Question

students are studying the rate of yeast fermentation under different conditions. based on the results, which statement is not correct? a fermentation only occurs when sugar is present. b boiling yeast produces oxygen, preventing fermentation. c fermentation is slower when sucrose is used in place of glucose. d the yeast and water did not produce any carbon dioxide bubbles because without a food source, fermentation cannot happen. bar graph with categories: yeast + glucose, yeast + sucrose, boiled yeast + glucose, boiled yeast + sucrose, yeast + water; y - axis labeled number with 0, 10, 20

Explanation:

• Option A: The bar graph shows fermentation (bubble production) occurs with glucose and sucrose (sugars), so fermentation needs sugar, making A correct.
• Option B: Boiling yeast kills it (denatures enzymes), not that it produces oxygen. Fermentation is anaerobic, and boiling stops yeast activity, so B's reasoning is wrong.
• Option C: The height of yeast + glucose bar is slightly higher than yeast + sucrose, suggesting fermentation is a bit faster with glucose, so C (slower with sucrose) is correct.
• Option D: Yeast + water has no bar (no bubbles), as fermentation needs a food source (sugar), so D is correct.

Answer:

B. Boiling yeast produces oxygen, preventing fermentation.