Question 1: The inverse square law states that the intensity of light or radiation from a point source decreases proportionally to the square of the distance from the source. Explain in your own words why this law is important in understanding photosynthesis in plants.

Answer: Because as light travels away from the source, its intensity diminishes rapidly, affecting the amount of light energy available for photosynthesis.

Question 1: Define the inverse square law as it applies to light intensity.

Answer: It states that the intensity of light decreases proportionally to the inverse of the square of the distance from the source.

Question 2: Describe how light intensity affects the rate of photosynthesis in aquatic plants.

Answer: Higher light intensity generally increases the rate of photosynthesis up to a certain point, as more light energy is available for the process.

Question 1: A lamp with a power of 100 watts emits light uniformly in all directions. Calculate the light intensity (in W/m²) at a distance of 2 meters from the lamp. Use the formula I = P / (4πr²).

Answer: I = 100 / (4 * π * (2)²) = 100 / (4 * π * 4) = 100 / (50.27) ≈ 1.99 W/m²

Question 2: If the light intensity at 3 meters from a source is 1.11 W/m², what is the intensity at 1.5 meters, assuming the inverse square law applies?

Answer: I₂ = I₁ * (r₁/r₂)² = 1.11 * (3/1.5)² = 1.11 * (2)² = 1.11 * 4 = 4.44 W/m²

Question 1: Describe a basic experiment to investigate how light distance affects photosynthesis in aquatic plants. Include variables to control and measure, as well as safety precautions.

Answer: Set up multiple aquatic plant samples at varying distances from a light source. Control variables include water temperature, light wavelength, and plant species. Measure the rate of photosynthesis by oxygen production or starch accumulation. Safety precautions involve handling electrical equipment safely and avoiding water spills.

Question 1: In an experiment, a light source of constant power is placed at distances of 1 m, 2 m, and 4 m from aquatic plants. The measured light intensities are 100 W/m², 25 W/m², and 6.25 W/m² respectively. Analyse the data and explain how it supports the inverse square law.

Answer: The data shows that when the distance doubles from 1 m to 2 m, the intensity decreases to a quarter (from 100 to 25 W/m²). When the distance doubles again from 2 m to 4 m, the intensity reduces to a sixteenth (from 25 to 6.25 W/m²). This pattern supports the inverse square law, which states that light intensity is inversely proportional to the square of the distance.

Question 1: Explain how understanding the inverse square law can help optimise artificial lighting in greenhouses to maximise photosynthesis.

Answer: By adjusting the distance of artificial lights to the plants, growers can ensure optimal light intensity, maximising photosynthesis while conserving energy.

Question 2: Describe a technological application that uses the inverse square law to improve energy efficiency or biological research.

Answer: Photovoltaic panels and LED grow lights are positioned considering the inverse square law to optimise light exposure and energy use in energy-efficient systems and plant research.