Question 1

During cellular respiration, which stage is responsible for the majority of ATP production, and by what mechanism is this ATP generated?

Accepted Answer

Electron Transport Chain via oxidative phosphorylation

Question 2

Which of the following statements correctly describes the difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP from a phosphorylated intermediate, while oxidative phosphorylation uses a proton gradient generated by the electron transport chain to drive ATP synthesis.

Question 3

A molecule of NAD$$^+ is $$converted to NADH during glycolysis. Which of the following best describes this process?

Accepted Answer

NAD$$^+ is $$reduced by gaining electrons.

Question 4

In aerobic respiration, what is the terminal electron acceptor, and how does this affect the total ATP yield compared to anaerobic respiration?

Accepted Answer

Oxygen; it allows for the maximum ATP yield, typically about $$36 to$$ $$38$$ ATP per glucose.

Question 5

Which of the following best explains why fermentation is necessary in some cells under anaerobic conditions?

Accepted Answer

Fermentation allows glycolysis to continue by regenerating NAD$$^+$$ from NADH.

Question 6

During the light-dependent reactions of photosynthesis in eukaryotes, where do these reactions occur and what is the primary purpose of water in this process?

Accepted Answer

In the thylakoid membrane; water donates electrons to Photosystem II.

Question 7

How many turns of the Calvin cycle are required to produce enough G3P to synthesize one molecule of glucose?

Accepted Answer

Six turns

Question 8

Which of the following bonds holds the two DNA strands together in the double helix?

Accepted Answer

Hydrogen bonds

Question 9

What is the function of DNA polymerase III during DNA replication in prokaryotes?

Accepted Answer

It adds nucleotides to the growing DNA strand in the 5' to 3' direction.

Question 10

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments.

Question 11

Which of the following statements about transcription in prokaryotes is correct?

Accepted Answer

Transcription is initiated at the promoter region and proceeds in the 5' to 3' direction.

Question 12

A point mutation that changes a codon from UAU (tyrosine) to UAA (stop) is best described as which type of mutation?

Accepted Answer

Nonsense mutation

Question 13

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

Accepted Answer

Eukaryotic DNA is linear and associated with histones, while prokaryotic DNA is typically circular and not associated with histones.

Question 14

Which of the following best describes a plasmid?

Accepted Answer

A small, circular DNA molecule found in prokaryotes that often carries non-essential genes such as antibiotic resistance.

Question 15

Which of the following is true regarding the Shine-Dalgarno sequence?

Accepted Answer

It is a ribosomal binding site in prokaryotic mRNA that helps align the ribosome with the start codon.

Question 16

Which of the following best describes a repressible operon?

Accepted Answer

It is usually on but can be turned off when a corepressor is present.

Question 17

Which of the following is a characteristic unique to prions compared to other pathogens?

Accepted Answer

They are infectious proteins that lack nucleic acids.

Question 18

A patient is diagnosed with Creutzfeldt-Jakob disease. Which of the following statements about treatment and destruction of the causative agent is correct?

Accepted Answer

There is no effective treatment, and prions require incineration or treatment with strong chemicals such as sodium hydroxide for destruction.

Question 19

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle involves integration of the phage genome as a prophage and can remain dormant.

Question 20

Which of the following is a method of horizontal gene transfer in prokaryotes that involves the uptake of naked DNA from the environment?

Accepted Answer

Transformation

MCB 2010 Exam Two Study Guide – Step-by-Step Guidance

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