Question

3.3.2 quiz: investigate cycling of o₂ and co₂ a student hypothesizes that the bubbles on this water plant are oxygen gas (o₂). however, identifying a gas as o₂ with direct evidence requires many kinds of equipment. which observation would provide indirect evidence that the bubbles are not o₂? a. a change in the size of the plant’s leaves over time b. a description of the color and shape of the plant’s leaves c. the estimated volume of all bubbles produced by the plant d. the production of bubbles by the plant when it is in darkness

Explanation:

To determine indirect evidence that the bubbles are not \( O_2 \), we analyze photosynthesis (which produces \( O_2 \) in light) and respiration (which produces \( CO_2 \) and can occur in darkness).

• Option A: Leaf size change over time relates to growth, not gas production type.
• Option B: Leaf color/shape description is irrelevant to gas identity.
• Option C: Bubble volume doesn’t indicate gas type.
• Option D: Plants produce \( O_2 \) via photosynthesis (needs light). If bubbles form in darkness, the gas is likely from respiration (not \( O_2 \)), providing indirect evidence.

Answer:

D. The production of bubbles by the plant when it is in darkness