Set A
The primary barrier of the cell that separates it from its environment is the:
A. Nucleus
B. Plasma membrane
C. Cytoplasm
D. Mitochondria
B. Plasma membrane
Which model best describes the structure of the plasma membrane?
A. Sandwich model
B. Fluid mosaic model
C. Lock-and-key model
D. Lipid raft model
B. Fluid mosaic model
The main structural component forming the bilayer of the cell membrane is:
A. Carbohydrate
B. Protein
C. Phospholipid
D. Nucleic acid
C. Phospholipid
Glycoproteins are composed of:
A. Carbohydrate + Lipid
B. Carbohydrate + Protein
C. Protein + Phospholipid
D. Protein + Cholesterol
B. Carbohydrate + Protein
Which molecules can freely pass through the plasma membrane?
A. Glucose
B. Proteins
C. Oxygen
D. Nucleic acids
C. Oxygen
Cholesterol is considered beneficial because it ______, but harmful because it ______.
A. stabilizes the membrane; clogs arteries
B. strengthens the nucleus; blocks enzymes
C. produces energy; destroys lipids
D. increases permeability; lowers fluidity
A. stabilizes the membrane; clogs arteries
Why is the plasma membrane described as selectively permeable?
A. It blocks all molecules from entering the cell.
B. It only allows fluid to get into and out of the cell.
C. It allows some molecules to pass while restricting others.
D. It allows all substances to pass freely without any resistance.
C. It allows some molecules to pass while restricting others.
What is the main role of carbohydrate chains on the plasma membrane?
A. Energy production
B. Cell-cell recognition
C. Transport of ions
D. Protein synthesis
B. Cell-cell recognition
The presence of double bonds in fatty acids:
A. Makes the membrane rigid
B. Maintains fluidity at low temperatures
C. Blocks all polar molecules
D. Strengthens protein adhesion and cohesion
B. Maintains fluidity at low temperatures
Which statement is correct about membrane permeability?
A. Polar molecules easily pass through.
B. Large molecules move freely across.
C. Small uncharged molecules can diffuse easily.
D. Proteins can pass without assistance.
C. Small uncharged molecules can diffuse easily.
What would happen if cholesterol were removed from the cell membrane?
A. Membrane becomes too fluid or too rigid
B. Membrane permeability improves and develops
C. Membrane stability increases
D. No effect on the cell membrane
A. Membrane becomes too fluid or too rigid
Which membrane protein fastens adjacent animal cells together?
A. Transport protein
B. Adhesion protein
C. Receptor protein
D. Recognition protein
B. Adhesion protein
A hormone that binds only to a specific membrane protein interacts with:
A. Recognition protein
B. Adhesion protein
C. Receptor protein
D. Carrier protein
C. Receptor protein
In type 2 diabetes, cells fail to recognize insulin. Which proteins are malfunctioning?
A. Receptor proteins
B. Adhesion proteins
C. Transport proteins
D. Recognition proteins
A. Receptor proteins
Which molecule requires energy to be transported across the membrane?
A. Oxygen
B. Carbon dioxide
C. Glucose
D. Water
C. Glucose
A membrane component that helps maintain fluidity by preventing it from becoming too rigid or too fluid.
Cholesterol
Flexible extensions used by amoeba for movement are made possible by membrane fluidity.
Pseudopodia
A type of transport protein that forms open pores in the membrane.
Channel protein
A type of fatty acid that makes membranes more rigid at low temperatures.
Saturated fatty acid
Membrane proteins that help in identifying pathogens.
Recognition proteins
Property of the membrane that allows flexibility, fusion, and incorporation of proteins.
Fluidity
Molecule type that, when removed, affects immune recognition of cells.
Carbohydrate chains
General term for molecules like oxygen and carbon dioxide that can freely cross the membrane without assistance.
Small uncharged molecules
Carbohydrate–protein complexes on the membrane surface that function in cell-cell recognition.
Glycoproteins
Proteins in the plasma membrane that bind specifically to hormones or chemical messengers.
Receptor proteins