AP-Micro (Microbiology) Cell Structure and Function

Question 1

Which component is unique to prokaryotic cells and helps maintain their shape and protect against osmotic pressure?

Accepted Answer

Cell Wall

Answer

The cell wall is a rigid outer layer found in prokaryotic cells (bacteria and archaea) that provides structural support and protection. It helps maintain the cell's shape and prevents osmotic lysis, especially when the cell is in a hypotonic environment. Eukaryotic cells like animal cells lack a cell wall, while plant and fungal cells have different types of cell walls.

Question 2

What structure in a bacterial cell is responsible for motility?

Accepted Answer

Flagellum

Answer

The flagellum (plural: flagella) is a whip-like appendage found on the surface of many bacterial cells. It rotates like a propeller, enabling the bacterium to move through liquid environments, a process known as motility. Pili are involved in attachment and genetic exchange, while ribosomes are for protein synthesis and capsules for protection.

Question 3

Which of the following is found in both prokaryotic and eukaryotic cells?

Accepted Answer

Ribosomes

Answer

Ribosomes are essential cellular organelles responsible for protein synthesis (translation) and are found in all known forms of life, including both prokaryotic and eukaryotic cells. While their structure differs slightly between the two cell types (prokaryotic ribosomes are smaller), their fundamental function is conserved. Nucleus, Golgi apparatus, and mitochondria are membrane-bound organelles unique to eukaryotes.

Question 4

What is the primary function of the bacterial capsule?

Accepted Answer

Protection against phagocytosis

Answer

The bacterial capsule is an outer, often sticky, layer composed of polysaccharides or polypeptides. Its primary function is to protect the bacterium from phagocytosis by host immune cells, making it more virulent. It can also aid in adherence to surfaces and prevent desiccation.

Question 5

Which of the following structures allows bacteria to exchange genetic material?

Accepted Answer

Pilus

Answer

Pili (specifically sex pili) are hair-like appendages on the surface of bacterial cells that play a crucial role in bacterial conjugation. They form a bridge between donor and recipient cells, allowing for the direct transfer of genetic material, typically plasmids, from one bacterium to another. This process contributes to genetic diversity and the spread of traits like antibiotic resistance.

AP Practice Test

AP Practice Test

AP-Micro (Microbiology) Cell Structure and Function