A Level Biology Practice Exam

What is the role of a potometer in plant biology?

1. Measuring chlorophyll concentration

2. Measuring growth rates of stems

3. Measuring transpiration rates

4. Measuring water loss from leaves

The correct answer is: Measuring transpiration rates

The potometer is primarily used to measure transpiration rates in plants. Transpiration is the process by which water is absorbed by roots from the soil, moves through plants, and is released as water vapor through small openings called stomata in the leaves. By using a potometer, researchers can determine the rate at which water is lost from a plant, providing insights into its overall health and efficiency in water use. While water loss from leaves is a related concept, the primary function of the potometer is to quantify the rate of transpiration, which incorporates factors like environmental conditions (such as humidity and temperature) and the plant's water uptake mechanisms. Measuring chlorophyll concentration and growth rates of stems are unrelated functions that do not utilize a potometer's capabilities for gauging water movement and loss in plants.