Q: Which equation best represents the amphipathic structure of a phospholipid?

$$\text{Phospholipid} = \text{Glycerol} + 2 \text{Fatty Acids} + \text{Phosphate Group}$$

Question 1

Which component of the plasma membrane is primarily responsible for its selective permeability?

Accepted Answer

Phospholipid bilayer

Question 2

What is the main function of cholesterol in the plasma membrane at low temperatures?

Accepted Answer

It prevents tight packing of phospholipids, maintaining fluidity.

Question 3

Which of the following best describes the amphipathic nature of phospholipids?

Accepted Answer

They have two hydrophobic tails and a hydrophilic head.

Question 4

A fish living in extremely cold waters is likely to have plasma membranes with which type of lipid composition?

Accepted Answer

High proportion of unsaturated fatty acids

Question 5

Which of the following statements about the fluid mosaic model is correct?

Accepted Answer

The membrane is held together by weak hydrophobic interactions, allowing movement.

Question 6

What is the role of membrane carbohydrates such as glycoproteins and glycolipids?

Accepted Answer

They are important for cell-to-cell recognition.

Question 7

Which equation best represents the amphipathic structure of a phospholipid?

Accepted Answer

$$	ext{Phospholipid} = 	ext{Glycerol} + 2 	ext{Fatty Acids} + 	ext{Phosphate Group}$$

Question 8

Which type of membrane protein is embedded within the lipid bilayer and often spans the entire membrane?

Accepted Answer

Integral protein

Question 9

How do unsaturated hydrocarbon tails in phospholipids affect membrane fluidity at low temperatures?

Accepted Answer

They increase fluidity by preventing tight packing.

Question 10

Which structure in plant cells allows cytosol to pass between adjacent cells?

Accepted Answer

Plasmodesmata

Question 11

A mutation causes a cell to produce only saturated fatty acids in its plasma membrane. What is the most likely consequence at low temperatures?

Accepted Answer

The membrane will become less fluid and more rigid.

Question 12

Which of the following is NOT a function of the plant cell wall?

Accepted Answer

Cell-to-cell recognition

Question 13

Which of the following best explains why plasma membranes are described as 'fluid'?

Accepted Answer

Phospholipids and proteins can move laterally within the layer.

Question 14

Which of the following is a correct statement about peripheral proteins?

Accepted Answer

They are loosely bonded to the surface of the membrane.

Question 15

Which of the following would most likely increase the permeability of a plasma membrane to water?

Accepted Answer

Increasing the number of integral proteins that form channels

Question 16

A scientist observes that a cell membrane is more fluid at higher temperatures. Which component is most likely responsible for reducing this fluidity?

Accepted Answer

Cholesterol

Question 17

Which of the following is a real-world consequence of a defective plasma membrane in human red blood cells?

Accepted Answer

Impaired oxygen transport due to loss of membrane integrity

Question 18

Which equation best represents the effect of temperature on membrane fluidity?

Accepted Answer

$$	ext{Fluidity} = f(	ext{Temperature}, 	ext{Lipid Composition}, 	ext{Cholesterol})$$

Question 19

Which of the following is a direct result of the amphipathic nature of phospholipids in biological membranes?

Accepted Answer

Formation of a bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward

Question 20

Which of the following is a likely adaptation in the plasma membrane of Antarctic fish living in cold, low oxygen waters?

Accepted Answer

Increased proportion of unsaturated fatty acids to maintain membrane fluidity

Plasma Membranes and Membrane Permeability: Structure and Function

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