Cell Membrane Quiz

What is the main component of the cell membrane?

• Phospholipids

• Cholesterol

• Proteins

• Carbohydrates

Answer explanation

The main component of the cell membrane is phospholipids. These molecules form a bilayer, with their hydrophilic heads facing the aqueous environment and their hydrophobic tails facing each other. This structure allows the cell membrane to be selectively permeable, controlling the passage of substances in and out of the cell.

What is the function of the phospholipid bilayer in the cell membrane?

• To stabilize the membrane

• To control what can pass through the membrane

• To transport materials across the membrane

• To identify foreign invaders

Answer explanation

The phospholipid bilayer in the cell membrane serves to control what can pass through the membrane. It acts as a selective barrier, allowing certain molecules and ions to enter or exit the cell while preventing others. This function is crucial for maintaining the cell's internal environment and ensuring proper cellular function.

What is the role of cholesterol in the cell membrane?

• To attract water

• To repel water

• To stabilize the membrane

• To transport materials across the membrane

Answer explanation

Cholesterol plays a crucial role in stabilizing the cell membrane by regulating its fluidity and maintaining its integrity. It is embedded within the membrane's phospholipid bilayer, interacting with the fatty acid chains and preventing them from sticking together. This helps the membrane remain flexible and functional, allowing it to perform its various roles in the cell.

What is the function of proteins in the cell membrane?

• To stabilize the membrane

• To control what can pass through the membrane

• To transport materials across the membrane

• To identify foreign invaders

Answer explanation

Proteins in the cell membrane have several functions, but the correct answer here is that they transport materials across the membrane. This is because they act as channels or pumps, moving substances in or out of the cell. They can transport ions, small molecules, or even larger proteins. This is a crucial function for maintaining the cell's internal environment and allowing it to respond to changes in its external environment.

What is the role of carbohydrates in the cell membrane?

• To stabilize the membrane

• To control what can pass through the membrane

• To transport materials across the membrane

• To identify cell types

Answer explanation

Carbohydrates play a crucial role in the cell membrane by helping to identify cell types. They are attached to proteins and lipids on the outer membrane layer, forming structures that function as identification markers. These markers are recognized by other cells, enabling communication and interaction between them. This is why the correct answer to the question is 'To identify cell types'.

What is the term used to describe the membrane's ability to let some things through but not others?

• Semi-permeable

• Hydrophilic

• Hydrophobic

• Permeable

Answer explanation

The term 'semi-permeable' is used to describe the membrane's ability to let some things through but not others. This means that only certain substances can pass through the membrane, while others are blocked. This is different from 'permeable', which means all substances can pass through, and 'hydrophilic' and 'hydrophobic', which refer to the membrane's affinity for water.