Question 1

Which of the following best explains why membranes with a high proportion of unsaturated fatty acids remain fluid at lower temperatures?

Accepted Answer

Unsaturated fatty acids have bent tails due to double bonds, which prevent tight packing of phospholipids.

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will burst (lyse) because water will move into the cell.

Question 3

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It uses ATP to move 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions into the cell.

Question 4

Which type of membrane transport is illustrated when glucose moves into a cell via a specific carrier protein, without the use of ATP?

Accepted Answer

Facilitated diffusion

Question 5

A plant cell is placed in a hypertonic solution. What will happen to the cell, and what is the term for this process?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 6

Which of the following best describes the role of cholesterol in animal cell membranes at high temperatures?

Accepted Answer

Cholesterol restrains phospholipid movement, decreasing membrane fluidity.

Question 7

Which of the following molecules can most easily cross the plasma membrane by simple diffusion?

Accepted Answer

O$$_2$$

Question 8

A cell uses receptor-mediated endocytosis to import cholesterol from the bloodstream. Which feature makes this process highly specific?

Accepted Answer

The binding of cholesterol to specific receptor proteins on the cell surface

Question 9

Which of the following statements about membrane proteins is FALSE?

Accepted Answer

All membrane proteins are transmembrane proteins.

Question 10

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

Accepted Answer

Exocytosis

Question 11

A freshwater Paramecium lives in a hypotonic environment. How does it prevent itself from bursting?

Accepted Answer

By using a contractile vacuole to expel excess water

Question 12

Which of the following best describes cotransport?

Accepted Answer

The active transport of one solute indirectly driving the transport of another solute

Question 13

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Cell-to-cell recognition

Question 14

Which of the following scenarios illustrates active transport?

Accepted Answer

Na$$^+$$ ions being pumped out of a neuron against their concentration gradient

Question 15

Which statement about the fluid mosaic model is correct?

Accepted Answer

The membrane is a mosaic of proteins bobbing in a fluid bilayer of phospholipids.

Question 16

Which of the following best explains why plant cells become flaccid in an isotonic solution?

Accepted Answer

There is no net movement of water into the cell, so the cell wall is not pressed tightly by the plasma membrane.

Question 17

Which of the following is TRUE about facilitated diffusion?

Accepted Answer

It moves substances down their concentration gradient with the help of transport proteins.

Question 18

Which of the following is NOT a type of endocytosis?

Accepted Answer

Exocytosis

Question 19

A scientist observes that a certain protein spans the entire plasma membrane and has hydrophobic regions embedded in the membrane core. What type of protein is this?

Accepted Answer

Integral protein

Question 20

Which of the following best describes the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Membrane Structure and Function: Regulating Cellular Traffic

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