PCAT Biology 2

Question 1

Which organelle is primarily responsible for producing ATP through oxidative phosphorylation?

Accepted Answer

Mitochondria

Answer

Mitochondria generate ATP via oxidative phosphorylation in their inner membrane through the electron transport chain and ATP synthase.

Question 2

During meiosis II, which event separates sister chromatids?

Accepted Answer

Anaphase II

Answer

During Anaphase II, cohesins break down and sister chromatids are pulled to opposite poles of the cell.

Question 3

What type of RNA carries amino acids to the ribosome during translation?

Accepted Answer

tRNA

Answer

Transfer RNA (tRNA) carries specific amino acids and matches them to codons on mRNA via its anticodon loop.

Question 4

The sodium-potassium pump moves ions against their concentration gradient using which energy source?

Accepted Answer

ATP hydrolysis

Answer

The Na⁺/K⁺-ATPase uses ATP hydrolysis to pump 3 Na⁺ out and 2 K⁺ into the cell against their gradients.

Question 5

Which type of mutation results in a premature stop codon?

Accepted Answer

Nonsense mutation

Answer

A nonsense mutation changes an amino acid codon into a stop codon (UAA, UAG, or UGA), prematurely terminating translation.

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