Chapter 3. 3·4–3·7 Cell membranes are gatekeepers.

Show What You Know - Self Quiz

true

You must read each slide, and complete any questions on the slide, in sequence.

Instructions

Check your understanding of concepts from 3·4–3·7 Cell membranes are gatekeepers by answering the following questions.

1.

1. What cellular structure makes it possible for a cell to differ structurally and biochemically from its surroundings?

plasma membrane

endoplasmic reticulum

phospholipid

nucleus

cell wall

Correct! (See section 3·4 Every cell is bordered by a plasma membrane.)

Incorrect. (See section 3·4 Every cell is bordered by a plasma membrane.)

2.

2. The role of cholesterol in the plasma membrane of animal cells is to:

keep the plasma membrane flexible, especially at low temperatures.

form thickened membranes that are stronger and less easily punctured.

help cells recognize each other, acting as a "fingerprint" on the outside of the cell.

act as a receptor for hormones such as estrogen and testosterone.

help transport polar molecules across the plasma membrane.

Correct! (See section 3·5 Molecules embedded in the plasma membrane help it perform its functions.)

Incorrect. (See section 3·5 Molecules embedded in the plasma membrane help it perform its functions.)

3.

3. The diagram above shows the action of beta-blockers in reducing anxiety. In this diagram, the green triangles represent ________________, the yellow figures represent ______________, and the purple ovals represent ______________.

mucus; beta-blocker chemicals; beta-receptors

adrenaline; beta-blocker chemicals; beta-receptors

beta-blocker chemicals; mucus; beta-receptors

beta-blocker chemicals; adrenaline; beta-receptors

adrenaline; beta-receptors; beta-blocker chemicals

Correct! (See section 3·6 Faulty membranes can cause diseases.)

Incorrect. (See section 3·6 Faulty membranes can cause diseases.)

4.

In the diagram above, the round knobby structures are _______________ and the purple post-like structures with semi-circular receptors at the top are ________________.

beta-blocker chemicals; adrenaline molecules

beta-blocker chemicals; beta receptors

HIV particles; CD4 markers

adrenaline molecules; beta receptors

HIV particles; liver cell molecular fingerprint

Correct. (See section 3·7 Membrane surfaces have a “fingerprint” that identifies the cell.)

Incorrect. (See section 3·7 Membrane surfaces have a “fingerprint” that identifies the cell.)

5.

5. The function of cholesterol in membranes is:

to reduce membrane fluidity at higher temperatures.

to reduce membrane fluidity at lower temperatures.

to increase membrane fluidity at higher temperatures.

to increase membrane permeability at lower temperatures.

There is no function of cholesterol; it is tolerated in low amounts in mammalian cells.

Correct. (See section 3·5 Molecules embedded in the plasma membrane help it perform its functions.)

Incorrect. (See section 3·5 Molecules embedded in the plasma membrane help it perform its functions.)

Activity results are being submitted...