Question

self check

1. in order to produce energy, cells start with glycolysis. if oxygen is not present after glycolysis, what process occurs next?

a) electron transport chain b) krebs cycle c) fermentation

1. if oxygen is present after glycolysis, what process occurs next?

a) electron transport chain b) krebs cycle c)fermentation

1. a process that does not require oxygen is known as ______________.
2. in glycolysis, glucose is broken into 2 ________________ molecules.
3. where does the krebs cycle occur? ______________
4. what gas is a waste product produced during the krebs cycle? ______

Explanation:

Question 1

Glycolysis is the first step of cellular respiration. If oxygen is absent after glycolysis, cells undergo fermentation (anaerobic respiration) to produce energy. Electron Transport Chain and Krebs Cycle require oxygen.

When oxygen is present after glycolysis, the Krebs Cycle (Citric Acid Cycle) occurs next, followed by the Electron Transport Chain. Fermentation is anaerobic.

A process that does not require oxygen is called anaerobic. Aerobic processes need oxygen, while anaerobic ones (like fermentation) do not.

Answer:

c) Fermentation

Question 2