Question 1

Which of the following best explains why phospholipids form a bilayer in biological membranes?

Accepted Answer

Phospholipids are amphipathic, with hydrophilic heads facing water and hydrophobic tails shielded inside.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which term best describes the solution?

Accepted Answer

Hypotonic

Question 3

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses specific transmembrane proteins to move substances down their concentration gradient.

Question 4

Which equation correctly represents the free energy change ($$\Delta G) of a $$reaction?

Accepted Answer

$$\Delta G = G_{final\ state} - G_{initial\ state}$$

Question 5

Which of the following best describes the function of the sodium-potassium pump in animal cells?

Accepted Answer

It uses ATP to move sodium out of the cell and potassium into the cell, both against their concentration gradients.

Question 6

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will lose water, undergo plasmolysis, and the plasma membrane will pull away from the cell wall.

Question 7

Which of the following is a key difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Carrier proteins undergo conformational changes to move molecules, while channel proteins provide a continuous passage.

Question 8

Which process is responsible for the secretion of insulin from pancreatic cells?

Accepted Answer

Exocytosis

Question 9

During cell signaling, what is the role of a ligand?

Accepted Answer

It is a molecule that specifically binds to a receptor, triggering a cellular response.

Question 10

Which of the following best describes the function of a phosphorylation cascade in cell signaling?

Accepted Answer

It amplifies the signal by activating multiple proteins through sequential phosphorylation.

Question 11

Which of the following is true about the role of ATP in cellular work?

Accepted Answer

ATP hydrolysis releases energy that can be used to drive endergonic reactions.

Question 12

A cell is exposed to a toxin that irreversibly inhibits all protein kinases. Which process would be most directly affected?

Accepted Answer

The ability to amplify signals through phosphorylation cascades.

Question 13

Which of the following best describes the process of cotransport in plant cells?

Accepted Answer

A proton pump uses ATP to create a gradient, and the downhill flow of protons drives the active transport of another molecule such as sucrose.

Question 14

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Absorption of cholesterol by human cells for membrane synthesis.

Question 15

Which of the following statements about the second law of thermodynamics is correct?

Accepted Answer

Every energy transfer or transformation increases the entropy of the universe.

Question 16

Which of the following best describes the difference between exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and release energy, while endergonic reactions have a positive $$\Delta G$$ and require energy input.

Question 17

Which of the following is a function of membrane carbohydrates?

Accepted Answer

They are involved in cell-cell recognition by binding to molecules on the extracellular surface.

Question 18

Which of the following best explains why ions cannot easily cross the lipid bilayer without assistance?

Accepted Answer

Ions are repelled by the hydrophobic interior of the lipid bilayer.

Question 19

Which of the following is a correct sequence of events in the process of exocytosis?

Accepted Answer

Vesicle buds from the Golgi, travels to the plasma membrane, fuses, and releases contents outside the cell.

Membrane Transport and Cell Signaling: Study Notes for General Biology

Guida di studio - Domande di pratica

Study guide - Flashcard