Cell Membrane Structure and Function

What is a primary function of the cell membrane?

• Storing genetic material

• Producing energy for the cell

• Controlling what enters and leaves the cell

• Synthesizing proteins

A cell membrane is described as semi-permeable. What does this mean?

• It allows all substances to pass through freely

• It is completely impermeable to all substances

• It allows some substances to pass through while blocking others

• It only allows water to pass through

What is the main building block of a cell membrane?

• Proteins

• Carbohydrates

• Phospholipids

• Nucleic acids

Which of the following is NOT a major component of a phospholipid?

• Phosphate head

• Glycerol backbone

• Fatty acid tails

• Amino acid chain

What are the water-interacting properties of the phosphate head and fatty acid tails of a phospholipid, respectively?

• Hydrophobic head, hydrophilic tails

• Hydrophilic head, hydrophobic tails

• Both hydrophilic

• Both hydrophobic

Which of the following is NOT a component of a phospholipid?

• Phosphate head

• Glycerol backbone

• Fatty acid tails

• Protein channel

What is a key characteristic of the cell membrane that controls what enters and leaves the cell?

• Fully permeable

• Impermeable

• Semi-permeable

• Selectively active

Which type of molecules can pass through the cell membrane quickly via passive diffusion?

• Large, polar molecules

• Small, nonpolar molecules

• Charged ions

• Large, nonpolar molecules

Why do small, polar molecules like water and ethanol pass through the cell membrane slowly?

• They are too large to fit.

• The hydrophobic interior of the membrane repels them.

• They require active transport.

• They are charged molecules.

Which of the following molecules typically cannot pass through the cell membrane via passive diffusion?

• Oxygen (O2)

• Water (H2O)

• Glucose

• Ethanol