Question 1

Which of the following best describes the significance of Pasteur's swan-neck flask experiment?

Accepted Answer

It disproved spontaneous generation by showing that microbes do not grow in sterilized broth unless exposed to air, supporting biogenesis.

Question 2

Which of the following is NOT a hallmark (minimum requirement) of cellular life?

Accepted Answer

Possession of a protein capsid

Question 3

A patient is diagnosed with tuberculosis. Which staining procedure would be most significant for identifying the causative agent?

Accepted Answer

Acid-fast stain

Question 4

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

Accepted Answer

Both contain nucleic acids, proteins, lipids, and carbohydrates as major polymers.

Question 5

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

Accepted Answer

They do not have a cell membrane and cannot carry out metabolism independently.

Question 6

Which of the following is a beneficial activity of microorganisms in the environment?

Accepted Answer

Decomposing organic matter and recycling nutrients

Question 7

A bacterial cell is placed in a hypertonic solution. What will most likely happen to the cell due to osmosis?

Accepted Answer

Water will move out of the cell, causing it to shrink (plasmolysis).

Question 8

Which of the following statements about Gram-positive and Gram-negative bacteria is CORRECT?

Accepted Answer

Gram-negative bacteria have an outer membrane containing lipopolysaccharide (LPS).

Question 9

Which of the following best describes the function of ribosomes in bacterial cells?

Accepted Answer

Protein synthesis by translating mRNA

Question 10

Which of the following is a correct comparison between light microscopy and electron microscopy?

Accepted Answer

Electron microscopy uses electrons as the source of illumination and achieves higher magnification and resolution.

Question 11

Which of the following best describes the fluid-mosaic model of the plasma membrane?

Accepted Answer

A semi-permeable membrane with proteins embedded in a phospholipid bilayer.

Question 12

Which of the following molecules can most easily pass through the cell membrane without the help of carrier proteins?

Accepted Answer

Small nonpolar molecules such as $$ \mathrm{O}_2 $$ and $$ \mathrm{CO}_2 $$

Question 13

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

Accepted Answer

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

Question 14

Which of the following is an example of a dehydration (synthetic) reaction?

Accepted Answer

Joining two monosaccharides to form a disaccharide with the removal of water: $$ \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 \rightarrow \mathrm{C}_{12}\mathrm{H}_{22}\mathrm{O}_{11} + \mathrm{H}_2\mathrm{O} $$

Question 15

Which of the following is NOT a function of proteins in the cell?

Accepted Answer

Serving as genetic material

Question 16

Which of the following best describes the role of hydrogen bonds in biological molecules?

Accepted Answer

They stabilize the secondary and tertiary structures of proteins and the double helix of DNA.

Question 17

A microbiologist is culturing bacteria on MacConkey agar. Which of the following best describes this medium?

Accepted Answer

It is a selective and differential medium.

Question 18

Which of the following statements about biofilms is TRUE?

Accepted Answer

Biofilms are communities of microorganisms attached to a surface and embedded in a self-produced matrix.

Question 19

Which of the following best describes the process of binary fission in prokaryotes?

Accepted Answer

A process where a single cell divides into two genetically identical daughter cells

Question 20

Which of the following is the correct order of the phases in a typical bacterial growth curve?

Accepted Answer

Lag phase, log (exponential) phase, stationary phase, death phase

MCB2000 Exam ONE Study Guide – Step-by-Step Microbiology Guidance

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