$[H^+] = 1 \times 10^{-3} \ \mathrm{mol/L}$

Question 1

Which of the following best describes Koch's postulates and their significance in microbiology?

Accepted Answer

They are a set of criteria used to establish a causative relationship between a microbe and a disease.

Question 2

Which of the following statements about prokaryotic and eukaryotic cells is correct?

Accepted Answer

Prokaryotic cells lack a membrane-bound nucleus, while eukaryotic cells have a membrane-bound nucleus.

Question 3

A solution has a pH of 3. What is the concentration of hydrogen ions $[H^+]$ in this solution?

Accepted Answer

$[H^+] = 1 	imes 10^{-3} \ \mathrm{mol/L}$

Question 4

Which of the following best explains the difference between dehydration synthesis and hydrolysis reactions?

Accepted Answer

Dehydration synthesis joins monomers by removing water, while hydrolysis breaks polymers by adding water.

Question 5

A patient is diagnosed with a bacterial infection. According to Koch's postulates, which step would confirm that the bacteria cause the disease?

Accepted Answer

The bacteria must be isolated from the diseased host and grown in pure culture, then cause the same disease when introduced into a healthy host.

Question 6

Which of the following is NOT a function of the bacterial cell wall?

Accepted Answer

It synthesizes ATP for the cell.

Question 7

Which of the following best describes an opportunistic pathogen?

Accepted Answer

A microbe that causes disease only when the host's defenses are compromised.

Question 8

Which of the following is a correct statement about the structure of prokaryotic flagella?

Accepted Answer

Prokaryotic flagella are composed of flagellin and rotate like a propeller.

Question 9

Which of the following best explains the difference between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Question 10

Which of the following is a biologically important macromolecule and its correct monomer?

Accepted Answer

Protein – amino acid

Question 11

A scientist wants to make 100 mL of a 0.5 M NaCl solution. How many moles of NaCl are needed?

Accepted Answer

$0.05 \ \mathrm{mol}$

Question 12

Which of the following best describes the function of ATP in the cell?

Accepted Answer

ATP stores and transfers energy for cellular processes.

Question 13

Which of the following is a correct example of a chemical bond and its description?

Accepted Answer

Covalent bond: sharing of electron pairs between atoms

Question 14

Which of the following best explains why viruses are not classified as living organisms?

Accepted Answer

Viruses cannot carry out metabolism or reproduce independently.

Question 15

Which of the following is a correct statement about the endosymbiotic theory?

Accepted Answer

It proposes that mitochondria and chloroplasts originated from free-living prokaryotes engulfed by ancestral eukaryotic cells.

Question 16

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

Water will leave the cell, causing it to shrink (plasmolysis).

Question 17

Which of the following is a correct match between a eukaryotic organelle and its function?

Accepted Answer

Golgi apparatus – modification and packaging of proteins

Question 18

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element consists of only one type of atom, while a compound consists of two or more different elements chemically bonded.

Question 19

Which of the following is a correct description of a biofilm?

Accepted Answer

A complex community of microorganisms attached to a surface and embedded in a self-produced matrix.

Question 20

Which of the following best explains why antibiotics are less effective against bacteria in biofilms?

Accepted Answer

The extracellular matrix and close proximity of cells in biofilms protect bacteria from antibiotics.

Microbiology Exam Study Guide: Chapters 1–3 (Introduction, Chemistry of Biology, Prokaryotic Cells, Eukaryotes)

Study Guide - Practice Questions