(a) Explain how the leaf of a flowering plant is adapted for photosynthesis. (b) Describe briefly the mode of feeding in tapeworm. (c) Name one mineral element each needed for the proper functioning of : (i) bones (ii) red blood cells (iii) thyroid gland. (d)(i) State three benefits of including roughages in the diet of humans. (ii) State three reasons why proteins are important to humans.
Explanation
(a) Adaptation of leaf for photosynthesis
Broad/flat leaf lamella, exposes large surface area for maximum absorption of light Palisade mesophyll cells contain a lot of chloroplast chlorophyll; for maximum absorption of light Position of leaf to stem; for optimum reception of light rays/sunlight Thin lamella; allows light penetration into leaf tissue of mesophyll Palisade cells are at right angle/perpendicular to the upper epidermis/chloroplasts are arranged in the periphery of the cells; all for easy activation of the chloroplasts for photosynthesis Large vacuoles of the palisade cells; store photosynthetic products Large intracellular air spaces in the spongy mesophyll; allow oxygen/carbondioxide to diffuse in/out of the chlorophyllus cells/ gaseous exchange The epidermal cells have thin cell walls; for easy penetration of sunlight to the mesophyll Guard cells have chloroplast; for the absorption of sunlight The bean-shaped structure of the guard cell; is to allow for gaseous exchange The stomata; open easily when it becomes turgid for diffusion of gases/carbon dioxide/oxygen Xylem; conducts water into the leaves for photosynthesis Phloem; transports manufactured food to other parts of the plant.
(b) Mode of feeding of tapeworm; Parasitic mode of feeding; lives in the gut of man/pigs; has hooks/suckers; which enable it attach itself to the lining of the intestine of the host; has a flattened tape-like/ribbon-like body; provide large surface area for easy absorption of digested food; no alimentary/digestive system. (c) Mineral elements necessary for the proper functioning of; (i) Bones - Calcium; phosphorus; fluorine (ii) Red blood cells - Iron; copper (iii) Thyroid gland - Iodine. (d) (i) Benefits of including roughages in the diet of humans :
Stimulates bowel movement/peristalsis Reduces blood cholesterol/bowel cancer/gall stones/appendicitis/ obesity / diabetes mellitus They do not contribute to weight gain/high blood sugar It releases glucose slowly It prevents constipation.
(ii) Importance of proteins to humans;
For the repair of damaged tissues; replacement of worn-out tissues For body building For growth For the supply of the necessary amino acids For formation of hormones/enzymes/antibodies/ forming fibrinogen necessary for blood clotting.
