$$\text{Water moves from a region of lower solute concentration to a region of higher solute concentration}$$

Question 1

Which property of the plasma membrane allows it to regulate the movement of substances into and out of the cell?

Accepted Answer

Selective permeability

Question 2

What is the main structural component of the plasma membrane that forms a bilayer?

Accepted Answer

Phospholipids

Question 3

Which of the following best describes the amphipathic nature of membrane lipids?

Accepted Answer

They have both hydrophobic and hydrophilic regions

Question 4

According to the fluid mosaic model, what is the arrangement of proteins in the plasma membrane?

Accepted Answer

Proteins are individually inserted into the phospholipid bilayer, with hydrophilic regions exposed to water

Question 5

Which type of movement is most common for phospholipids within the plasma membrane?

Accepted Answer

Lateral movement

Question 6

How do cis-double bonds in hydrocarbon chains affect membrane fluidity?

Accepted Answer

They make it more difficult to pack the chains together, increasing fluidity

Question 7

What is the effect of cholesterol on membrane fluidity at warm temperatures (e.g., 37°C)?

Accepted Answer

Cholesterol restrains movement of phospholipids, decreasing fluidity

Question 8

An organism is discovered living in extremely cold environments. Which adaptation would you expect in its membrane phospholipids?

Accepted Answer

More unsaturated hydrocarbon tails

Question 9

Which of the following molecules can most easily cross the plasma membrane without the aid of a transport protein?

Accepted Answer

Nonpolar molecules such as hydrocarbons

Question 10

What is the primary function of aquaporins in the plasma membrane?

Accepted Answer

Facilitate rapid diffusion of water across the membrane

Question 11

Which equation correctly represents the direction of water movement during osmosis?

Accepted Answer

$$	ext{Water moves from a region of lower solute concentration to a region of higher solute concentration}$$

Question 12

A plant cell placed in a hypotonic solution will:

Accepted Answer

Become turgid as water enters the cell

Question 13

Which of the following best explains why polar molecules such as glucose cannot easily cross the lipid bilayer?

Accepted Answer

The hydrophobic core of the bilayer repels polar molecules

Question 14

Which type of membrane protein is completely embedded and spans the membrane multiple times?

Accepted Answer

Integral protein

Question 15

What is the role of carbohydrates attached to proteins and lipids on the external side of the plasma membrane?

Accepted Answer

Cell recognition and adhesion

Question 16

Which scenario best illustrates the concept of membrane asymmetry?

Accepted Answer

Different proteins and carbohydrates are distributed on the inner and outer surfaces of the membrane

Question 17

If a red blood cell is placed in a hypertonic solution, what will happen?

Accepted Answer

The cell will lose water and shrink

Question 18

Which process requires energy and a transport protein to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 19

Which of the following is a real-world example of membrane protein movement visualization?

Accepted Answer

Labeling proteins with rhodamine/fluorescein and tracking fluorescence

Question 20

Which equation best represents the relationship between solute concentration and water movement in osmosis?

Accepted Answer

$$	ext{Water moves from an area of high water potential to low water potential}$$

Membrane Structure and Function: Study Notes for General Biology

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