Plasma Membrane and Passive Transport

Which cell organelle determines what molecules can enter and leave the cell?

• Cytoplasm

• Ribosome

• Plasma membrane

• Vacuole

The phospholipid bilayers in cell membranes are formed by phospholipid molecules that self-arrange head-to-head

• True

• False

Answer explanation

The phospholipid bilayer self-arrange tail-to-tail.

All of the following are principal components of the plasma membrane EXCEPT for:

• Carbohydrate

• Lipids

• Nucleic acids

• Proteins

Answer explanation

The principal components of the plasma membrane are lipids, proteins and carbohydrates.

This image is an example of a phospholipid. Which part of a phospholipid is HYDROPHILIC?

• The phosphate "head"

• The lipid "tail"

• The phosphate "tail"

• The lipid "head"

The plasma membrane is described as a fluid mosaic. Which of the following DOES NOT explain the mosaic nature of the plasma membrane?

• It contains different components like phospholipids, cholesterol, proteins, and carbohydrates

• There are proteins embedded in the lipid bilayer

• Its components float along with all the lipids in the plasma membrane

• There are carbohydrates bound to proteins or lipids

Answer explanation

The components that float along with all the lipids in the membrane describe the fluid nature of plasma membrane.

Passive transport involves the movement of particles from an area of _____ concentration to an area of ______ concentration.

• HIGH, LOW

• LOW, HIGH

• LOW, LOW

• HIGH, HIGH

 

Which two molecules are most likely to cross a cell's phospholipid bilayer by simple diffusion?

• Sugar molecules

• Oxygen (O2)

• Potassium ions

• Carbon Dioxide (O2)

Which of the following accurately describes the end result of diffusion?

• Molecules stop moving through the cell membrane

• Molecules move into a cell at the same rate as molecules move out of the cell

• Molecules move into a cell faster than they move out of a cell

• Molecules move out of a cell faster than they move into the cell

Which structure of the plasma membrane serves as a transport protein during facilitated diffusion?

• A

• B

• C

• D

• E

Answer explanation

The structure labelled as D is an integral protein known as an ion channel. It is a channel protein that provides a channel which ions can use as a passageway through a membrane.

Which of the following describes the difference between simple diffusion and facilitated diffusion through a cellular membrane?

• Simple diffusion moves particles from an area of low concentration to high concentration; facilitated diffusion moves particles in the opposite direction.

• Simple diffusion moves particles in the direction of the concentration gradient; facilitated diffusion moves particles against the concentration gradient.

• Simple diffusion moves particles through the phospholipid bilayer; facilitated diffusion moves only water across the phospholipid bilayer.

• Simple diffusion moves particles through the phospholipid bilayer of a cell membrane; facilitated diffusion moves particles through transport proteins.