What is the purpose of a potometer in plant studies?

The purpose of a potometer in plant studies is to measure the rate of transpiration. Transpiration is the process by which plants lose water vapor from their aerial parts, primarily through the stomata in their leaves. A potometer allows researchers to quantify this water loss by measuring the amount of water that is taken up by the plant over a specific period. As the plant transpires, it creates a negative pressure that draws water from the potometer's reservoir, which can be monitored to determine the transpiration rate.

Measuring transpiration is important as it provides insights into plant water use efficiency, environmental factors affecting water loss, and overall plant health, making the potometer a valuable tool in botanical research. The other options do not align with the primary function of a potometer: measuring the rate of photosynthesis involves different assessments, determining soil moisture levels requires different tools, and analyzing nutrient absorption typically involves other methods or equipment.