Q: Which equation best represents the net movement of water during osmosis?

$\text{Water moves from an area of higher water potential to lower water potential}$

Q: A cell uses the sodium-potassium pump to maintain ion gradients. Which equation describes the energy requirement for this process?

$\text{ATP} \rightarrow \text{ADP} + \text{P}_i$

Question 1

Which of the following statements best describes the fluid mosaic model of the cell membrane?

Accepted Answer

The membrane consists of a phospholipid bilayer with proteins and other molecules that can move laterally within the layer.

Question 2

How does cholesterol affect membrane fluidity at low temperatures?

Accepted Answer

Cholesterol increases membrane fluidity by preventing phospholipids from packing too closely.

Question 3

A cell membrane is composed of phospholipids with unsaturated fatty acid tails. What effect does this have on membrane fluidity at room temperature?

Accepted Answer

It increases fluidity because the kinks in unsaturated tails prevent tight packing.

Question 4

Which of the following molecules is most likely to diffuse directly through the phospholipid bilayer without the aid of a transport protein?

Accepted Answer

O$_2$

Question 5

Channel proteins and carrier proteins both facilitate diffusion. Which statement correctly distinguishes between them?

Accepted Answer

Channel proteins provide a passageway for molecules, while carrier proteins undergo conformational changes to transport molecules.

Question 6

Facilitated diffusion differs from active transport in which of the following ways?

Accepted Answer

Facilitated diffusion moves molecules down their concentration gradient without energy input.

Question 7

A red blood cell is placed in a hypotonic solution. Predict the direction of water movement and the likely outcome for the cell.

Accepted Answer

Water will move into the cell, causing it to swell and possibly burst.

Question 8

Which equation best represents the net movement of water during osmosis?

Accepted Answer

$	ext{Water moves from an area of higher water potential to lower water potential}$

Question 9

Which of the following scenarios requires active transport?

Accepted Answer

Uptake of glucose into a cell against its concentration gradient.

Question 10

A cell uses the sodium-potassium pump to maintain ion gradients. Which equation describes the energy requirement for this process?

Accepted Answer

$	ext{ATP} ightarrow 	ext{ADP} + 	ext{P}_i$

Question 11

Which of the following best explains why polar molecules such as glucose require transport proteins to cross the cell membrane?

Accepted Answer

Polar molecules are repelled by the hydrophobic core of the phospholipid bilayer.

Question 12

A patient is given intravenous fluids that are isotonic to their blood plasma. What effect will this have on their red blood cells?

Accepted Answer

Red blood cells will remain unchanged.

Question 13

Which of the following is a correct statement about facilitated diffusion?

Accepted Answer

It involves specific transport proteins that increase the rate of diffusion.

Question 14

A cell is placed in a solution with a higher concentration of solutes than inside the cell. What type of solution is this, and what will happen to the cell?

Accepted Answer

Hypertonic; the cell will lose water and shrink.

Question 15

Which process is responsible for the movement of water across a cell membrane?

Accepted Answer

Osmosis

Question 16

Which of the following best describes the role of temperature in membrane fluidity?

Accepted Answer

Increasing temperature increases membrane fluidity.

Question 17

A cell is actively transporting ions against their concentration gradient. Which of the following is true?

Accepted Answer

The process requires energy, usually from ATP hydrolysis.

Question 18

Which of the following statements about channel proteins is correct?

Accepted Answer

Channel proteins allow specific molecules to pass through by forming hydrophilic pores.

Question 19

Which of the following best explains why a cell membrane is described as 'selectively permeable'?

Accepted Answer

It allows some molecules to pass while restricting others based on size, charge, and polarity.

Cell Membrane Structure and Transport Mechanisms

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