Study the diagrams and answer the questions.

You're on a roll — Here are the answers to the questions: 9. The diagram below represents an organ from a bony fish. Study the diagram and answer the questions. The diagram for question 9 was not visible in the previous image. Based on the visible part of the question, it refers to the organ shown at the top of the first image. a) Name the organ. (1mk) The organ shown is a gill. b) State three ways in which part K is adapted to its function. (3mk) Part K represents the gill filaments. • They have a large surface area due to numerous lamellae, maximizing gas exchange. • They have a rich blood supply (dense capillary network) to maintain a steep concentration gradient for gases. • They have thin walls (one-cell thick epithelium) to provide a short diffusion distance for gases. 10. The diagram below illustrates the structure of Rhizopus (bread mould) a) Name the parts labeled J and M. (2mks) J: Sporangiophore* M: Rhizoids* b) State the function of structure labeled K and M. (2mks) K (Sporangium): Contains and produces spores for asexual reproduction*. M (Rhizoids): Anchor the fungus to the substrate and absorb nutrients*. 11. Explain how sunken stomata lower the rate of transpiration. (2mk) Sunken stomata are located in pits or depressions on the leaf surface. This arrangement traps a layer of humid air around the stomata, increasing the humidity in the immediate vicinity of the stomatal pore. This reduces the water potential gradient between the inside of the leaf and the outside atmosphere, thereby slowing down the rate of water vapor diffusion out of the leaf and lowering transpiration. 12. State three functions of mammalian blood other than transport of substances. (3mk) • Defense against pathogens (due to white blood cells and antibodies). • Regulation of body temperature (by distributing heat throughout the body). • Blood clotting (to prevent excessive blood loss during injury). 13. State three ways in which the ileum is structurally adapted to the absorption of digested food. (3mk) • The inner surface is folded into numerous finger-like projections called villi, which greatly increase the surface area for absorption. • The epithelial cells lining the villi have microscopic folds called microvilli, further increasing the surface area. • Each villus has a rich blood supply (capillary network) and a lacteal, which efficiently transport absorbed nutrients away, maintaining a steep concentration gradient. 14. State how xylem is adapted to its function. (3mks) • Xylem vessels have lignified walls, which provide mechanical support to the plant and prevent the vessels from collapsing under tension. • They form continuous tubes from the roots to the leaves, allowing for an uninterrupted flow of water. • They have no cross-walls and are essentially dead cells, forming a hollow lumen that offers little resistance to water flow. 15. State functional differences between arteries and veins. (2mks) | Feature | Arteries | Veins | | :------ | :------- | :------ | | Direction of blood flow | Carry blood away from the heart | Carry blood towards the heart | | Oxygenation of blood | Carry oxygenated blood (except pulmonary artery) | Carry deoxygenated blood (except pulmonary vein) | 16. What is oxygen debt? (2mk) Oxygen debt is the amount of extra oxygen required by the body after a period of strenuous exercise to oxidize the accumulated lactic acid (produced during anaerobic respiration) into carbon dioxide and water, and to restore ATP and creatine phosphate levels. 17. What is the importance of sebaceous glands in the human skin? (2mks) Sebaceous glands produce and secrete sebum, an oily substance. Sebum lubricates the skin and hair, keeping them soft and pliable. It also has mild antibacterial and antifungal properties, helping to protect the skin from infections, and makes the skin waterproof. 18. a) Name the hormones responsible for the regulation of blood sugar level. (2mk) • Insulin • Glucagon 18. b) Explain the effects of insulin when there is high blood sugar levels. (3mk) When blood sugar levels are high, the pancreas releases insulin. Insulin acts on target cells (like liver and muscle cells) to increase their uptake of glucose from the blood. It also stimulates the liver and muscle cells to convert excess glucose into glycogen for storage (glycogenesis) and promotes the conversion of glucose into fat. These actions collectively lower the blood sugar level back to normal. 19. Define the following terms:(2mks) i) Cephalothorax The cephalothorax is a body region found in some arthropods (like crustaceans and arachnids) where the head and thorax segments are fused together into a single, distinct unit. ii) Eukaryotes Eukaryotes are organisms whose cells contain a membrane-bound nucleus and other membrane-bound organelles (such as mitochondria, chloroplasts, endoplasmic reticulum, etc.). Their genetic material is organized into chromosomes within the nucleus. 20. To estimate the population of grasshoppers in Kogelo village 400 grasshoppers were caught, which were marked and released. After 24 hours 200 grasshoppers were caught out, of which 80 had been marked. a) Suggest the possible instrument that may have been used for capturing the grasshoppers.(1mk) A sweep net. b) Estimate the population size of the grasshoppers in the village. (2mks) Using the capture-recapture (Lincoln-Petersen) method: N = (M × C)/(R) Where: N = Estimated total population size M = Number of individuals initially marked and released = 400 C = Total number of individuals caught in the second sample = 200 R = Number of marked individuals recaptured in the second sample = 80 N = (400 × 200)/(80) N = (80000)/(80) N = 1000 The estimated population size of the grasshoppers is 1000. 21. Explain how the following features assist in adapting xerophytes to their habitat. i) Folded leaves (2mks) Folded leaves (e.g., rolled or grooved leaves) reduce the surface area exposed to direct sunlight and wind. This creates a humid microclimate within the folds, trapping water vapor and thereby reducing the water potential gradient between the leaf and the atmosphere, which significantly lowers the rate of transpiration. ii) Leaves modified to spines (2mks) Leaves modified into spines (e.g., in cacti) drastically reduce the surface area available for transpiration, thus minimizing water loss. Additionally, spines can serve as a defense mechanism against herbivores, preventing them from consuming the water-storing stems. Got more? Send 'em!