In a typical aquatic plant photosynthesis lab, which measurement can be used as a proxy to estimate the rate of photosynthesis?

• A. Rate of oxygen production (e.g., volume of $O_2$ released per minute)
• B. Rate of oxygen consumption by mitochondria during cellular respiration
• C. Rate of water uptake by roots as measured by change in plant mass
• D. Rate of ATP breakdown in the cytosol during glycolysis

Answer: (A)

Verified step by step guidance

1. Understand that photosynthesis in aquatic plants produces oxygen as a byproduct when light energy is converted into chemical energy.
2. Recognize that measuring the rate of oxygen production (such as the volume of \( O_2 \) released per minute) directly reflects the photosynthetic activity because oxygen is released during the light-dependent reactions.
3. Consider why other options are less suitable: the rate of oxygen consumption by mitochondria relates to cellular respiration, not photosynthesis; water uptake by roots is not directly linked to photosynthesis rate; ATP breakdown during glycolysis occurs in cellular respiration, not photosynthesis.
4. Conclude that the best proxy measurement for photosynthesis rate in aquatic plants is the rate of oxygen production, as it is a direct and measurable output of the photosynthetic process.
5. To quantify this, set up an experiment to measure the volume of \( O_2 \) gas released over a fixed time period, which can then be used to estimate the photosynthesis rate.