Sample Paper 2 Structure

QUESTION :
Diagram shows the movement of substances through the cell membrane .

(a) Give one example of particles that move through P , Q and R.

P :

Q :

R : [ 3 marks]


(b) (i) What is the type of passive transport that occur at Q [1 mark]

ii) State two features of the particle that enables it to pass through the phospholipid bilayers of the cell membrane [2 marks]

(c) Explain why protein molecules are needed in the transportation of certain molecules across the membrane ? [2 marks]

(d) A poisonous substance , cyanide enters the cell . After a while , certain particles could no longer pass through passage R , but passage P and Q are still functional . Explain why. [4 m]

SUGGESTED ANSWER:

a) P : glucose / amino acid
Q : water / carbon dioxide / oxygen / small lipid soluble
particles
R : natrium / potassium ions

b) (i) simple diffusion

(ii) small
soluble to phospholipid bilayers
(c)
to enable large particles to pass through /
to enable particles insoluble to the phopholipid bilayer
to pass through the cell membrane /
to enable particles to move against the concentration gradient

(d) cyanide is a poison that halts aerobic respiration
-No ATP is produced
-Since active transport needs ATP ,

-the transport of substances are also stopped
-For passive transport ,( P and Q ) , it does not need ATP
-therefore the movement of substances still occur.