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

A molecule of NAD+ is converted to NADH during a metabolic reaction. Which of the following best describes what has happened to NAD+?

Accepted Answer

It has been reduced by gaining electrons

Question 3

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands are anti-parallel, running 5' to 3' and 3' to 5'

Question 4

In prokaryotic cells, which of the following is true regarding the organization of DNA?

Accepted Answer

DNA is circular and not enclosed in a nucleus

Question 5

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

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP, while oxidative phosphorylation uses a proton gradient and ATP synthase

Question 6

A patient is diagnosed with a bacterial infection that uses nitrate ($$NO_3$$^-$$) as its terminal electron acceptor. Which type of respiration is this, and how does the ATP yield compare to aerobic respiration?

Accepted Answer

Anaerobic respiration; ATP yield is lower than with oxygen

Question 7

During DNA replication, which enzyme is responsible for synthesizing the RNA primer required to initiate synthesis?

Accepted Answer

Primase

Question 8

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

The lagging strand is synthesized discontinuously because DNA polymerase can only add nucleotides to the 3' end

Question 9

Which of the following is a correct description of the Calvin cycle in photosynthesis?

Accepted Answer

It requires three turns to produce one molecule of glyceraldehyde-3-phosphate (G3P)

Question 10

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 11

Which of the following statements about the Shine-Dalgarno sequence is correct?

Accepted Answer

It is a sequence in prokaryotic mRNA that aligns the ribosome for translation initiation

Question 12

Which of the following best describes the difference between inducible and repressible operons?

Accepted Answer

Inducible operons require an inducer to be activated, while repressible operons are turned off by a corepressor

Question 13

Which of the following is true regarding the genetic material of viruses?

Accepted Answer

Viruses can have DNA or RNA, which may be single- or double-stranded

Question 14

A prion differs from other infectious agents because:

Accepted Answer

It is a misfolded protein with no nucleic acid

Question 15

Which of the following best describes the process of horizontal gene transfer known as transduction?

Accepted Answer

Transfer of bacterial DNA by a bacteriophage

Question 16

During the light-dependent reactions of photosynthesis in eukaryotes, what is the role of water?

Accepted Answer

It donates electrons to photosystem II, producing $$O_2 as a $$byproduct

Question 17

Which of the following best explains why fermentation produces less ATP than aerobic respiration?

Accepted Answer

Fermentation only uses substrate-level phosphorylation and does not utilize the electron transport chain

Question 18

Which of the following is a function of the large subunit rRNA in the ribosome?

Accepted Answer

It catalyzes peptide bond formation during translation

Question 19

Which of the following best describes the process of semi-conservative DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental and one new strand

Question 20

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

Accepted Answer

It is caused by a prion and there is no standard effective treatment

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

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