Page 8 - Q & A STPM 2022 Biology

Biology STPM Chapter 3 Membrane Structure and Transport

Question 3
Which of the following factors would tend to increase membrane fluidity?
A A greater proportion of unsaturated phospholipids
B A lower temperature
C A relatively high protein content in the membrane
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D A high membrane protential
Answer : A
Semester
1 The unsaturated fatty acid in the phospholipid molecules have double bonds
which form kinks. This will prevent close packing of the phospholipid
molecules, thereby, increasing fluidity.

Question 4
Which of the following parts of a phospholipid molecule contributes most to
the thickness of a cell surface membrane?
A Phosphate group
B Hydrophilic head
C Glycerol
D Hydrocarbon chain

Answer : D
The phospholipid molecule consists of two fatty acid long chain of hydrocarbon
and a phosphate hydrophilic head.

Phosphate Choline
hydrophilic head
Glycerol
residue

Hydrocarbon
chains

Fatty acids
Phospholipid molecule
Question 5
A cell lacking in oligosaccharides on the external surface of its plasma
membrane would likely be inefficient in
A cell recognition.
B transporting ions against an electrochemical gradient.
C maintaining fluidity of the phospholipid layer.
D establishing a diffusion barrier to charged molecules.

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