Question 1

Which of the following statements best describes the Cell Theory?

Accepted Answer

All living organisms are composed of one or more cells, and all cells arise from pre-existing cells.

Question 2

A scientist wants to observe the surface structure of a virus particle. Which microscope should they use, and what is its approximate resolution limit?

Accepted Answer

Scanning Electron Microscope; $$\sim 10 nm$$

Question 3

Which organelle is responsible for energy production in eukaryotic cells, and why do muscle cells contain more of them?

Accepted Answer

Mitochondria; because muscle cells require more ATP for contraction

Question 4

Which of the following best explains why the plasma membrane forms a bilayer?

Accepted Answer

Phospholipids have hydrophilic heads and hydrophobic tails, causing them to arrange in a bilayer to shield tails from water.

Question 5

Which of the following is a unique property of facilitated diffusion across a cell membrane?

Accepted Answer

It requires specific transport proteins but does not require energy.

Question 6

Which of the following correctly matches the organelle with its function and presence in cell types?

Accepted Answer

Ribosomes: protein synthesis; found in both prokaryotes and eukaryotes

Question 7

Which of the following best describes the structure of DNA in prokaryotes compared to eukaryotes?

Accepted Answer

Prokaryotes have a single, circular chromosome; eukaryotes have multiple, linear chromosomes.

Question 8

Which of the following is NOT a component of a nucleotide in DNA?

Accepted Answer

A fatty acid

Question 9

According to Chargaff’s rule, which of the following is true for double-stranded DNA?

Accepted Answer

$$\%A = \%T$$ and $$\%G = \%C$$

Question 10

Which of the following best describes the directionality (polarity) of a DNA strand?

Accepted Answer

It has a 5' phosphate end and a 3' hydroxyl end.

Question 11

Which of the following is a post-transcriptional modification found in eukaryotes but not in prokaryotes?

Accepted Answer

Addition of a 5' cap to mRNA

Question 12

A mutation that changes a single nucleotide but does not alter the amino acid sequence of a protein is called:

Accepted Answer

A silent mutation

Question 13

Which of the following best describes an operon and its main benefit in prokaryotes?

Accepted Answer

A cluster of genes under the control of a single promoter, allowing coordinated expression of related genes.

Question 14

Which of the following best describes a chemoautotroph?

Accepted Answer

An organism that uses inorganic chemicals for energy and $$CO_2 as a $$carbon source.

Question 15

In a thioglycolate tube, where would you expect to find obligate anaerobes growing?

Accepted Answer

At the bottom of the tube, where oxygen concentration is lowest.

Question 16

Why is oxygen potentially dangerous to some microorganisms in high amounts?

Accepted Answer

It can form reactive oxygen species that damage cellular components.

Question 17

Which type of culture medium would you use to distinguish between two bacterial species based on their metabolic properties?

Accepted Answer

Differential medium

Question 18

During which phase of the bacterial growth curve does the population size remain constant as the rate of cell division equals the rate of cell death?

Accepted Answer

Stationary phase

Question 19

If a bacterial culture starts with 100 cells and doubles every 30 minutes, how many cells will there be after 2 hours? Use the formula $$N = N_0$ 	imes 2^n$$, where $$n is $$the number of generations.

Accepted Answer

$$N = 100 	imes 2^4$ = 1600$$ cells

Question 20

Which of the following is a direct method for quantifying bacteria that requires incubation?

Accepted Answer

Plate count method

Microbiology Exam 2 Review – Step-by-Step Study Guidance

Study Guide - Practice Questions

Study Guide - Flashcards