Q: A nerve cell uses the sodium-potassium pump to maintain its resting potential. Which equation describes the energy required for this active transport?

$$ATP \rightarrow ADP + P_i + \text{energy}$$

Question 1

Which component of the fluid mosaic model is primarily responsible for the selective permeability of cellular membranes?

Accepted Answer

Phospholipid bilayer

Question 2

A researcher observes that a certain molecule can cross the plasma membrane without the assistance of a protein and moves from an area of high concentration to low concentration. Which process is most likely occurring?

Accepted Answer

Simple diffusion

Question 3

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

It increases membrane fluidity at low temperatures and decreases it at high temperatures.

Question 4

A cell is placed in a hypertonic solution. What will happen to the cell, and which principle explains this?

Accepted Answer

The cell will shrink as water leaves by osmosis.

Question 5

Which type of membrane protein is covalently attached to fatty acids and is embedded within the lipid bilayer?

Accepted Answer

Lipid-anchored protein

Question 6

Which equation best represents the net movement of solute during simple diffusion across a membrane?

Accepted Answer

$$J = -D \frac{dC}{dx}$$

Question 7

A nerve cell uses the sodium-potassium pump to maintain its resting potential. Which equation describes the energy required for this active transport?

Accepted Answer

$$ATP ightarrow ADP + P_i + 	ext{energy}$$

Question 8

Which of the following is NOT a function of cellular membranes as listed in Table 5.1?

Accepted Answer

Synthesis of DNA

Question 9

A mutation prevents the formation of cadherin proteins in epithelial cells. Which cellular process would be most directly affected?

Accepted Answer

Cell adhesion

Question 10

Which type of cell junction allows the passage of ions and small molecules directly between adjacent animal cells?

Accepted Answer

Gap junctions

Question 11

Which process requires energy input and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 12

A plant cell is placed in a hypotonic solution. What is the expected outcome and which term describes the pressure that develops?

Accepted Answer

The cell swells; turgor pressure

Question 13

Which of the following best describes the function of integrin proteins?

Accepted Answer

They connect cells to the extracellular matrix.

Question 14

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of LDL cholesterol by cells

Question 15

Which equation describes the osmotic pressure ($$\Pi) $$generated by solute concentration difference across a membrane?

Accepted Answer

$$\Pi = iMRT$$

Question 16

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses channel or carrier proteins to move molecules down their concentration gradient.

Question 17

Which type of anchoring junction is most important for connecting intermediate filaments between adjacent animal cells?

Accepted Answer

Desmosomes

Question 18

Which of the following best explains why ions such as Na$$^+$$ and K$$^+$$ cannot easily cross the lipid bilayer?

Accepted Answer

They are hydrophilic and charged, making them unable to pass through the hydrophobic core.

Question 19

Which of the following is a function of the extracellular matrix (ECM) in animal cells?

Accepted Answer

Providing tensile strength via collagen fibers

Question 20

A scientist observes that a cell is using a symport transporter to move glucose into the cell along with Na$$^+. $$Which type of transport is this and what is the driving force?

Accepted Answer

Secondary active transport; Na$$^+$$ gradient

Cellular Membranes: Structure, Composition, and Functions

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