Question 1

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

Accepted Answer

It is the site where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins.

Question 2

A scientist observes a eukaryotic cell engulfing a large bacterium. Which process is most likely occurring, and which organelle will digest the bacterium?

Accepted Answer

Phagocytosis; lysosome

Question 3

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

Accepted Answer

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

Question 4

A mutation causes a plant cell to lack plasmodesmata. Which of the following consequences is most likely?

Accepted Answer

The cell will have reduced ability to transfer small molecules and signals directly to adjacent cells.

Question 5

Which of the following statements about the extracellular matrix (ECM) is correct?

Accepted Answer

The ECM in animal cells is primarily composed of proteins like collagen, while in plant cells it is mainly cellulose.

Question 6

A researcher adds a competitive inhibitor to an enzyme-catalyzed reaction. Which of the following best describes the effect on enzyme activity?

Accepted Answer

The inhibitor binds to the active site, preventing substrate binding, but increasing substrate concentration can overcome inhibition.

Question 7

Which of the following equations correctly represents the relationship between Gibbs free energy, enthalpy, and entropy?

Accepted Answer

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

Question 8

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

Accepted Answer

Electron transport chain and oxidative phosphorylation; inner mitochondrial membrane

Question 9

A 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?

Accepted Answer

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

Question 10

Which of the following best explains why oxygen is essential for aerobic cellular respiration?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, allowing ATP production to continue.

Question 11

Which of the following is a key difference between photosynthesis and aerobic cellular respiration?

Accepted Answer

Photosynthesis is overall endergonic ($$\Delta G \u003e 0$$), while aerobic respiration is exergonic ($$\Delta G \u003c 0).$$

Question 12

A bamboo shark's digestive enzyme activity is measured at different temperatures. The results show a sharp decrease in activity above 40°C. What is the most likely explanation?

Accepted Answer

The enzyme denatures at high temperatures, losing its functional shape.

Question 13

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

Accepted Answer

It catalyzes the fixation of carbon dioxide during the Calvin cycle.

Question 14

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

Accepted Answer

ATP binds to phosphofructokinase, decreasing its activity when ATP levels are high.

Question 15

Which of the following best explains why substrate saturation limits the rate of enzyme-catalyzed reactions?

Accepted Answer

All active sites are occupied, so increasing substrate concentration further does not increase the reaction rate.

Question 16

Which of the following correctly matches a cell-cell connection with its function in animal cells?

Accepted Answer

Gap junctions: allow direct transfer of ions and small molecules between adjacent cells

Question 17

Which of the following best describes the main function of the Golgi apparatus in the endomembrane system?

Accepted Answer

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

Question 18

Which of the following is a correct sequence of events for the signal hypothesis directing a protein into the endomembrane system?

Accepted Answer

Signal sequence emerges from ribosome $$\rightarrow$$ SRP binds signal sequence $$\rightarrow$$ SRP receptor binds SRP $$\rightarrow$$ protein enters ER

Question 19

Which of the following best explains why cells perform fermentation under low oxygen conditions?

Accepted Answer

Fermentation regenerates NAD$$^+$$, allowing glycolysis to continue producing ATP.

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

Guida di studio - Domande di pratica

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