Question 1

Which of the following best describes facilitated diffusion across a cell membrane?

Accepted Answer

It involves the movement of solutes down their concentration gradient with the assistance of transport proteins.

Question 2

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

Accepted Answer

The cell will swell and may burst (lyse) as water enters.

Question 3

Which equation correctly represents the free energy change ($$\Delta G) $$for the movement of a non-charged solute across a membrane?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[S]_{out}}{[S]_{in}} \right)$$

Question 4

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

Accepted Answer

Glycerol (MW = 92)

Question 5

What is the primary function of the Na+/K+ ATPase in animal cells?

Accepted Answer

To maintain asymmetric distribution of Na+ and K+ ions across the plasma membrane using ATP hydrolysis.

Question 6

Which statement about active transport is correct?

Accepted Answer

It moves solutes against their concentration gradient and requires energy input.

Question 7

A carrier protein that transports two solutes in opposite directions across a membrane is called a:

Accepted Answer

Antiporter

Question 8

Which of the following best explains why ions such as Na+ and Cl- require transport proteins to cross the plasma membrane?

Accepted Answer

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

Question 9

Which of the following is true regarding the kinetics of simple diffusion versus facilitated diffusion?

Accepted Answer

Simple diffusion rate increases linearly with solute concentration gradient, while facilitated diffusion shows a hyperbolic relationship.

Question 10

Which of the following is NOT a function of active transport in cells?

Accepted Answer

Facilitating the passive movement of oxygen gas

Question 11

The movement of water across a selectively permeable membrane toward a region of higher solute concentration is called:

Accepted Answer

Osmosis

Question 12

Which of the following best describes the alternating conformation model for glucose transport by GLUT1?

Accepted Answer

GLUT1 binds glucose, changes conformation, and releases glucose on the opposite side of the membrane.

Question 13

Which of the following statements about membrane permeability is correct?

Accepted Answer

Large nonpolar molecules such as steroids can cross membranes easily.

Question 14

In a mammalian neuron, the ratio $$[K^+]_{in}/[K^+]_{out} is $$about 30:1 and $$[Na^+]_{in}/[Na^+]_{out} is $$about 0.08:1. What does this indicate about the distribution of these ions?

Accepted Answer

Potassium is more concentrated inside the cell and sodium is more concentrated outside.

Question 15

Which of the following is a direct source of energy for active transport by the Na+/K+ ATPase?

Accepted Answer

Hydrolysis of ATP

Question 16

Which of the following best describes the directionality of active transport compared to diffusion?

Accepted Answer

Active transport has intrinsic directionality, moving solutes against their gradient.

Question 17

Which of the following is true about coupled transport?

Accepted Answer

Symport moves two solutes in the same direction across the membrane.

Question 18

Which of the following is a property of channel proteins?

Accepted Answer

They form hydrophilic channels that allow specific ions or molecules to pass through.

Question 19

Which of the following statements about the rate of simple diffusion is correct?

Accepted Answer

It is directly proportional to the concentration difference across the membrane.

Question 20

Which of the following is a real-life example of facilitated diffusion in erythrocytes?

Accepted Answer

Glucose entering the cell via the GLUT1 transporter.

Transport Across Membranes: Overcoming the Permeability Barrier (Cell Biology Chapter 8 Study Notes)

Guida di studio - Domande di pratica

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