Final answer:
The claim that light reactions are less important than carbon reactions in photosynthesis is false. Both light reactions and the Calvin cycle are essential for producing the energy and electrons needed for carbohydrate synthesis in plants.
Step-by-step explanation:
The statement that most biologists agree the light reactions are less important than the carbon reactions is false. In photosynthesis, the light reactions and the light-independent reactions, often incorrectly referred to as 'dark reactions', are both crucial for the synthesis of glucose in plants. The term 'dark reactions' can be misleading because it might imply these reactions occur in the absence of light, which is incorrect; the light-independent reactions, or Calvin cycle, do not require direct light but still depend on the products of the light reactions.
The light reactions harness energy from sunlight to produce ATP and NADPH. These energy-carrying molecules are crucial for the Calvin cycle, where carbon fixation takes place. During the fixation stage of the Calvin cycle, carbon dioxide is incorporated into organic molecules, which is later used to produce carbohydrates such as glucose. Therefore, the light reactions provide the energy and electrons necessary for the light-independent reactions.
It is essential to note that the products of the light reactions, ATP and NADPH, have very short lifespans, whereas the carbohydrates produced in the light-independent reactions can be stored for exceedingly long periods, making both stages of photosynthesis significant for the energy economy of the plant.