Biology

Which substance can move freely across the phospholipid bilayer of the plasma membrane?

• A. Glucose

• B. Amino acids

• C. Glycerol

• D. Ions

Which process involves the movement of water molecules through a selectively permeable membrane down a concentration gradient?

• A. Diffusion

• B. Osmosis

• C. Facilitated diffusion

• D. Active transport

Diagram 1 shows a model of the plasma membrane. The part labelled X is known as a ...............

• A. carrier protein

• B. channel protein

• C. phospholipid

• D. cholesterol

Diagram 2 shows the movement of ion X⁺ across the plasma membrane. WHich process transports ion X⁺ across the plasma membrane?

• A. Osmosis

• B. Facilitated diffusion

• C. Simple diffusion

• D. Active transport

Which of the following processes is affected by the presence of a metabolic poison?

• A. Absorption of water by root hair cells

• B. Uptake of iodine by algae living in the sea

• C. Absorption of digested food in the small intestine

• D. Movement of amino acids across the plasma membrane

Which cell component is present in large numbers in a cell that transports substances through active transport?

• A. Robosome

• B. Nucleus

• C. Mitochondrion

• D. Golgi apparatus

Which of the above events are related to the process of facilitated diffusion?

• A. P and Q

• B. P and S

• C. Q and R

• D. Q, R and S

Potatp strips of equal lengths were placed in sucrose solutions of different concentrations. Which graph shows the correct percentage change in the mass of the potato strips against the concentration of sucrose solution?

x-axis : concentration of sucrose solution

y-axis : mass of potato strip

• A

• B

• C

• D

Diagram 3 shows an experiment set-up to investigate osmosis. The Visking tubing and beaker in Diagram 3 are filled with solutions X and Y respectively.

• A

• B

• C

• D

An experiment was carried out using potato strips of equal length immersed in different concentrations of sucrose solutions. The lengths of the potato strips were measured at regular intervals. Which graph shows the results of the potato strip that was immersed in the weakest sucrose solution?

• A

• B

• C

• D