14. Explain how the xylem are adapted to their function. Xylem vessels are hollow, continuous tubes with lignified walls to transport water and minerals efficiently and provide structural support. 15. In what ways are the gill filaments of fish adapted to their function? • Gill filaments have a large surface area due to numerous folds and lamellae for efficient gas exchange. • They have thin walls (one cell thick) to provide a short diffusion distance for gases. • They possess a rich blood supply to maintain a steep concentration gradient for oxygen and carbon dioxide. 16. Explain how temperature increase the rate of photosynthesis. An increase in temperature, up to an optimum, increases the kinetic energy of enzyme molecules and substrate molecules. This leads to more frequent and energetic collisions between them, increasing the rate of enzyme-catalyzed reactions in photosynthesis. 17.a) Name the only epidermal cell in plants that contain chloroplast. Guard cells 17.b) State one structural difference between palisade cells and spongy mesophyll cells. Palisade cells are elongated and tightly packed, while spongy mesophyll cells are irregularly shaped with large air spaces between them. 18. a) Name the causative agents of the following diseases. i) Amoebic dysentery Entamoeba histolytica ii) Tuberculosis Mycobacterium tuberculosis