Cell Membrane & Transport Review

Based on the arrangement of the hydrophilic heads and hydrophobic tails of the cell membrane bilayer, which of the following can cross the cell membrane WITHOUT energy? Select ALL that apply.

• large molecules

• small, uncharged molecules

• lipid-soluble molecules

• charged molecules

Large substance can move across the cell membrane by bulk transport either into or out of the cell. Bulk transport is a form of active transport that requires energy.

What is the process in which a cell creates a vesicle to surround and engulf a particle to bring it INTO the cell?

• exocytosis

• endocytosis

• osmosis

• simple diffusion

• facilitated diffusion

Determine if each of the listed molecules or ions would need to be transported across the membrane by passive diffusion or active transport.​ ​​ ​ ​ ​ ​

Groups:

(a) Simple Diffusion

,

(b) Facilitated Diffusion or Active Transpor

• Na+

• Ca2+

• C6H12O6 (glucose)

• O2

• CO2

A cell's surface-area-to-volume ratio is the most accurate determinant of the ease with which diffusion occurs. The greater the surface-area-to-volume ratio, the rate of diffusion.

Which of the following cubes has the greatest rate of diffusion?

• 1 cm cell

• 2 cm cell

• 3 cm cell

Tags

NGSS.MS-LS1-2

Tonicity refers to the concentration of solutes. Observe the diagram.

If a cell is in a HYPOTONIC environment, this means that:

• there are fewer solutes inside the cell than in the extracellular environment.

• there is an equal amount of solutes inside as outside the cell.

• there is more solute outside the cell than in the cell.

• there is less solute outside the cell than inside of the cell.

Active transport involves the transport of molecules across a cell membrane.

In order to establish and maintain a concentration gradient,

• free energy is used to drive molecules back-and-forth across the transmembrane protein.

• free energy is used to drive molecules across a transmembrane protein against the concentration gradient.

• no free energy is required.

• there must be an equal quantity of molecules on both sides of the membrane.

The cell membrane is comprised of a bilayer that is both hydrophobic and hydrophilic.

What is the purpose of this double layered sheet? Select ALL that apply.

• To protect the organelles from the surrounding environment.

• To provide flexible support to the cell.

• To regulate the molecules and ions that are able to enter or exit the cellular environment.

• To provide a rigid structure to the cell.

The phospholipids and embedded proteins of the cell membrane work together in order to allow for the transport of molecules across the membrane.

Which of the following statements BEST describes how molecules are transported across membranes.

• All molecules transport across the membrane without any assistance.

• All molecules transport across the membrane with the use of a protein channel.

• All molecules transport across the membrane with the use of a receptor molecule.

• Some molecules transport across the membrane with the help of a protein channel and some do not.

Protein channels found embedded in the cellular membrane (like the diagram) allow for:

• facilitated diffusion of molecules or ions through the cell membrane from areas of low concentration to areas of high concentration.

• facilitated diffusion of molecules or ions through the cell membrane from areas of high concentration to areas of low concentration.

• passive transport of molecules or ions through the cell membrane from areas of high concentration to areas of low concentration.

• passive transport of molecules or ions through the cell membrane from areas of low concentration to areas of high concentration.

The cell membrane is ​ (a)   to molecules and ions. Small, hydrophobic, nonpolar molecules can be transported into or out of the cell via ​ (b)   . Larger, polar molecules or ions, however, must use ​ (c)   which requires the presence of ​ (d)   or ​ (e)   .

• selectively permeable
• diffusion
• facilitated diffusion
• carrier proteins
• protein channels
• nonpermeable
• active transport
• facilitated proteins
• enzymes
• molecular gradients

Tags

NGSS.HS-LS2-3