Topic 4 Crossing the plasma membrane

What is the primary function of the plasma membrane in a cell?

• To provide structural support

• To regulate the movement of substances in and out of the cell

• To store genetic information

• To produce energy

Which process involves the movement of water across a semi-permeable membrane?

• Diffusion

• Osmosis

• Active transport

• Filtration

What is the role of protein channels in the plasma membrane?

• To synthesise proteins

• To facilitate the transport of specific molecules across the membrane

• To provide energy for the cell

• To store nutrients

Which of the following best describes a concentration gradient?

• A uniform distribution of particles

• A difference in the concentration of a substance across a space

• A random movement of particles

• A chemical reaction

In which type of solution does a cell swell due to water intake?

• Isotonic

• Hypertonic

• Hypotonic

• Supersonic

What happens to a cell placed in a hypertonic solution?

• It swells

• It shrinks

• It remains the same

• It bursts

Which of the following is a characteristic of diffusion?

• Requires energy

• Moves substances against their concentration gradient

• Moves substances from high to low concentration

• Involves only water molecules

What is the main component of the phospholipid bilayer?

• Proteins

• Carbohydrates

• Phospholipids

• Nucleic acids

Which of the following processes requires energy input from the cell?

• Diffusion

• Osmosis

• Active transport

• Facilitated diffusion

What is the effect of a hypotonic solution on plant cells?

• Causes wilting

• Causes turgidity

• Causes plasmolysis

• Causes cell death