In which cell organelle does the Krebs cycle take place? MCQ with Answer and Explanation

In which cell organelle does the Krebs cycle take place?
A. Inner mitochondrial membrane
B. Stroma of chloroplast
C. Mitochondrial matrix
D. Cytoplasm
Answer: Option C
Solution (By JKSSB Mock Tests)
The Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix in eukaryotes. It oxidizes acetyl-CoA to CO₂, producing NADH, FADH₂, and GTP. The inner membrane houses the electron transport chain. Glycolysis occurs in cytoplasm, the Calvin cycle in chloroplast stroma. The matrix contains the necessary soluble enzymes.

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Question #1
The type of root that is modified for food storage, as in carrot and radish, is:
A. Prop root
B. Taproot
C. Adventitious root
D. Fibrous root

Correct Answer: Option B


Explanation:
Carrot and radish are examples of modified taproots where the primary root swells to store food. Prop roots are adventitious (banyan), fibrous roots are fine and branching (grasses), adventitious arise from stems/leaves.

This question belongs to: Science Biology
Question #2
The 10% law of energy transfer in a food chain was proposed by:
A. Charles Elton
B. Eugene Odum
C. Arthur Tansley
D. Raymond Lindeman

Correct Answer: Option D


Explanation:
The 10% law of energy transfer, which states that only about 10% of the energy from one trophic level is transferred to the next, was proposed by Raymond Lindeman in 1942. This law explains why food chains typically have only 3-4 trophic levels; there is simply not enough energy available to support higher levels.

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Question #3
The hormone that stimulates the release of growth hormone from the pituitary is:
A. Dopamine
B. Growth hormone-releasing hormone (GHRH)
C. Somatostatin
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Correct Answer: Option B


Explanation:
GHRH, from the hypothalamus, stimulates the anterior pituitary to secrete growth hormone. Somatostatin inhibits GH release. Dopamine inhibits prolactin.

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