Learning Checks

Question 1

What is the primary function of active transporters in the cytosol of a cell?

A. import ATP for cellular processes
B. Import DNA
C. Regulate cytosolic pH
D. Regulate pressure

Answer 1

C. Regulate cytosolic pH

Question 2

Cytosolic enzymes function most efficiently at what pH?

Answer 2

7.2

Question 3

How does an uncharged molecule move through a membrane during passive transport?

A. ATP
B. Concentration gradient
C. Electrochemical gradient
D. Ion coupling

Answer 3

B. Concentration gradient

Question 4

What is the responsibility of the concentration gradient?

Answer 4

driving an uncharged molecule acorss a cellular membrane

Question 5

What happens if the concentration of an uncharged molecule is higher on the inside of the cell than on the outside?

Answer 5

the molecule will be moved outside to the area of lower concentration

Question 6

What happens if the concentration of an uncharged molecule is higher outside the cell than inside?

Answer 6

the molecule will be moved inside to the area of lower concentration.

Question 7

Active transport requires energy to move substances against a concentration or electrical gradient. What is the primary source of energy for primary active transport?

A. Adenosine triphosphate
B. Adrenaline
C. Norepinephrine
D. Sodium-glucose cotransporter

Answer 7

A. Adenosine triphosphate

Question 8

What is the source of energy for primary active transport?

Answer 8

Adenosine triphosphate (ATP)

Question 9

What is the source of energy for secondary active transport?

Answer 9

requires a shared carrier protein, or cotransporter, such as sodium glucose cotransporter.

Question 10

Primary active transport involves an ATP-powered pump and what other molecules?

A. Potassium and calcium
B. Potassium and chloride
C. Sodium and calcium
D. Sodium and potassium

Answer 10

D. Sodium and potassium

Question 11

What is an example of secondary active transport?

A. Electron transport chain
B. Photosynthesis
C. Sodium-calcium antiporter
D. Sodium-potassium pump

Answer 11

C. Sodium-calcium antiporter

Question 12

Give examples of primary active transport?

Answer 12

1. Photosynthesis
2. Sodium-Potassium Pump
3. Electron Transport Chain

Question 13

Diffusion is a mechanism by which molecules are transported across the cell membrane. Several factors can affect the rate of diffusion. Which description accurately explains one of these factors?

A. Greater differences between concentrations cause slower diffusion.
B. Higher temperature increases the rate of diffusion.
C. Increased density of the solvent causes more rapid diffusion.
D. Larger molecules diffuse more quickly.

Answer 13

B. Higher temperature increases the rate of diffusion.

EXPLANATION:

1. Higher temperatures increase energy and the movement of molecules, increasing the rate of diffusion.
2. With greater differences between concentrations, the rate of diffusion is decreased.
3. It is more difficult for larger molecules to move within the solvent, so the rate of diffusion is slowed. 4. Similarly, increased density of the solvent also decreases the rate of diffusion.