Question 1

Which of the following best explains why unsaturated fatty acids increase membrane fluidity at lower temperatures?

Accepted Answer

Their double bonds create kinks, preventing tight packing of phospholipid tails.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the tonicity of the solution and the direction of water movement?

Accepted Answer

The solution is hypotonic; water moves into the cell.

Question 3

Which of the following substances would most likely require a transport protein to cross the plasma membrane?

Accepted Answer

Glucose

Question 4

In the fluid mosaic model, what does the term 'mosaic' refer to?

Accepted Answer

The presence of various proteins, lipids, and carbohydrates embedded in the membrane.

Question 5

Which of the following best describes the difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion uses transport proteins to move substances down their concentration gradient.

Question 6

A plant cell is placed in a hypertonic solution. What will most likely happen to the cell?

Accepted Answer

It will lose water and undergo plasmolysis.

Question 7

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins are embedded within the bilayer and can have hydrophilic and hydrophobic regions.

Question 8

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

Accepted Answer

It decreases membrane fluidity by restraining phospholipid movement.

Question 9

Which of the following is an example of active transport?

Accepted Answer

Movement of $$Na^+$$ ions from low to high concentration using ATP.

Question 10

A cell has a membrane potential of $$-70\ \mathrm{mV}. $$Which side of the membrane is more negative, and what is the main cause of this potential?

Accepted Answer

The inside is more negative due to the distribution of cations and anions.

Question 11

Which process is responsible for the uptake of large particles, such as bacteria, by a white blood cell?

Accepted Answer

Phagocytosis

Question 12

Which of the following best describes selective permeability of the plasma membrane?

Accepted Answer

Some substances cross more easily than others due to the lipid bilayer and transport proteins.

Question 13

Which of the following scenarios best illustrates cotransport in plant cells?

Accepted Answer

A proton pump uses ATP to move $$H^+$$ out of the cell, and the return of $$H^+$$ down its gradient drives the uptake of sucrose.

Question 14

Which of the following best explains why ions such as $$Na^+$$ and $$K^+$$ cannot cross the lipid bilayer unaided?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the bilayer.

Question 15

Which of the following is true about facilitated diffusion by channel proteins?

Accepted Answer

It allows specific molecules or ions to pass through hydrophilic corridors.

Question 16

A cell is placed in an isotonic solution. What will happen to the cell's volume over time?

Accepted Answer

It will remain unchanged as water moves in and out at equal rates.

Question 17

Which of the following best describes the function of carbohydrates attached to cell membrane proteins?

Accepted Answer

They serve as recognition sites for cell-cell interactions.

Question 18

Which of the following is a key difference between exocytosis and endocytosis?

Accepted Answer

Exocytosis releases materials from the cell, while endocytosis brings materials into the cell.

Question 19

Which of the following best explains why the movement of water across a membrane is considered osmosis?

Accepted Answer

Water moves from low to high solute concentration through a selectively permeable membrane.

Question 20

Which of the following is true about the lateral movement of phospholipids in the membrane?

Accepted Answer

Phospholipids move laterally within the same leaflet, contributing to membrane fluidity.

Membrane Structure and Transport: Study Guide for General Biology

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