Q: Which of the following equations best represents the amphipathic nature of a phospholipid?

$$\text{Phospholipid} = \text{Polar Head} + 2 \times \text{Non-polar Tails}$$

Question 1

Which of the following best explains why phospholipids spontaneously form bilayers in aqueous environments?

Accepted Answer

Their amphipathic nature causes hydrophilic heads to interact with water and hydrophobic tails to avoid water.

Question 2

A scientist discovers a new cell membrane that contains isoprenoid tails in its phospholipids. To which domain of life does this organism most likely belong?

Accepted Answer

Archaea

Question 3

Which of the following is NOT a function of the plasma membrane?

Accepted Answer

Synthesizing DNA for cell division

Question 4

Which statement best describes the Fluid Mosaic Model of membrane structure?

Accepted Answer

Membranes are composed of a diverse mixture of lipids, proteins, and carbohydrates that move laterally within the layer.

Question 5

Which of the following is a correct pairing of a membrane lipid and its primary location?

Accepted Answer

Phytosterol – plant cell membranes

Question 6

A mutation causes a cell to produce only saturated fatty acids in its membrane phospholipids. What is the most likely effect on the membrane?

Accepted Answer

The membrane will become less flexible and more rigid.

Question 7

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

Accepted Answer

The two layers of the bilayer contain different types of phospholipids and proteins.

Question 8

Which property of membranes allows a cell to repair itself after minor damage?

Accepted Answer

The ability of lipids to move laterally and reform a continuous surface

Question 9

Feedback inhibition in metabolic pathways is best described as:

Accepted Answer

The final product of a pathway inhibits an enzyme that acts early in the pathway.

Question 10

Which of the following equations best represents the amphipathic nature of a phospholipid?

Accepted Answer

$$	ext{Phospholipid} = 	ext{Polar Head} + 2 	imes 	ext{Non-polar Tails}$$

Question 11

Which of the following is a real-world example of membrane compartmentalization increasing cellular efficiency?

Accepted Answer

Mitochondria having inner and outer membranes to separate metabolic processes

Question 12

Which of the following statements about membrane lipids is TRUE?

Accepted Answer

Archaea have membrane lipids with isoprenoid tails instead of fatty acids.

Question 13

A cell membrane is measured to be 5 nm thick. Which structure is most likely being observed?

Accepted Answer

A lipid bilayer of a plasma membrane

Question 14

Which of the following best describes why cholesterol is important in animal cell membranes?

Accepted Answer

It increases membrane rigidity and stability.

Question 15

Which of the following is a consequence of the diversity of membrane lipids?

Accepted Answer

Different membranes have different properties suited to their functions.

Question 16

Which of the following is a correct description of a triglyceride?

Accepted Answer

A lipid composed of three fatty acids linked to glycerol

Question 17

Which property of membranes allows cells to increase their surface area as they grow?

Accepted Answer

Expandability due to the addition of new membrane lipids

Question 18

Which of the following best explains why the hydrophobic effect is critical for membrane formation?

Accepted Answer

It drives the non-polar tails of phospholipids to avoid water, forming the bilayer interior.

Question 19

Which of the following is a direct result of feedback inhibition in a metabolic pathway?

Accepted Answer

The pathway slows down or stops when enough product is made.

Week 5 - Oct 1

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