Question

which of these statements is true about autotrophs, but not heterotrophs?
○ they use sugar and oxygen to make carbon dioxide and water.
○ they use chlorophyll and oxygen to make carbon dioxide and water.
○ they use sunlight, water, and carbon dioxide to make sugars.
○ they use sunlight, water, and oxygen to make chlorophyll.

Explanation:

1. Analyze the first option: Both autotrophs (during respiration) and heterotrophs (during respiration) use sugar and oxygen to produce carbon dioxide and water. So this is not unique to autotrophs.
2. Analyze the second option: Chlorophyll is a pigment in autotrophs (like plants) and they do not use chlorophyll and oxygen to make carbon dioxide and water. This statement is incorrect.
3. Analyze the third option: Autotrophs (specifically photoautotrophs like plants) perform photosynthesis where they use sunlight, water, and carbon dioxide to make sugars (glucose). Heterotrophs cannot perform photosynthesis and rely on consuming organic matter. So this process is unique to autotrophs.
4. Analyze the fourth option: Autotrophs do not use sunlight, water, and oxygen to make chlorophyll. Chlorophyll is synthesized through other biochemical processes and the inputs for photosynthesis (which makes sugars) are sunlight, water, and carbon dioxide, not oxygen for making chlorophyll. This statement is incorrect.

Answer:

They use sunlight, water, and carbon dioxide to make sugars.