Question 1: Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released into the atmosphere. This process helps in cooling the plant and supporting the upward movement of nutrients. Explain briefly why transpiration is essential for plants.

Answer: Transpiration is essential because it helps in cooling the plant, transports nutrients from the soil, and maintains water movement within the plant.

Question 1: Define transpiration.

Answer: Transpiration is the loss of water vapor from parts of plants, mainly through the stomata of leaves.

Question 2: Name the small openings on the underside of leaves through which transpiration occurs.

Answer: Stomata

Question 3: List three environmental factors that influence the rate of transpiration.

Answer: Temperature, humidity, wind speed, light intensity, and soil moisture.

Question 1: If a plant loses 600 grams of water over 10 hours, calculate the transpiration rate in grams per hour.

Answer: Transpiration rate = Total water lost / Time = 600 g / 10 hr = 60 g/hr

Question 2: A leaf has 150 stomata, and during transpiration, 75% of these stomata are open at any given time. If the total rate of water vapor loss is 45 mg per minute, what is the average water vapor loss per open stoma per minute?

Answer: Total open stomata = 150 × 0.75 = 112.5 ≈ 113 Water loss per stoma = 45 mg / 113 ≈ 0.398 mg per minute

Question 1: Describe a simple experiment to test the effect of humidity on the rate of transpiration in a plant.

Answer: Place identical potted plants in environments with different humidity levels (e.g., one in a humid room, one in a dry room). Measure the amount of water lost over a fixed period. Control variables include temperature, light, and soil type. The variable tested is humidity. Record and compare water loss to determine the effect of humidity on transpiration.

Question 2: Identify the independent and dependent variables in the experiment described above.

Answer: Independent variable: Humidity level; Dependent variable: Rate of water loss (transpiration)

Question 3: List two safety precautions to consider when conducting experiments involving plants and water loss measurement.

Answer: Ensure the plants are not exposed to extreme temperatures; handle water and plant materials carefully to avoid spills and contamination.

Question 1: A study shows that in a hot, dry environment, a plant’s transpiration rate increased by 50%, whereas in a shaded, humid environment, it decreased by 30%. Explain why these changes occur based on environmental factors.

Answer: In hot, dry conditions, increased temperature and low humidity cause the stomata to remain open longer or wider, increasing water vapor loss. Conversely, in shaded, humid environments, high humidity reduces the water vapor gradient, leading to decreased transpiration. These environmental factors directly influence the rate at which water is lost through transpiration.

Question 1: How does understanding transpiration help in developing drought-resistant crops?

Answer: By understanding transpiration, scientists can develop crops with modified stomatal behavior or traits that reduce water loss, making them more resistant to drought conditions.

Question 2: Describe one technology or method used in agriculture to manage transpiration and conserve water.

Answer: Use of anti-transpirant sprays that temporarily close stomata, or implementing drip irrigation systems to reduce water loss and improve water use efficiency.