Q: Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

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

Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic bilayer of phospholipids with proteins and lipids organized in specialized, long-lasting patches.

Question 2

Phospholipids are described as amphipathic molecules. What does this mean?

Accepted Answer

They contain both hydrophobic and hydrophilic regions.

Question 3

Which of the following statements about membrane proteins is TRUE?

Accepted Answer

Most membrane proteins are amphipathic, allowing them to protrude from the membrane.

Question 4

How does cholesterol affect membrane fluidity at human body temperature ($$37^\circC$$)?

Accepted Answer

It increases membrane fluidity by preventing close packing of phospholipids.

Question 5

Which adaptation would you expect in the membrane lipid composition of Arctic cod living in cold water?

Accepted Answer

High levels of unsaturated fats to maintain membrane fluidity.

Question 6

A cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will lose water and shrink.

Question 7

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

Accepted Answer

Oxygen ($$O_2)$$

Question 8

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses transport proteins to move substances down their concentration gradient.

Question 9

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Cell-cell recognition, such as in immune response and blood typing.

Question 10

The sodium-potassium pump ($$Na^+/K^+$$ pump) is an example of:

Accepted Answer

Active transport

Question 11

Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

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

Question 12

Which of the following statements about electrochemical gradients is correct?

Accepted Answer

They combine both the chemical concentration gradient and the electrical potential across the membrane.

Question 13

What is the main function of aquaporins in kidney cells?

Accepted Answer

To facilitate the passive diffusion of water, allowing the kidney to reclaim water from urine.

Question 14

Which process allows large molecules such as proteins to exit a cell?

Accepted Answer

Exocytosis

Question 15

Which of the following is TRUE about G-protein-coupled receptors (GPCRs)?

Accepted Answer

They work with G proteins to transmit signals from extracellular molecules.

Question 16

What is the role of protein kinases in signal transduction pathways?

Accepted Answer

They transfer phosphate groups from ATP to proteins, activating them.

Question 17

Which of the following is a second messenger commonly involved in signal transduction?

Accepted Answer

Cyclic AMP ($$cAMP)$$

Question 18

A patient with cholera is losing large amounts of water and salts in their intestines. Which molecular mechanism is responsible for this symptom?

Accepted Answer

Cholera toxin keeps the G protein in its active form, continuously stimulating adenylyl cyclase to produce $$cAMP$$, which causes cells to secrete water and salts.

Question 19

Which of the following best explains why plant cells become turgid in a hypotonic solution?

Accepted Answer

Water enters the cell, and the cell wall pushes back, creating turgor pressure.

Membrane Transport & Cell Signaling (Chapter 5) – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard