Question 1: Define the term 'limiting factor' in the context of photosynthesis.

Answer: A limiting factor is an environmental condition that restricts the rate of photosynthesis when it is in short supply or not optimal.

Question 2: List the three main factors that can limit the rate of photosynthesis.

Answer: Light intensity, carbon dioxide concentration, and temperature.

Question 3: Explain how light intensity can limit photosynthesis.

Answer: If light intensity is too low, the energy available for the light-dependent reactions decreases, reducing the overall rate of photosynthesis.

Question 4: Describe the effect of high temperature on the enzymes involved in photosynthesis.

Answer: High temperatures can denature enzymes, reducing their activity and thus decreasing the rate of photosynthesis.

Question 1: If a plant's rate of photosynthesis is 15 μmol CO₂/m²/sec at a light intensity of 600 lux, and the rate drops to 8 μmol CO₂/m²/sec at 300 lux, calculate the percentage decrease in the rate of photosynthesis.

Answer: Percentage decrease = [(15 - 8) / 15] x 100 = 46.67%

Question 2: A plant absorbs 400 ppm CO₂ in the air under normal conditions. During an experiment, the CO₂ concentration is increased to 800 ppm, and the photosynthesis rate increases from 10 μmol to 18 μmol CO₂/m²/sec. Calculate the ratio of the new rate to the original rate.

Answer: Ratio = 18 / 10 = 1.8

Question 1: Describe an experimental setup to test the effect of light intensity on the rate of photosynthesis in aquatic plants. Include variables to control and safety precautions.

Answer: An experiment could involve placing aquatic plants in water under different light intensities using adjustable lamps. The independent variable is light intensity; the dependent variable is the rate of photosynthesis (e.g., oxygen bubbles produced). Control variables include temperature, CO₂ levels, and water quality. Safety precautions include avoiding direct eye exposure to bright light and handling electrical equipment carefully.

Question 2: Identify two environmental conditions that could become limiting factors in a greenhouse and suggest methods to optimize them.

Answer: Light levels can be increased with supplemental lighting, and temperature can be controlled with heating or cooling systems to optimize photosynthesis.

Question 1: Scenario: A plant shows a high rate of photosynthesis in bright light and high CO₂ but a sudden decrease at higher temperatures. What is likely the limiting factor at high temperature?

Answer: Temperature is likely the limiting factor because high heat can denature enzymes involved in photosynthesis.

Question 2: Data: When CO₂ concentration is increased from 300 ppm to 600 ppm, the rate of photosynthesis increases from 12 μmol to 16 μmol CO₂/m²/sec at constant light and temperature. What does this suggest about the limiting factor?

Answer: It suggests that CO₂ was a limiting factor since increasing its concentration increased the rate of photosynthesis.

Question 1: Explain how understanding limiting factors can help improve crop yields in agriculture.

Answer: By optimizing environmental conditions such as light, CO₂, and temperature, farmers can maximize photosynthesis efficiency and increase crop yields.

Question 2: Describe how artificial lighting in greenhouses can be used to overcome limiting factors and enhance plant growth.

Answer: Artificial lighting can supplement natural light, especially during cloudy days or winter, ensuring plants receive adequate light for photosynthesis. Proper control of light intensity and duration can prevent limiting effects and promote healthier, faster-growing plants.