Question 1

Which of the following best describes the function of the Golgi apparatus in a eukaryotic cell?

Accepted Answer

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 2

A scientist is studying a protein that is synthesized in the cytosol but needs to be secreted from the cell. According to the signal hypothesis, which of the following steps must occur for this protein to enter the endomembrane system?

Accepted Answer

A signal recognition particle (SRP) binds to the signal sequence on the growing polypeptide, pausing translation and directing the ribosome to the rough ER membrane.

Question 3

Which of the following cell-cell connections allows for the direct transfer of ions and small molecules between adjacent animal cells?

Accepted Answer

Gap junctions

Question 4

A plant cell is placed in a solution containing a signaling molecule that cannot cross the plasma membrane. Which type of receptor is most likely to mediate the cell's response to this molecule?

Accepted Answer

A G-protein-coupled receptor embedded in the plasma membrane

Question 5

Which of the following best explains why enzymes are able to increase the rate of biological reactions?

Accepted Answer

They lower the activation energy ($$E_a) $$required for the reaction to proceed.

Question 6

A researcher measures the activity of an enzyme in a bamboo shark at different substrate concentrations and finds that the reaction rate plateaus at high substrate levels. What is the most likely explanation for this observation?

Accepted Answer

The enzyme has become saturated; all active sites are occupied, so increasing substrate further does not increase the rate.

Question 7

Which of the following statements about Gibbs free energy ($$\Delta G) is $$correct?

Accepted Answer

A reaction with $$\Delta G \u003c 0 is $$exergonic and spontaneous.

Question 8

During cellular respiration, which step produces the most ATP, and where does it occur in a eukaryotic cell?

Accepted Answer

Electron transport chain and oxidative phosphorylation in the inner mitochondrial membrane

Question 9

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 10

Why do cells carry out fermentation when oxygen is not available?

Accepted Answer

To regenerate NAD$$^+ so $$glycolysis can continue producing ATP.

Question 11

Which of the following statements correctly compares the extracellular matrix (ECM) of animal and plant cells?

Accepted Answer

Animal ECM contains collagen and proteoglycans, while plant ECM (cell wall) contains cellulose, hemicellulose, and pectin.

Question 12

A mutation prevents the formation of desmosomes in epithelial cells. Which of the following would most likely result from this mutation?

Accepted Answer

Cells would lose mechanical strength and be more easily separated under stress.

Question 13

Which of the following is an example of feedback inhibition in cellular respiration?

Accepted Answer

ATP binds to an allosteric site on phosphofructokinase, decreasing its activity when ATP levels are high.

Question 14

Which of the following best describes the role of chlorophyll in photosynthesis?

Accepted Answer

Chlorophyll captures light energy and transfers excited electrons to the electron transport chain in the thylakoid membrane.

Question 15

Where and when is oxygen produced during photosynthesis?

Accepted Answer

In the thylakoid lumen during the light-dependent reactions

Question 16

Which of the following statements about Rubisco is correct?

Accepted Answer

Rubisco catalyzes the fixation of carbon dioxide in the Calvin cycle, but can also react with oxygen, leading to photorespiration.

Question 17

Which of the following best describes the relationship between photosynthesis and aerobic cellular respiration?

Accepted Answer

Photosynthesis is endergonic, requiring energy input, while cellular respiration is exergonic, releasing energy.

Question 18

A cell is exposed to a competitive inhibitor of an enzyme. Which of the following best describes how this inhibitor affects enzyme activity?

Accepted Answer

It binds to the active site, preventing substrate binding, and its effect can be overcome by increasing substrate concentration.

Question 19

Which of the following is a key difference between phagocytosis and receptor-mediated endocytosis?

Accepted Answer

Phagocytosis involves the uptake of large particles or cells, while receptor-mediated endocytosis involves the selective uptake of specific molecules bound to receptors.

Question 20

Which of the following best explains why coupling an endergonic reaction to an exergonic reaction (such as ATP hydrolysis) is important in cells?

Accepted Answer

It allows the overall $$\Delta G of $$the coupled reactions to become negative, making the process spontaneous.

General Biology: Cell Structure, Cell Communication, Metabolism, Respiration, and Photosynthesis

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