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Commensalism is the association between 2 organisms living together in which only one benefits from the association while the other is neither benefited nor harmed e.g Ramora fish and shark. Commensalism is an example of symbiotic Association.

Thoracic cavity assists in breathing alongside the ribs because it is found in the chest region.

Southern Guinea Savanna is the largest of all biotic community in Nigeria found in Oyo, Osun, Ekiti Status etc.

In an ecosystem the organism which changes light energy into stored chemical energy is the producer.

In the theory of use and disuse by Lamarck Jean he did not propose that there is natural selection of offspring.

During the process of growth the cell does not reduce, it divides, enlarges and differentiates.

Vestigial organs are remaining parts of one's functioning organ e.g appendix in human which function as caecum in herbivore which are minute and are incomplete organs with no special function.

Synecology involves the inter-relationship between groups of organism or species of organisms living together in an area.

One of the process in which nutrient is fixed into the soil is electrical discharge which helps to add nutrient and nitrate to the soil.

a. (i) Challenges that make the conservation of resources difficult: - Limited land area for development leads to the rapid destruction of the natural forest; - Over grazing/over fishing; - Poaching/ killing of endangered species; - Bush burning/poor farming methods; - Over cultivation of land; - High demand for timber that has resulted in the felling of trees/indiscriminate cutting of trees for firewood; - Damming of rivers for hydro-electricity and irrigation has resulted in the alteration of the ecosystem; - Lack of awareness of the populace and policy makers of the need for conservation/lack of education; - Improper enforcement of existing laws/poor leadership; - Forest fire; - Inadequate funding in conservation; - Lack of international/local cooperation on conservation; - Illegal/unlawful exploitation of minerals. (ii) Ways by which Government ensures the conservation of resources: - Creation of parks/gardens/wildlife/zoo/reserves; - Putting in place a chemical and toxic waste dump programmes to avoid water pollution; - Enactment of conservation laws; - Enforcement of conservation laws; - Creating awareness/education through the media; - Establishment of conservation fund; - Training of conservation personnel/employing experts to manage natural resources; - Establishing local and international cooperation; - Aforestation/planting of trees. b. Endangered species - Species whose population has become so small; that it can completely be wiped out/become extinct; if not properly managed. c. (i) Genotype of child: OO (ii) Genotype of Father: OO; AO; BO; d. Importance of genetic variation to plants - It enables plants to spread to colonies/new areas; - It may enable plants to survive harsh/adverse conditions/environments; - It may enable plants to be resistant to diseases; - It gives rise to varieties of desirable plant species; - It makes plants produce better fruits/yield; - It makes plants produce early yield;

a. (i) Type of genetic cross: Dihybrid (ii) Reason for answer: Two characters are involved in the cross/involves two characters separable in inheritance. b. (i) Phenotype of F1: Tall and Red. (ii) Genetic Diagram Let T represent the gene for Tallness; t represent the gene for Dwarfism; R represent the gene for Red; r represent the gene for White. OR Parental genotype TtRr X TtRr X TR Tr tR tr TR TTRR Tall Red TTRr Tall Red TtRR Tall Red TtRr Tall Red Tr TTRr Tall Red TTrr Tall White TtRr Tall Red Ttrr Tall White tR TtRR Tall Red TtRr Tall Red ttRR Dwarf Red ttRr Dwarf Red tr TtRr Tall Red Ttrr Tall White ttRR Dwarf Red ttrr Dwarf White Crosses of parental genotypes Tall and Red - 9 Tall and White - 3 Dwarf and Red - 3 Dwarf and White - 1 Parental genotype Parental gametes (TR, Tr, tR, tr) shown Correct Crosses of parental gamete Phenotypic ratio 9:3:3:1 (iii) Calculation of Tall and White flowers in F2 (3/16) x (160/1) = 30

a. (i) Table Organism Respiratory Tadpole (2 days old) Gill (External) Cockroach Trachea/tracheoles Domestic fowl Lung/lungs Talinum Stoma/stomata Earthworm (moist) Skin surface/body surface Amoeba Cell membrane/plasmalemma/body surface (ii) Characteristic Features of respiratory surfaces - Large surface area; - Thin-walled/thin body surface; - Moist surface; - Well-ventilated surface; - Permeable surface; - Highly vascularised/network of capillaries present. b. Diagram of respiratory organ/gill of Tilapia

No expanded working has been attached for this question yet. The verified answer is Option .

a. Vertebrae with corresponding location Vertebrae Location Cervical Neck Thoracic Chest/Thorax Lumbar Abdomen/Upper abdomen/loin Sacral Hip/lower abdomen Caudal Tail/coccyx b. Function of: (i) Palisade - Manufactures food/carries out photosynthesis/site of photosynthesis; - Contains chloroplasts for photosynthesis; (ii) Vascular bundle - Contains xylem for transport of water/mineral salts/phloem for translocation of manufactured organic substances/hormones; - Provides mechanical support; (iii) Epidermis - It keeps the leaf’s shape; - Provides mechanical support; c. Function of (i) Sieve tube - Translocates/transports manufactured foods to other parts of the plant (ii) Cortex - The cells of cortex store starch; - Outer cortex cells of green stems contain chloroplasts and make food by photosynthesis/chlorophyllus cortex cells manufacture food; (iii) Epidermis - Cells of pith act as packing/food storage tissues; - Supports the stem; d. Structural differences (i) External structural differences between stem and root of a maize seedling Stem of a maize seedling Root of a maize seedling Fibrous root absent fibrous root present Chlorophyllus/greenish non chlorophyllus/non-greenish Leaves are present leaves are absent Thicker in size thinner in size Coleoptiles/shoot sheath present coleoptiles/shoot sheath absent Coleorhizae/radicle sheath absent coleorhizae/radicle sheath present. (ii) Internal structural differences between stem and root of a maize seedling Stem of a maize seedling Root of a maize seedling Vascular bundles are scattered vascular bundles are arranged/in a ring form More vascular bundles less vascular bundles Cortex is narrower cortex is wider Pith is absent pith is present Endodermis absent endodermis present Phloem and xylem do not alternate phloem alternates with xylem Piliferous layer absent piliferous layer present

a. Features of the small intestine that increase the rate of absorption of digested food - Ridges/furrows on inner linings; - Small finger-like projections/villi; - Minute projections/microvilli on the villi; - Thin epithelial lining of the villi; - Highly vascularised/well supplied with blood; - Intestine is long/it has a large surface area. b. Fate of glucose formed in a plant during photosynthesis - Glucose combines with Nitrogen/Sulphur/Phosphorus to form proteins for growth; - Glucose is stored as starch; - Glucose is oxidised to form carbon dioxide/water/energy in respiration; - Glucose is also converted into lipids/cellulose which is stored. c. Mode of feeding of (i) Euglena - Exhibits both autotrophic and heterotrophic modes of nutrition; - In autotrophic mode of feeding, the chlorophyll in its stellate chloroplast absorbs sunlight energy; - And the dissolved carbon dioxide in the pond water diffuses into the cell of Euglena; - Inside the chloroplast, the absorbed solar energy/sunlight is used in the synthesis of glucose from water and carbon dioxide; - Glucose is converted into starch and stored in the paramylum granules; - In heterotrophic mode of feeding, it takes in organic matter/diatoms e.t.c.; - Through the gullet; - And digests it in the reservoir. (i)Spirogyra - Manufactures its own food through photosynthesis; - Its spiral chloroplast/chlorophyll absorbs the sunlight energy; - It absorbs carbon dioxide from water/its environment to manufacture food; - The manufactured food is used; - while the rest/excess is stored in its pyrenoid in the form of starch; d. Characteristics of an Estuarine Habitat - It is shallow; - It has a high level of nutrients; - Salinity/pH/O2 level fluctuates; - Turbidity is high during rainy season; - It is affected by tides; - Species diversity is low; - Muddy/soft soil/substratum d. Differences between an aquatic and terrestrial habitat Aquatic habitat Terrestrial habitat Temperature is lower temperature is higher Water is the medium for growth/reproduction soil is a medium for growth Presence of dissolved oxygen presence of atmospheric oxygen Organisms are not affected by humidity organisms are affected by humidity Organisms are affected by tide/waves/water/current organisms are not affected by tide/waves/water current Organisms are not affected by wind action organisms are affected by wind action Light affects the distribution of organisms more light affects the distribution of organisms less Water is abundant water is not abundant