Question 1

Refer to the first image. Which part of the phospholipid molecule is responsible for its amphipathic nature?

Accepted Answer

Both the hydrophilic head and hydrophobic tails

Question 2

A mutation changes a polar amino acid to a nonpolar amino acid at the circled site in the channel protein (see second image). What is the most likely effect on channel function?

Accepted Answer

The channel may block polar molecules from passing through

Question 3

Which of the following best describes the function of the sodium-potassium pump (see fourth image, region A)?

Accepted Answer

It moves Na$^+$ out of the cell and K$^+$ into the cell

Question 4

Which of the following molecules can pass through a cell membrane unassisted?

Accepted Answer

Estrogen (a steroid)

Question 5

A drop of red blood cells is placed in a 0.9% NaCl solution. Under the microscope, the cells appear normal (see sixth image). What can you conclude about the tonicity of the solution?

Accepted Answer

The solution is isotonic to the RBC cytosol

Question 6

Which cytoskeletal component interacts with myosin during muscle contraction?

Accepted Answer

Actin microfilaments

Question 7

Which of the following would be expected to be liquid at room temperature?

Accepted Answer

A triglyceride composed of three cis-unsaturated fatty acids

Question 8

Which of the following statements about cell membranes is FALSE?

Accepted Answer

Animal cells have cell membranes, but plant cells do not (they have cell walls instead).

Question 9

Which of the following cell shapes has the smallest surface-to-volume ratio?

Accepted Answer

Sphere

Question 10

GLUT-1 transports glucose ____ its concentration gradient. The shape of GLUT-1 changes due to ____.

Accepted Answer

down; interactions with glucose

Question 11

A protein destined for the mitochondria will have:

Accepted Answer

Neither a NLS nor an ER signal sequence

Question 12

Which of the following is NOT part of the endomembrane system?

Accepted Answer

Mitochondria

Question 13

Steroids are synthesized in the ____.

Accepted Answer

Smooth endoplasmic reticulum

Question 14

Which of the following increases the permeability of a cell membrane?

Accepted Answer

Increasing the temperature of the membrane

Question 15

Which cytoskeletal element and motor protein are involved in transporting vesicles from the rough ER to the Golgi?

Accepted Answer

Microtubules and kinesin

Question 16

Which of the following best explains why a hypotonic solution causes red blood cells to burst?

Accepted Answer

Water moves into the cells by osmosis, increasing turgor pressure

Question 17

Which of the following is the smallest?

Accepted Answer

Virus

Question 18

Which motor protein is responsible for the movement of flagella and cilia?

Accepted Answer

Dynein

Question 19

Which of the following best describes the path phospholipids take through the cell to reach the cell membrane?

Accepted Answer

Smooth ER $\rightarrow$ Golgi $\rightarrow$ cell membrane

Biology 161 Exam 2 Study Guidance: Cell Structure, Membranes, and Transport

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