Describe the factors that affect the rate of transpiration and explain how they do so. Include how light intensity, temperature, humidity, and wind speed influence transpiration.

Here are the answers to the questions: Question 1: a) The aim of this experiment was to investigate the effect of light intensity on the rate of transpiration. b) • In the dark room, the rate of transpiration would be very low or negligible because stomata would close in the absence of light, reducing water loss. • In the well-lit room, the rate of transpiration would be high because stomata would open in the presence of light, allowing for increased evaporation of water from the leaves. Question 2: Drooping of leaves on a hot sunny day reduces the surface area exposed to direct sunlight, thereby decreasing the rate of transpiration and conserving water. This prevents excessive water loss and wilting. Question 3: Environmental factors affect the rate of transpiration as follows: • Temperature: Higher temperatures increase the kinetic energy of water molecules, leading to a faster rate of evaporation and thus increased transpiration. • Humidity: Lower humidity creates a steeper water potential gradient between the leaf and the atmosphere, increasing the rate of water diffusion out of the stomata and thus increasing transpiration. • Wind speed: Increased wind speed removes water vapor from around the stomata, maintaining a steep water potential gradient and increasing the rate of transpiration. • Light intensity: Higher light intensity causes stomata to open wider to facilitate photosynthesis, leading to an increased rate of transpiration. Question 4: a) A: Xylem B: Phloem Question 5: a) R: Sieve tube element S: Companion cell Cell T: Sieve plate b) The function of the structure labeled S (Companion cell) is to provide metabolic support and energy to the sieve tube elements, which lack a nucleus and many organelles. c) Xylem is considered a mechanical tissue because its vessels have thick, lignified walls that provide structural support and rigidity to the plant, helping it stand upright and resist bending. Question 6: a) The material that strengthens xylem tissue is lignin. b) The tissue that is removed when the bark of a dicotyledonous plant is ringed is the phloem. Question 7: Xylem vessels are adapted for support by having thick, lignified walls which are rigid and prevent the vessels from collapsing, thus providing mechanical strength to the plant. Question 8: The role of vascular bundles in plant nutrition is to transport essential substances. Xylem within the vascular bundles transports water and dissolved mineral salts from the roots to all parts of the plant, while phloem transports manufactured food (sugars) from the leaves to other parts of the plant for growth and storage. Question 9: Two tissues which are thickened with lignin are: • Xylem vessels • Sclerenchyma fibers Question 10: Support in herbaceous plants is primarily attained through turgor pressure. When plant cells absorb water by osmosis, their vacuoles swell and push the cell membrane against the cell wall, making the cells turgid and rigid, which in turn supports the plant. Question 11: a) The section was taken from a dicotyledonous stem. b) Two reasons for this answer are: • The vascular bundles (xylem and phloem) are arranged in a distinct ring. • There is a clearly visible pith in the center of the stem. c) J: Epidermis K: Phloem L: Xylem Question 12: Two functions of the part labeled M (Pith/Cortex) are: • Storage of food (e.g., starch) • Storage of water Question 13: Water moves from the soil to the leaves in a tree through a process involving several steps: 1. Water enters the root hairs from the soil by osmosis due to a lower water potential inside the root cells. 2. It then moves across the root cortex cells, either through the cytoplasm (symplast pathway) or along cell walls (apoplast pathway), until it reaches the xylem vessels in the root. 3. Within the xylem, water is pulled upwards through the stem and into the leaves primarily by transpiration pull. This pull is created by the evaporation of water from the leaves (transpiration), which generates a negative pressure (tension) that draws water up the continuous column of water in the xylem vessels, maintained by cohesion (water molecules sticking to each other) and adhesion (water molecules sticking to xylem walls). 4. In the leaves, water moves from the xylem into the mesophyll cells and evaporates into the air spaces, eventually diffusing out of the stomata into the atmosphere. Question 14: Two ways in which root hairs are adapted to their function are: • They are long and numerous, providing a large surface area for efficient absorption of water and mineral salts. • They have thin cell walls and cell membranes, which reduce the diffusion distance for water and dissolved minerals to enter the cell. Send me the next one 📸