Formative Practice 3.1 (Form 4 Biology Textbook Exercise and Answer)


Question 1:
What are the two main components of the plasma membrane?

Answer:
Proteins and phospholipids


Question 2:
Explain the meaning of fluid mosaic model.

Answer:
The fluid mosaic model refers to protein molecules that are suspended in the phospholipid bilayer forming an ever-changing mosaic pattern. The phospholipid bilayer, proteins and cholesterols are not static but form a dynamic and flexible structure.


Question 3:
Predict what will happen to the plasma membrane if there is no cholesterol.

Answer:
Without cholesterol, the plasma membrane will become too fluid at normal body temperature and may rupture. Without cholesterol, the membrane will become too permeable to dissolved substances.


Question 4:
Explain the role of phospholipid and protein in ensuring the (Accessed on 21 August 2019) permeability of the plasma membrane.

Answer:
The characteristic of phospholipid and protein molecules that only allow passage for a certain number of substances enables or limits the free movement of certain substances though the plasma membrane. This characteristic determines the selective permeability of the plasma membrane.

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