Question 1

Which of the following statements best explains why mitochondria are considered evidence for the endosymbiotic theory of eukaryotic evolution?

Accepted Answer

Mitochondria contain their own circular DNA and ribosomes similar to those found in prokaryotes.

Question 2

During which phase of the eukaryotic cell cycle is DNA replicated, and what is the significance of this phase for genetic inheritance?

Accepted Answer

S phase; it creates identical sister chromatids, ensuring accurate genetic inheritance.

Question 3

A scientist performs a pulse-chase experiment using radioactive amino acids. After a short pulse, most radioactivity is found in the rough ER. After a longer chase, it is found in the Golgi apparatus and then in vesicles. What does this experiment demonstrate?

Accepted Answer

Proteins are synthesized in the cytoplasm, then transported to the rough ER, modified in the Golgi, and finally packaged into vesicles for export.

Question 4

Which of the following best describes the role of the signal recognition particle (SRP) during protein synthesis in eukaryotic cells?

Accepted Answer

SRP binds to the ER signal sequence, halts translation, and directs the ribosome to the rough ER where translation resumes.

Question 5

Which checkpoint in the eukaryotic cell cycle ensures that all chromosomes are properly attached to the mitotic spindle before proceeding to anaphase?

Accepted Answer

Late metaphase (spindle) checkpoint

Question 6

A mutation in the p53 gene would most likely result in which of the following cellular outcomes?

Accepted Answer

Uncontrolled cell division due to failure to halt the cell cycle in response to DNA damage

Question 7

Which of the following equations correctly represents the relationship between free energy, enthalpy, and entropy in a chemical reaction?

Accepted Answer

$$\Delta G = \Delta H - T \Delta S$$

Question 8

Which of the following best explains why enzymes increase the rate of chemical reactions?

Accepted Answer

They lower the activation energy required for the reaction to proceed.

Question 9

A competitive inhibitor of an enzyme acts by:

Accepted Answer

Binding to the active site, preventing the substrate from binding.

Question 10

Which of the following statements about glycolysis is correct?

Accepted Answer

Glycolysis produces a net gain of 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose molecule.

Question 11

During the citric acid cycle, which molecule is regenerated to allow the cycle to continue, and what is the main purpose of this cycle?

Accepted Answer

Oxaloacetate; to oxidize acetyl-CoA and generate NADH and FADH2 for the electron transport chain

Question 12

Which of the following best describes the role of oxygen in aerobic cellular respiration?

Accepted Answer

Oxygen is the final electron acceptor in the electron transport chain, forming water.

Question 13

Which of the following is a key difference between prokaryotic and eukaryotic ribosomes?

Accepted Answer

Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.

Question 14

Which process is responsible for the net production of ATP during the electron transport chain and oxidative phosphorylation?

Accepted Answer

Chemiosmosis via ATP synthase

Question 15

A cell is exposed to a noncompetitive inhibitor. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor binds to an allosteric site, causing a conformational change that reduces enzyme activity.

Question 16

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway acts as an allosteric inhibitor of an early enzyme in the pathway.

Question 17

Which of the following is true regarding the difference between catabolic and anabolic pathways?

Accepted Answer

Catabolic pathways release energy by breaking down molecules; anabolic pathways consume energy to build complex molecules.

Question 18

Which of the following best explains why lactic acid fermentation occurs in human muscle cells during intense exercise?

Accepted Answer

Oxygen is limited, so pyruvate acts as an electron acceptor to regenerate NAD+ for glycolysis.

Question 19

Which of the following is a function of the cytoskeleton in eukaryotic cells?

Accepted Answer

Providing structural support, facilitating cell movement, and organizing organelles

General Biology: Cell Structure, Cell Division, and Metabolism Study Notes

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