Question

A research group has discovered an organism with cells that contain a previously undescribed organelle. They do some tests on the isolated organelle to see if it is involved in any major metabolic reactions. To do this, they incubate these organelles for a period of time and determine changes in the amount of various substances in the suspending solution. The results follow.

Glucose: None
CO2: Increase
O2: None
ATP: Increase
NADH: Increase


Based on this analysis, which part of cellular respiration do you conclude is taking place in this organelle?

A) pyruvate oxidation
B) citric acid cycle
C) glycolysis
D) electron transport chain/oxidative phosphorylation
E) glycolysis and the citric acid cycle

Answer 1

B) citric acid cycle

Step-by-step explanation:

Citric acid cycle or Krebs cycle is a part of cellular respiration and occurs in mitochondria in eukaryotes. In this process oxidation of acetyl-coA ( which comes from carbohydrates, fats and proteins) takes place and energy is released.

Along with acetyl-coA, water is also used and in the end NAD+ is reduced to NADH, ATP is produced and by product CO2 is generated. ATP is used as a source of energy. NADH also enters electron transport chain in next stage for production of more ATP.