of the capsule; the filtrate/glomerular filtrate passes through the nephron; where selective reabsorption of useful metabolites/glucose/amino acids take place; in the descending/first proximal convoluted/coiled tubule; the reabsorption of salts and water is regulated in the loop of Henle; and the ascending/second/distal convoluted tubule/large waste molecules like creatine secreted at loop of Henle; depending on blood concentration; the filtrate continues into the main collecting duct/tube; where further reabsorption of water and salt takes place; the remaining fluid in the duct becomes urine. (c) Excretory organs in; (i) Insects → Malpighian tubules (ii) Earthworm →Nephridia/Nephridium

a)(i) Phylum of specimens A and D A- cassava/Sugar/Sweet Potato. Tracheophvta/Angiospermatophyta/Angiospemophyta/Spermatophyta D-Spirogyra-Thallophyta/Chlorophyta. (ii) Habitat of specimen A and D:Habitat of A=Land/Grassland/Garden. Habitat of D=Stream/ponds/puddles/ditches. (b)(i) Type common to all specimens: A sexual/vegetative Reproduction (ii) Method of Reproduction Reason Cassava-Cutting/stem cutting Presence of buds Plantain-Sucker Presence of axillary buds/buds Runner of grass-runners Presence of terminal buds on stem/rhizome Spirogyra-Fragmentation Cells joined end to end on the filaments ( C) observable differences between specimen B and C (Banana Sucker and Runner of grass) Specimen B (Banana Sucker) Specimen C (Runner of Grass) Erect/vertical stem Horizontal/creeping stem Thick/Swollen stem Slender/thin/narrow stem Internode not conspicuous Internode is conspicuous

(a)(i) Life process in mammals associated with specimen F: -External Respiration/Respiration/ Gaseous exchange/Breathing. (ii)Similarities between Specimens E and F: - both richly supplied with blood capillaries/vascularised, -both have thin surface; both are moist, both have large surface area. (b)i)Habitat of specimen F: Land/ terrestrial/Moist place Pond (ii) Observable features that adapt specimen F to its habitat: -Streamlined body for ease movement in water, - Webbed digits of hind limb(s) for swimming -Presence of poisonous gland for protection against predators -Muscular long hind limbs for hopping/jumping: -Stout short forelimbs for absorbing shock on landing. -large bulging eyes for wide vision. -Moist skin for gaseous for exchange/breathing/respiration (c)(i)Observation: cortex stained blue-black, starch present in the cortex. (ii)Part of stem where food is stored: cortex/parenchyma (iii) Tissues for transportation in G: Xylem; phloem (iv) Supporting Tissues in Gi; Collenechyme, scelerenechyme, xylem, parenchyma.

\(\frac{3\sqrt{5} \times 4\sqrt{6}}{2 \sqrt{3} \times 3\sqrt{2}}\) = \(\frac{\sqrt{5} \times 2\sqrt{6}}{\sqrt{2} \times \sqrt{3}}\) = \(\frac{\sqrt{5} \times 2 \sqrt{6}}{\sqrt{6}}\) = 2\(\sqrt{5}\)

(a)(i) R is the required region. (iii) Coordinates of the point of intersection of the two graphs = (1.1, 3.8) (b) Assuming \(y - \frac{3x}{4} = 3\) If x = 0, \(y - \frac{3}{4}(0) = 3 \implies y = 3\) If y = 0, \(0 - \frac{3}{4}x = 3 \implies -3x = 12 ; x = - 4\) x 0 -4 y 3 0 Assuming \(y + 2x = 6\) If x = 0, \(y + 2(0) = 6 \implies y = 6\) If y = 0, \(0 + 2x = 6 \implies 2x = 6 ; x = 3\) x 0 3 y 6 0 (b) \((x + 2)(x + c) = x^{2} + 2x + cx + 2c\) \(x^{2} + (2 + c)x + 2c = x^{2} + bx + 18\) \( 2c = 18 ; c = 9\) \(b = 2 + c = 2 + 9 = 11\) (b, c) = (11, 9).

Q = I2Rt I = \(\sqrt{\frac{Q}{Rt}}\) = \(\sqrt{\frac{8000}{12 \times 20}}\) = 5.8

Concave/converging mirror: * produces a virtual image when object distance(u) exceeds its focal length(f). \(\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\) \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\) \(\frac{1}{15} - \frac{1}{10} = \frac{2 - 3}{30}\) \(\frac{1}{v} = \frac{-1}{30}\) v = -30cm( virtual image) but m = \(\frac{v}{u} = \frac{30}{10} = 3\) Note that the negative sign only shows the placement of the image. It does not affect the magnification.

The ground state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron.

General Gas Equation: \(\frac{P_1 V_1}{T_1}\) = \(\frac{P_2 V_2}{T_2}\) where P\(_1\) = 765 - 5 = 760mmhg \(V_2 = \frac{P_1 V_1 T_2}{P_2 T_1}\) \(V_2 = \frac{760 * 50 * 273}{ 760 * 283}\) → 48.23cm\(^3\)

: To remove oil paints, the use of chemicals is usually required, including turpentine, acetone, kerosene, and various paint thinners.

First, convert to base 10 112\(_6\) = (1 x 6\(^2\)) + (1 x 6\(^1\)) + (2 x 6\(^0\)) = 36 + 6 + 2 = 44\(_{10}\) \(\begin{array}{c|c} 3 & 44 \\ \hline 3 & 14 & r 2 \\ \hline 3 & 4 & r 2 \\ \hline 3 & 1 & r 1 \\ \hline 3 & 0 & r 1 \end{array}\) Ans = 1122 = D

\(\frac{2\frac{2}{3} \times 1\frac{1}{2}}{4\frac{4}{5}}\) \(\frac{8}{3} \times \frac{3}{2} \div \frac{24}{5}\) \(\frac{8}{3} \times \frac{3}{2} \times \frac{5}{24}\) \(\frac{5}{6}\)