Biology Test Biology Cell Structure & Function 5

Question 1

Which of the following is a key structural difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotes have membrane-bound organelles; prokaryotes lack them

Answer

Eukaryotic cells have a true nucleus and membrane-bound organelles (mitochondria, ER, Golgi), while prokaryotic cells have no membrane-bound compartments and a nucleoid region instead.

Question 2

What is the role of cholesterol in the animal plasma membrane?

Accepted Answer

It stabilizes membrane fluidity across temperature changes

Answer

Cholesterol intercalates between phospholipids, preventing them from packing too tightly at low temperatures and from becoming too fluid at high temperatures, thus buffering membrane fluidity.

Question 3

Which statement about plant cell walls is correct?

Accepted Answer

Primary walls contain cellulose microfibrils embedded in a polysaccharide matrix

Answer

Plant primary cell walls consist of cellulose microfibrils cross-linked by hemicellulose and pectin, providing structural support while allowing flexibility for growth.

Question 4

A researcher observes that a cell has an unusually high number of mitochondria. This cell most likely:

Accepted Answer

Has very high energy demands, such as a cardiac muscle cell

Answer

Cells with high metabolic demands, like cardiac muscle cells, contain densely packed mitochondria to produce sufficient ATP for continuous contraction.

Question 5

Tight junctions between epithelial cells serve mainly to:

Accepted Answer

Prevent leakage of substances through the paracellular space

Answer

Tight junctions (zonula occludens) seal the space between adjacent epithelial cells by fusing their membranes, forcing molecules to pass through cells rather than between them.

Biology Practice Test

Biology Practice Test

Biology Test Biology Cell Structure & Function 5