Plasma Membrane Structure Quiz

What is the primary reason plasma membranes are described as a fluid mosaic model?

• They consist of a variety of molecules that can move laterally.

• They are rigid and do not allow movement.

• They are impermeable to all substances.

• They are composed of a single type of molecule.

Which of the following is NOT a component of the fluid mosaic model?

• Phospholipids

• Nucleic acids

• Proteins

• Cholesterol

In the phospholipid bilayer, what is the orientation of the hydrophilic heads?

• Randomly oriented

• Facing the outside of the bilayer

• Facing each other

• Facing the inside of the bilayer

What is the main function of cholesterol in the plasma membrane?

• To increase membrane fluidity at high temperatures

• To decrease membrane fluidity at high temperatures

• To transport ions across the membrane

• To act as a receptor for hormones

What happens to the membrane if it becomes too fluid at high temperatures?

• It becomes more rigid

• It becomes less permeable to all substances

• It remains unchanged

• It becomes more permeable to water and ions

Which type of protein spans the entire width of the membrane?

• Lipid-anchored protein

• Glycoprotein

• Integral protein

• Peripheral protein

What is the role of glycoproteins in the plasma membrane?

• To act as channels for ions

• To increase membrane fluidity

• To provide structural support

• To serve as receptors for cell recognition

How do carrier proteins transport molecules across the membrane?

• By acting as a barrier to molecules

• By increasing the membrane's fluidity

• By binding to molecules and changing shape

• By forming a channel for molecules to pass through

Which molecules can diffuse through the phospholipid bilayer by simple diffusion?

• Large polar molecules

• Lipid-soluble molecules

• Ions like sodium

• Proteins

What characteristic of the phospholipid bilayer allows it to be partially permeable?

• The presence of cholesterol

• The arrangement of hydrophilic heads and hydrophobic tails

• The presence of integral proteins

• The thickness of the bilayer