Q: A solution has a pH of 4. What is the concentration of hydrogen ions $[H^+]$ in this solution?

$[H^+] = 1 \times 10^{-4} \ \mathrm{M}$

Question 1

Which of the following best describes an opportunistic pathogen?

Accepted Answer

A microbe that causes disease only in a weakened host.

Question 2

Louis Pasteur's experiments with swan-necked flasks provided evidence against which theory?

Accepted Answer

Spontaneous generation

Question 3

According to Koch's postulates, which of the following must be true to establish that a specific microbe causes a specific disease?

Accepted Answer

The microbe must be isolated from a diseased host and grown in pure culture.

Question 4

Which of the following best describes the difference between an observation and a conclusion in the scientific method?

Accepted Answer

An observation is a direct measurement or description, while a conclusion is an interpretation based on observations.

Question 5

A scientist discovers a new microbe that is unicellular, lacks a nucleus, and has a cell wall containing peptidoglycan. To which domain does this organism most likely belong?

Accepted Answer

Bacteria

Question 6

Which of the following is an example of mutualism in the human microbiome?

Accepted Answer

A bacterium in the gut produces vitamin K, which benefits the host, and the host provides nutrients for the bacterium.

Question 7

Which of the following best describes a buffer and its role in biological systems?

Accepted Answer

A buffer is a combination of a weak acid and its conjugate base that helps maintain pH stability.

Question 8

A solution has a pH of 4. What is the concentration of hydrogen ions $[H^+]$ in this solution?

Accepted Answer

$[H^+] = 1 	imes 10^{-4} \ \mathrm{M}$

Question 9

Which of the following statements about dehydration synthesis and hydrolysis is correct?

Accepted Answer

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

Question 10

Which macromolecule is primarily responsible for storing genetic information in cells?

Accepted Answer

Nucleic acids

Question 11

A patient is diagnosed with a bacterial infection. The bacteria are found to be rod-shaped. What is the correct term for this bacterial shape?

Accepted Answer

Bacillus

Question 12

Which of the following best explains why endospores are significant in human health?

Accepted Answer

Endospores allow bacteria to survive harsh conditions, making some infections difficult to eliminate.

Question 13

Which of the following is a correct statement about the difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.

Question 14

Which of the following best describes the function of phospholipids in cell membranes?

Accepted Answer

They form a bilayer that acts as a barrier to protect the cell.

Question 15

A scientist is studying a molecule with the formula $C_6H_{12}O_6$. This molecule is most likely a:

Accepted Answer

Monosaccharide

Question 16

Which of the following is a correct example of a scientific law?

Accepted Answer

A statement that describes a consistent natural phenomenon under specific conditions.

Question 17

Which of the following best describes the role of decomposers in an ecosystem?

Accepted Answer

They break down dead organic matter, recycling nutrients.

Question 18

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 19

Which of the following best explains why protein structure is essential for its function?

Accepted Answer

The sequence of amino acids determines the three-dimensional shape, which is critical for the protein's activity.

Question 20

A researcher finds a microbe that can survive extreme heat and acidity. To which domain does this microbe most likely belong?

Accepted Answer

Archaea

Microbiology Study Notes: Introduction, Biochemistry, and Cell Structure

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