Question

Which of the following properties are common to both respiration and photosynthesis?

A. Oxygen functions as an electron acceptor
B. Energy derived from oxidation of organic molecules
C. Synthesis of ATP from the energy of a proton gradient
D. All of the above

Answer 1

The common property to both respiration and photosynthesis is the synthesis of ATP from the energy of a proton gradient. This occurs through chemiosmotic mechanisms in electron transport chains within chloroplasts and mitochondria respectively.

Step-by-step explanation:

The correct answer to the question is C. Synthesis of ATP from the energy of a proton gradient. This is because both respiration and photosynthesis involve electron transport chains that harness energy to pump hydrogen ions across a membrane, creating an electrochemical gradient. This chemiosmotic gradient across the membrane is then used by ATP synthase to produce ATP. During photosynthesis, this process occurs in the chloroplasts, where energy from sunlight is used to split water molecules and generate a proton gradient. In cellular respiration, a similar process occurs in the mitochondria, where electrons from the oxidation of glucose are used to create a proton gradient.

In contrast, Option A is incorrect because oxygen is not an electron acceptor in photosynthesis; it is actually a byproduct of water splitting. Option B is also incorrect as photosynthesis does not derive energy from the oxidation of organic molecules; instead, it uses light energy to build organic molecules.