Question 1

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

Accepted Answer

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

Question 2

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

Accepted Answer

Oxygen is the terminal electron acceptor in aerobic respiration, allowing for the maximum ATP yield (about 38 ATP per glucose), whereas anaerobic respiration uses other inorganic molecules, resulting in less ATP production.

Question 3

Which of the following best describes the role of water in the light-dependent reactions of photosynthesis?

Accepted Answer

Water donates electrons to Photosystem II, which are then passed through the electron transport chain, generating ATP and NADPH.

Question 4

A molecule of glucose is metabolized via glycolysis, the Krebs cycle, and the electron transport chain. How many molecules of ATP are produced by substrate-level phosphorylation and by oxidative phosphorylation, respectively, per glucose molecule?

Accepted Answer

Substrate-level phosphorylation: 4 ATP; Oxidative phosphorylation: about 34 ATP

Question 5

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

Accepted Answer

Fermentation does not use an electron transport chain and only generates ATP via glycolysis.

Question 6

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

Accepted Answer

Hydrogen bonds between complementary nitrogenous bases

Question 7

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to the 3’ end?

Accepted Answer

DNA polymerase

Question 8

Which of the following statements about the lagging strand during DNA replication is correct?

Accepted Answer

It is synthesized discontinuously in short fragments called Okazaki fragments.

Question 9

Which of the following best describes a missense mutation?

Accepted Answer

A point mutation that results in a codon change, causing a different amino acid to be incorporated into the protein.

Question 10

Which of the following is true regarding the structure and function of plasmids in prokaryotes?

Accepted Answer

Plasmids are small, circular DNA molecules that often carry genes for antibiotic resistance.

Question 11

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

Accepted Answer

It is a ribosomal binding site in prokaryotic mRNA that helps initiate translation.

Question 12

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

Accepted Answer

Inducible operons are usually off and can be turned on by an inducer, while repressible operons are usually on and can be turned off by a corepressor.

Question 13

A virus contains a genome composed of single-stranded negative-sense RNA. Which enzyme must the virus provide or encode to replicate its genome inside a host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 14

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause neurodegenerative diseases and are resistant to standard sterilization methods.

Question 15

Which of the following is a correct description of the process of horizontal gene transfer by transduction in bacteria?

Accepted Answer

A bacteriophage transfers DNA from one bacterium to another.

Question 16

Which of the following best explains why photorespiration occurs in plants?

Accepted Answer

Photorespiration occurs when the enzyme Rubisco binds $$O_2$$ instead of $$CO_2$$, leading to a wasteful pathway that reduces photosynthetic efficiency.

Question 17

Which of the following is the correct sequence of events in the lytic cycle of a bacteriophage?

Accepted Answer

Attachment, penetration, biosynthesis, maturation, release

Question 18

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

The Calvin cycle produces glyceraldehyde-3-phosphate (G3P) as its direct product, and it takes six turns of the cycle to generate enough G3P to form one glucose molecule.

Question 19

Which of the following best describes the significance of the rRNA in the large subunit of the ribosome?

Accepted Answer

It acts as a ribozyme, catalyzing the formation of peptide bonds during translation.

MCB 2010 Exam Two Study Guide: Microbial Metabolism, Genetics, and Viruses

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