Page 10 - Q & A STPM 2022 Biology

Biology STPM Chapter 3 Membrane Structure and Transport
Answer : A
The membrane consists of a phospholipid (lecithin) bilayer as well as extrinsic
proteins on the outer and inner surfaces of the membrane and intrinsic
proteins partially embedded in the membrane or penetrate through the
membrane.
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Some of the proteins and phospholipids conjugate with oligosaccharides to
form glycoproteins and glycolipids on the outer surface.
Cholesterol molecules are found between phospholipid molecules.
Semester
1 Question 8
Lipoprotein is present in the cell membrane. This determines the characteristic
of
A the movement of water molecules through xylem.
B the selective permeability towards molecules or ions.
C protein synthesis.
D the diffusion of water molecules and ions.

Answer : B
The membrane consists of phospholipid bilayer and proteins. Hence,
membranes are selectively permeable and regulate the movement of substances
in and out of the cell.

Section B Structured Questions

Question 9
The diagram below shows a section of a cell surface membrane.

T R
S
Q

P

(a) Name the structures labelled P, Q, R, S and T. (5 marks)
(b) Explain how proteins are held in the membrane. (1 mark)
(c) Give two functions of proteins in the membrane. (2 marks)

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Chapter 3.indd 50 11/2/21 9:21 AM