Question 1

Which of the following statements best explains why Gram-negative bacteria are generally less susceptible to penicillin than Gram-positive bacteria?

Accepted Answer

The outer membrane of Gram-negative bacteria prevents penicillin from reaching its target in the peptidoglycan layer.

Question 2

A scientist isolates a bacterium with the following characteristics: it has a single circular chromosome, no membrane-bound organelles, and a cell wall containing pseudomurein. To which group does this organism most likely belong?

Accepted Answer

Archaea

Question 3

Which structure is primarily responsible for the corkscrew motility observed in spirochetes such as Treponema pallidum?

Accepted Answer

Axial filaments (endoflagella)

Question 4

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome for the cell, and what is the underlying process?

Accepted Answer

The cell will shrink as water leaves the cell by osmosis.

Question 5

Which of the following best describes the function of the bacterial glycocalyx when present as a capsule?

Accepted Answer

It prevents phagocytosis and aids in adherence to surfaces.

Question 6

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

Accepted Answer

Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.

Question 7

A patient is diagnosed with tuberculosis, caused by Mycobacterium tuberculosis. Which cell wall characteristic is most responsible for the acid-fast staining property of this bacterium?

Accepted Answer

Waxy lipid (mycolic acid) bound to peptidoglycan

Question 8

Which of the following best explains why mitochondria and chloroplasts are considered evidence for the endosymbiotic theory?

Accepted Answer

They have circular DNA and 70S ribosomes, similar to bacteria.

Question 9

Which of the following processes requires energy input and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 10

A Gram-negative bacterium is exposed to lysozyme. What is the most likely result, and why?

Accepted Answer

The cell wall is only partially affected because the outer membrane protects the peptidoglycan from lysozyme.

Question 11

Which of the following best describes group translocation in prokaryotic cells?

Accepted Answer

An active process that uses phosphoenolpyruvic acid (PEP) to chemically modify substances as they cross the membrane.

Question 12

Which of the following is a function of the prokaryotic cell wall?

Accepted Answer

It protects the cell from osmotic lysis.

Question 13

A bacterial cell lacking a cell wall is placed in distilled water. What is the most likely outcome, and why?

Accepted Answer

The cell will burst due to osmotic lysis as water enters.

Question 14

Which of the following structures is directly involved in bacterial conjugation and DNA transfer between cells?

Accepted Answer

Conjugation pili

Question 15

Which of the following best describes the arrangement of microtubules in eukaryotic flagella and cilia?

Accepted Answer

A 9+2 array: 9 pairs in a ring plus 2 in the center

Question 16

Which of the following is a unique feature of the plasma membrane in eukaryotic cells compared to prokaryotic cells?

Accepted Answer

Presence of sterols for membrane stability

Question 17

A researcher observes a cell with the following features: paired chromosomes in a nuclear membrane, membrane-bound organelles, and 80S ribosomes. Which type of cell is being observed?

Accepted Answer

Eukaryotic cell

Question 18

Which of the following best explains why some antibiotics, such as streptomycin, specifically target bacterial cells without harming eukaryotic cells?

Accepted Answer

They target the 70S ribosomes found only in bacteria.

Question 19

Which of the following inclusions would most likely be found in a photosynthetic bacterium and is involved in carbon dioxide fixation?

Accepted Answer

Carboxysomes

Question 20

A bacterial cell is exposed to penicillin, which inhibits the formation of peptide cross-bridges in peptidoglycan. What is the most likely effect on the cell?

Accepted Answer

The cell wall will weaken, making the cell susceptible to osmotic lysis.

Functional Anatomy of Prokaryotic and Eukaryotic Cells

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