Page 18 - Q & A STPM 2022 Biology

Biology STPM Chapter 3 Membrane Structure and Transport
Answer : C
The phospholipid bilayer is not permeable to charged ions such as Na , K ,
+
+
Cl , HCO and hydrophilic molecules such as glucose and macromolecules.
–
–
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Question 9
The diagram below shows the movement of three substances P, Q and R into
a cell through the cell surface membrane.
P Q R
Semester
1

Which of the following are P, Q and R?
P Q R
A Ethanol Oxygen Amino acid
B Carbon dioxide Acetone Amino acid
C Acetone Glucose Oxygen
D HCO – Oxygen Glucose
3

Answer : D
The phospholipid bilayer is permeable to very small, uncharged polar
molecules like oxygen and carbon dioxide, and hydrophobic molecules such
–
+
as steroids. Hydrophilic substances such as Na , HCO , ions, water molecules
3
diffuse across the membranes with the help of transport proteins.
Question 10
Which of the following does not involve facilitated diffusion?
A Movement of sodium ions across the membrane of axon during action
potential.
B Transportation of glucose into the cell.
C Diffusion of ATP from the mitochondrion.
D Movement of oxygen and carbon dioxide across the membrane of the
alveolus.

Answer : D
Small molecules such as oxygen and carbon dioxide diffuse through the
phospholipid bilayer.

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Chapter 3.indd 58 11/2/21 9:21 AM