BIOLOGY FORM 4 - MOVEMENT OF SUBSTANCE ACROSS THE OLASMA MEM

Diagram 1 shows the phospholipid bilayer which forms the plasma membrane.

What are the parts labelled P and Q?

• P : Lipophobic head

  Q: Lipophilic tail

• P : Lipophilic head

  Q: Lipophobic tail

• P : Hydrophilic head

  Q: Hydrophobic tail

• P : Hydrophobic head

  Q: Hydrophilic tail

Diagram 2 shows a structure of plasma membrane.

What is the function of X?

• Act as the barrier to separate the inner and outer part of the cell.

• Help to transport the substances in or out from the cell membrane.

• Stabilise and strengthen the plasma membrane to become more flexible.

• To provide a fixed shape to the cell.

What is X?

• Carrier Protein

• Phospholipid

• Pore protein

• Glycoprotein

Which of the following is the best description about a selectively permeable membrane?

• Only allows water molecules to pass through it.

• Only allows water soluble molecules to pass through it.

• Only allows certain molecules to pass through it

• Only allows certain molecules to pass into the cell but not out of it.

• I and III

• II and IV

• I, II and IV

• I, II, III and IV

Diagram 4 shows the movement of molecules across a plasma membrane by process W.

Which of the following is process W?

• Facilitated diffusion

• Active transport

• Simple diffusion

• Osmosis

Diagram 5 shows an experiment to investigate the movement of water molecules across a selectively permeable membrane from P to Q.

Which of the following is true about the movement of water at the end of the experiment?

• The rate of water molecules diffusing from P to Q is higher than from Q to P.

• The rate of water molecules diffusing from Q to P is higher than P to Q.

• No water molecule diffuses from P to Q.

• The rate of water molecules diffusing from P to Q and from Q to P is the same.

Diagram 6 shows three substances P, Q and R passing through the plasma membrane of a cell.

• A

• B

• C

• D

• I and II only

• II and IV only

• I, II and III only

• I, II, III and IV

Diagram 7 shows an experiment carried out by a group of students.

What is the characteristic shown by L?

• Less permeable

• Semi-permeable

• Non-permeable

• Fully permeable