DAT - Dental Admission Biology: Cellular Metabolism Questions and Answers 1

Question 1

A scientist is studying a facultative anaerobe. Under which condition would the organism produce the most ATP per molecule of glucose?

Accepted Answer

In the presence of oxygen

Answer

Aerobic respiration, which occurs in the presence of oxygen, yields significantly more ATP than anaerobic pathways like fermentation. The complete oxidation of glucose through glycolysis, the Krebs cycle, and oxidative phosphorylation can produce approximately 32-38 ATP, whereas fermentation produces only a net of 2 ATP from glycolysis.

Question 2

Which of the following correctly pairs a metabolic process with its primary cellular location in eukaryotes?

Accepted Answer

Krebs Cycle - Mitochondrial Matrix

Answer

The Krebs Cycle (also known as the citric acid cycle) occurs in the mitochondrial matrix. Glycolysis takes place in the cytoplasm, the electron transport chain is located on the inner mitochondrial membrane, and fermentation also occurs in the cytoplasm.

Question 3

During strenuous exercise, muscle cells may switch to anaerobic respiration. What is the primary purpose of converting pyruvate to lactate in this process?

Accepted Answer

To regenerate NAD+ from NADH

Answer

The primary purpose of lactic acid fermentation is to regenerate NAD+ from the NADH produced during glycolysis. This allows glycolysis to continue producing a small amount of ATP even in the absence of oxygen, which is required for the electron transport chain to function and regenerate NAD+ aerobically.

Question 4

A patient is found to have a genetic disorder that inactivates the enzyme phosphofructokinase-1 (PFK-1), a key regulatory enzyme in glycolysis. Which of the following metabolic consequences would be expected?

Accepted Answer

Increased rate of gluconeogenesis

Answer

PFK-1 is a key irreversible enzyme in glycolysis. Its inactivation would halt glycolysis, leading to a cellular energy deficit. To compensate and maintain blood glucose levels, the body would upregulate gluconeogenesis, the pathway that synthesizes glucose from non-carbohydrate precursors. The breakdown of glucose would decrease, fructose-1,6-bisphosphate levels would drop (as it's the product of PFK-1), and glucose-6-phosphate would likely accumulate as it cannot proceed down the glycolytic pathway.

Question 5

In photosynthesis, the light-independent reactions (Calvin cycle) utilize which products from the light-dependent reactions?

Accepted Answer

ATP and NADPH

Answer

The light-dependent reactions capture light energy and use it to produce ATP and NADPH. These energy-rich molecules are then used in the light-independent reactions (Calvin cycle) to fix carbon dioxide and synthesize glucose.

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DAT - Dental Admission Biology: Cellular Metabolism Questions and Answers 1