Which of the following statements best describes the role of cholesterol in the cell membrane?

A. Increases fluidity at high temperatures only

B. Decreases fluidity at both high and low temperatures

C. Increases fluidity at low temperatures and decreases it at high temperatures

D. Decreases fluidity at low temperatures only

Which function is not typically associated with integral proteins in the cell membrane?

A. Enzyme activity

B. Cell signalling

C. Energy storage

D. Transport

What is the primary reason for the amphipathic nature of phospholipids in the cell membrane?

A. To allow integral proteins to function

B. To form a semi-permeable barrier

C. To facilitate cell signalling

D. To enable endocytosis

Peripheral proteins are often involved in which of the following cellular processes?

A. Transport of molecules across the membrane

B. Cell signalling and recognition

C. Formation of the lipid bilayer

D. Active transport using ATP

Which factor primarily contributes to the fluidity of the cell membrane?

A. Presence of cholesterol

B. Number of integral proteins

C. Concentration of extracellular ions

D. Amount of peripheral proteins

a) Explain the amphipathic nature of phospholipids and how this property contributes to the formation of the lipid bilayer in cell membranes. [3]

b) Discuss the role of the lipid bilayer as a semi-permeable barrier, and how this is essential for cellular function. [2]

a) Describe the functions of integral proteins in the cell membrane, providing examples of their roles. [3]

b) Differentiate between integral and peripheral proteins in terms of their position and attachment in the cell membrane. [2]

a) Discuss the importance of membrane fluidity and how it is affected by temperature in animal cells. [3]

b) Explain how cholesterol molecules in the cell membrane contribute to both fluidity and stability. [2]

a) Elaborate on how the amphipathic nature of phospholipids contributes to the self-assembly of the lipid bilayer in cell membranes. [4]

b) Discuss the various functions of peripheral proteins in the cell membrane and provide examples. [3]

c) Explain the implications of membrane fluidity for animal cells at different temperatures, and how cells adapt to these changes. [3]

a) Describe the role of integral proteins in transport and provide examples of different types of transport they facilitate. [4]

b) Discuss how the structure of the cell membrane contributes to its semi-permeable nature. [3]

c) Explain the role of cholesterol in maintaining membrane stability, especially in varying temperature conditions. [3]