Question

check for understanding iii - photosynthesis
plant science basics: plant processes
1 of 5
which of the following is not a characteristic of light-independent reactions?
performed when sunlight is present
also known as carbon-fixing reactions
form sugar molecules from water and carbon dioxide
begin in the stroma of chloroplast

Explanation:

To solve this, we analyze each option:

• Light - independent reactions (Calvin cycle) don't directly require sunlight. They can occur in the presence of sunlight but don't depend on it for energy (they use ATP and NADPH from light - dependent reactions).
• Light - independent reactions are carbon - fixing as they convert \(CO_2\) into sugars, so "Also known as carbon - fixing reactions" is a characteristic.
• They do form sugar from \(CO_2\) (and use energy from ATP/NADPH), so "Form sugar molecules from water and carbon dioxide" (though water is used in light - dependent, the end product of Calvin cycle uses \(CO_2\) and energy to make sugars) is a characteristic.
• Light - independent reactions start in the stroma of chloroplasts, so "Begin in the stroma of chloroplast" is a characteristic.

So the option that is NOT a characteristic is "Performed when sunlight is present" as a defining characteristic of light - independent reactions is that they are not dependent on direct sunlight (even though they can occur when sunlight is present, it's not a requirement like it is for light - dependent reactions).

Answer:

A. Performed when sunlight is present (assuming the first option is labeled A, if not, the option "Performed when sunlight is present")