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In the symbiotic relationship between fungal hyphae and algae, fungi benefit from the algae's photosynthetic activity, gaining access to sugars (food) produced by the algae, while the algae are protected and can access nutrients from the fungal hyphae. The algae provides the fungus with carbohydrates (energy) and oxygen, while the fungus provides the algae with water and minerals.

The relationship between fungal hyphae and algal plants in lichens is a mutualistic symbiosis, where both organisms benefit from the interaction. The algae (or cyanobacteria) provide food through photosynthesis, while the fungus offers protection and resources.

The correct answer is A - Check desert encroachment. The Sahel region is a transition zone between the Sahara Desert and the savannas to the south, and is vulnerable to desertification. Shelter belts, also known as windbreaks or green belts, are established in the Sahel region to prevent desertification and sand dune encroachment, reduce soil erosion and degradation,protect crops and livestock from harsh winds and sandstorms, and help maintain soil fertility and biodiversity. The other options are not the primary purpose of establishing shelter belts: - Providing wood fuel (B) may be a secondary benefit, but not the main purpose. - Beautifying the region (C) is not a primary goal, although shelter belts can have aesthetic benefits. - Breaking the harmattan wind (D) is a benefit, but not the main purpose. The harmattan is a dry, dusty wind that blows from the Sahara during the winter months.

(a)(i) Features of typical vetebra are: (1) Centrum-solid piece of bone (2) Neural Canal-passage/hole of the spinal cord (3) Neural arch - Forming an arch over the centrum and surrounding the neural canal (4) Neural spine-projects upwards dorsally from the neural arch. (5) Transverse processes - projections from the sides of the neural arch. (6) Facets/articular surfaces for adjacent vertebrae/ zysapophysis. (ii) Types of Skeleton are: (1) Exoskeleton; crabs, centipede, millipede, insects (2) Endoskeleton/any named mammal/human/fish, lizards, birds (3) Hydrostatic skeleton; worms, sea anemone, slug, earthworm, caterpillars, etc. (b)(i) Functions of Mammalian Skeleton are as follows: (1) Protection - gives framework/shape to the body (2) Movement/locomotion - attachment of muscles (3) Support/rigidity (4) Breathing movement (5) Production of red blood cells. (ii) Types of joint in mammal: (1) Immovable/fixed joint - Gliding/sliding joint (2) Ball and socket Pivot joint (3) Hinge joint

(a)(1) Functions of typical foliage leaf are: -Respiration -Excretion -Exchange of gases -Photosynthesis/manufacture of food -Transpiration. (ii) The following are the modifications of leaves and their examples: (1) For (Food) storage; Onion, Garlic, (2) Leaf tendrils; Gloriosa (3) Leaf spines; Cactus, Opuntial Euphorbia, (4) Leaf Hooks; Bignonia (5) Vegetative propagation; Bryophyllum (6)Animal traps; Venus flytrap, Nepenthes/ pitcher plants, Uticularia/ Bladderworts, Sundew, Butterwort, Pinguicula (7) Protective scale leaves; Onions, Shallots, Canna (b) Female reproductive part of a flowering plant (c) Plants pollinated by insects include: Cow pea Nigna unguiculata, Hibiscus, Crotolaria, Flamboyant, Butterfly pea/ Clitoria ternatea, Orchid, Sunflower.

(a)(i) Ecosystem: - This is a self-supporting unit/ system. it consists of all living organisms and the non-living factors, that interact with each other/are interdependent. Each component influences the properties of the others. The living organisms make up the biotic components, e.g. plants and animals The non-living factors make up the abiotic components; e.g. soil/edaphic factors/climatic factors. (ii) Population: This refers to the total number of organisms/individuals of the same kinds/ species living together within a habitat/area at a particular time. The size of the population varies due to different factors; e.g. natality/mortality/immigration/emigration. (iii) Ecological succession in plants: - This is the orderly series of changes occurring in plant communities over a given period of time, until a stable/climax community is established. It usually commences in a newly formed open/barren habitat/abandoned farmland, which is usually as a result of human activities/natural disasters/ catastrophes. The pioneer/primary colonizers have short life cycles/span, which get replaced by other plants which thus derive nutrients from their remains. These latter secondary colonizers have longer life cycles/span. - The initial pace of a succession is rapid but it gradually slows down until a final/stable/climax community is reached (b) Ways by which Nitrogen is made available to soil include: (1) Through nitrogen fixation (2) Through thunder storms and lightening (3) By putrefaction/decay of organic matter (4) By nitrification (5) By application of artificial fertilizers (6) By application of farmyard manure/organic fertilizers/poultry, droppings/animal dungs/green manure.

(a) Conservation of natural resources is necessary for the following reasons: (1) The wise use/safe-keeping/ management of natural resources, for the benefit of mankind, (2) To ensure their continuous availability/avoid their decline/extinction. (b)(i) The following are the methods of soil conservation: (1) Planting grasses/legumes (2) Crops must be planted on ridges across slopes (3) Practicing shifting cultivation/bush fallowing/crop rotation (4) Avoiding/preventing bush burning (5) Addition of manure/fertilizer to the top soil (6) Spreading a layer of vegetable material on cultivated farmland/mulching (7) Constructing ridges across the slope of the land at intervals/contour ridging (8) Planting trees/reafforestation (9) Prevention of over-grazing (ii) Natural resources that can be conserved are: (1) Water (2) Forest (3) Wildlife (4) Mineral resources (5) Genetic mineral/genes (6) Petroleum/coal/gas/fossil fuel/ iron ore, tin, gold (c) Factors that negatively affect conservation of forest in West Africa include the following: (1) Uncontrolled/over-exploitation of forest trees/indiscriminate felling/lumbering of forest trees (2) Lack of afforestation/tree planting. (3)Bush burning/wild fires (4) Non enforcement of conservation laws (5) Lack of /no knowledge of conservation education/awareness (6) Use of firewood/charcoal for fuel (7) Air/soil pollution. (d) Denitrification stage of the nitrogen cycle: - Denitrifying bacteria/certain fungi in the soil Convert nitrates into nitrites Some bacteria/pseudomonas spp can convert ammonia/nitrite/nitrate into gaseous nitrogen, which is released into the atmosphere, leading to reduction of soil nitrogen content, resulting in reduced soil fertility

(a) A hormone can be defined as a chemical substance produced in small quantities by endocrine/ductless glands and carried to all other parts of the body/target organs by blood stream/vascular system, where it produces/exerts a response. (b) Role of adrenaline in an emergency: - Any emergency experienced by an animal usually causes a sudden rage/fear/fright This leads to the release of adrenalin into the blood; which stimulates the sympathetic nervous system and consequently many different organs The rate of heart beat is increased and there is heavy breathing Similarly, there is increase in the body blood sugar/conversion of liver glycogen into glucose. The muscular tone/power is increased/ there is resistance to fatigue, the pupils of the eyes dilate and the visceral muscles are affected, the animal reacts quickly and energetically. (c) Differences between hormonal co-ordination and nervous co-ordination Hormonal co-ordination Nervous co-ordination Involves transmission of chemicals Involves transmission of electrical impulses and chemical substances by the nervous system Response to stimulus is slower Response to stimulus is faster Hormones are secreted into the blood and carried to any part of the body Nerve impulses are transmitted to a particular location/target organ by a particular set of neurons The target is usually far away from the site of production Target organ maybe near or far Response may last for a long time Response are short lived secretion of hormones and their actions are involuntary nervous actions and their responses are voluntary and involuntarily Hormonal co-ordination occurs in both plants and animals Nervous co-ordination occurs only in animals (d)(1) Animal Hormones: - Somatotropic hormone Prolactin Gonatotropic Thyroxine Thyrotropic hormone Oxytocine Anti-diuretic hormone/A.D.H. Parafhormone Adrenalin Insulin Oestrogen Progesterone Testosterone And rosterone (ii) Plant Hormones: - 1 AA/indole-3- Acetic acid/Auxin 2-4D/2-4 Dichlorophenoxy acetic acid Gibberellins Cydtokinins/kinins Abscisie/Absisic acid Benzoic acid NAA/Naphthalene acetic acid IBA/Indolebutryric acid Ethelene Vernalin.

(a)(1) Respiration: This is a process in living organisms cells involving enzyme-catalyzed chemical reactions; in which food substances/glucose are broken down within cells, to release energy, in the presence or absence of oxygen. (ii) Aerobic respiration;- C\(_6\)H\(_1\)\(_2\)O\(_6\)+6O\(_2\) →6H\(_2\)O + 6CO\(_2\) + Energy Anaerobic respiration: C\(_6\)H\(_1\)\(_2\)O\(_6\)→​​​​​​​2C\(_2\)H\(_5\)OH+2CO\(_\)2 + Energy (b)(i) During Inhalation: (1) External intercostal muscles contract (2) Internal intercostal muscles relax (3) Ribs move up and outwards (4) Diaphragm contracts/flattens (5) Volume of thorax cavity increases (6)Air pressure decreases (7)Air rushes into the lungs from the atmosphere. (ii) During Exhalation: - External intercostal muscles relax - Internal intercostal muscles contract - Ribs move down and inwards - Diaphragm relaxes/becomes dome-shaped -Volume of thorax cavity decreases -Air pressure increases - Air is forced out of lungs into the atmosphere.

If 13m + 24m = 41m 1 * m1 + 3 0 + 2 * m1 + 4 * m0 = 4 * m1 + 1 * m0 1 * m + 3 * 1 + 2 * m + 4 * 1 = 4 * m + 1 * 1 m + 3 + 2m + 4 = 4m + 1 3m + 7 = 4m + 1 4m -3m = 7 - 1 m = 6

\(\frac{321_4}{23_4}\) = \(\frac{(3\times4^{2})+(2\times4^{1})+(1\times4^{0})}{(2\times4^{0})+(3\times4^{0})}\) = \(\frac{3\times16+2\times4+1\times1}{2\times4+3\times1}\) = \(\frac{48+8+1}{8+3}\) =\(\frac{57}{11}\) = 5\(\hspace{1mm}remainder\hspace{1mm}2\) ∴ r = 2\(_{10}\) Now\(\hspace{1mm}convert\hspace{1mm}2_{10} \hspace{1mm}to\hspace{1mm}base\hspace{1mm}4\frac{4}{2}\) = 2\(\frac{4}{0}\) = 0\(\hspace{1mm}or\hspace{1mm}2\) ∴ r = 2

3\(\frac{1}{2}\) - (2\(\frac{1}{3}\) x 1\(\frac{1}{4}\)) + \(\frac{3}{5}\)) = \(\frac{7}{2}\) - (\(\frac{7}{3}\) x \(\frac{5}{4}\)) + \(\frac{3}{5}\)) = \(\frac{7}{2}\) - \(\frac{35}{12}\) + \(\frac{3}{5}\) = L.C.M = 60 = \(\frac{(210 - 175 + 36)}{60}\) = \(\frac{71}{60}\) = 1\(\frac{11}{60}\)

To find the interest on \( N250.00 \) for \( 6 \) months at the same rate, we follow these steps: Calculate the Interest Rate Given: P = N150.00, T = 2\(\frac{1}{2}\) years and I = N4.50 Using the formula for simple interest: \(I = P \times r \times T\) Rearranging to find the interest rate \( r \): \(r = \frac{I}{P \times T}\) Substituting the values: \(r = \frac{4.50}{150 \times 2.5}\) Calculating \( P \times T \): \(P \times T = 150 \times 2.5 = 375\) Now, substituting back to find \( r \): \(r = \frac{4.50}{375} = 0.012\) Calculate the Interest for N250.00 \) for 6 Months We need to calculate the interest for: P = N250.00, T = 6 months = 0.5yrs, r = 0.012 Using the interest formula again: \(I = P \times r \times T\) Substituting the values: \(I = 250 \times 0.012 \times 0.5\) \(I = 250 \times 0.012 = 3\) Then: \(I = 3 \times 0.5 = 1.50\) The interest on \( N250.00 \) for \( 6 \) months at the same rate is N1.5

Let x = the number of oranges The 1st received 1/3 of x = 1/3x ∴Remainder = x - 1/3x = 2x/3 The 2nd received 2/3 of 2x/3 = 2/3 * 2x/3 = 4x/3 The 3rd received 12 oranges ∴1/3x + 4x/9 + 12 = x (3x + 4x + 108)/9 = x 3x + 4x + 108 = 9x 7x + 108 = 9x 9x - 7x = 108 2x = 108 x = 54 oranges

\(\frac{81^{\frac{3}{4}}-27^{\frac{1}{3}}}{3 \times 2^3}\) = \(\frac{(3^{3-\frac{3}{4}}-3^{3-\frac{3}{4}})}{3\times 2^3}\) = \(\frac{3^3 - 3}{3 \times 8}\) = \(\frac{27-3}{24}\\=\frac{24}{24}\) =1