Cell Biology Chapter 4 Quiz

Questions and Answers

Exocytosis is a process by which cells:

Release substances from the cell via carrier proteins.

Bring in substances from the outside via vesicles.

Bring in substances from the outside via pores in the cell membrane.

Release substances from the cell via vesicles. (correct)

Release substances from the cell through pores in the cell membrane.

Certain white blood cells engulf microorganisms and bring them in to digest them. This process is best described as:

Diffusion.

Pinocytosis.

Receptor-mediated exocytosis.

Phagocytosis. (correct)

Osmosis.

Which of the following statements about receptor-mediated endocytosis is TRUE?

It is used to transport material out of the cell.

It is not specific.

It involves clathrin-coated pits. (correct)

It involves transport of material into the cell through pores in the cell membrane.

None of the above.

If the material the cell takes in is liquid, the process is termed pinocytosis.

True Signup and view all the answers

Low-density lipoprotein is brought into the cell by receptor-mediated endocytosis.

True Signup and view all the answers

Simple diffusion is defined as the movement of:

Molecules from areas of higher concentration to areas of lower concentration. Signup and view all the answers

When sugar is mixed with water, equilibrium is reached when:

The dissolved sugar molecules are evenly distributed throughout the solution. Signup and view all the answers

The rate of diffusion is affected by which of the following?

A, B and C Signup and view all the answers

The molecules in a solid lump of sugar do not move.

False Signup and view all the answers

Diffusion is one of the processes whereby materials are exchanged between a cell and its environment.

True Signup and view all the answers

Facilitated diffusion requires:

Carrier proteins. Signup and view all the answers

Facilitated diffusion occurs:

In either direction depending on the concentration gradient of the molecule. Signup and view all the answers

Facilitated diffusion is used to transport:

Sugars and amino acids. Signup and view all the answers

Unlike simple diffusion, facilitated diffusion requires energy expenditure by the cell.

False Signup and view all the answers

Facilitated diffusion requires a specific transporter for a specific molecule.

True Signup and view all the answers

Osmosis is best defined as the movement of:

Water molecules across a membrane from an area of high water concentration to an area of lower concentration. Signup and view all the answers

Which of the following will pass through a cell membrane most easily?

Small nonpolar molecules Signup and view all the answers

A red blood cell placed in a hypertonic medium will:

Shrink. Signup and view all the answers

A 5% urea solution is hypotonic to a 10% urea solution.

True Signup and view all the answers

If a cell is placed in an isotonic medium, there will be no net movement of water.

True Signup and view all the answers

The sodium-potassium pump functions to pump:

Sodium ions out of the cell and potassium ions into the cell. Signup and view all the answers

What is the source of energy used to power the sodium-potassium pump?

Breakdown of ATP Signup and view all the answers

During one cycle, the sodium-potassium pump binds and moves:

3 Na+ and 2 K+. Signup and view all the answers

The sodium-potassium pump is a trans-membrane protein.

True Signup and view all the answers

The binding and release of sodium or potassium ions are due to conformational changes in the protein.

True Signup and view all the answers

Study Notes

Exocytosis and Endocytosis

Exocytosis releases substances from cells via vesicles, rather than through membrane pores or carrier proteins.
Phagocytosis is the mechanism used by white blood cells to engulf and digest microorganisms.
Receptor-mediated endocytosis specifically requires clathrin-coated pits to transport materials into the cell.

Types of Diffusion

Pinocytosis refers to the uptake of liquids by cells.
Low-density lipoprotein (LDL) enters cells through receptor-mediated endocytosis.
Simple diffusion occurs as molecules move from areas of higher concentration to lower concentration, facilitated by factors such as temperature and molecule size.

Equilibrium in Solutions

Equilibrium is achieved when dissolved sugar molecules are evenly distributed in water.
The rate of diffusion is influenced by temperature, size of molecules, and steepness of concentration gradients.

Facilitated Diffusion

Facilitated diffusion utilizes carrier proteins and does not require energy expenditure, differing from active transport mechanisms.
This process can transport sugars and amino acids in either direction based on concentration gradients.

Osmosis and Water Movement

Osmosis is the movement of water molecules across a membrane from areas of high to low water concentration.
Small nonpolar molecules easily pass through cell membranes, while larger or polar molecules face more difficulty.

Cell Reactions to Tonicity

A red blood cell in a hypertonic solution will shrink due to water moving out.
Solutions with different concentrations, such as a 5% urea solution being hypotonic to a 10% solution, can affect cell volumes.
Cells in an isotonic medium experience no net movement of water.

Sodium-Potassium Pump

This pump actively transports sodium ions out of the cell and potassium ions into the cell, powered by the breakdown of ATP.
During each cycle, it moves 3 sodium ions out and 2 potassium ions in, changing conformation to bind and release these ions effectively.
The sodium-potassium pump is a trans-membrane protein essential for maintaining cellular ion gradients.

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Description

Test your understanding of key cell biology concepts in Chapter 4, including exocytosis and related processes. This quiz will help reinforce your knowledge about how cells communicate and transport substances. Perfect for students revising cell biology topics.