Q: A population of bacteria doubles every 30 minutes. If you start with 100 cells, how many cells will there be after 3 hours? Use the formula $$N = N_0$ \times 2$$^{n}$$, where N_0$ is the initial number and n$ is the number of generations.

$$N = 100 \times 2$$^{6}$$ = 6400$$

Question 1

Which structure in prokaryotes is primarily responsible for protecting the cell from bursting in a hypotonic environment, and what is its main chemical component in bacteria?

Accepted Answer

Cell wall; composed mainly of peptidoglycan

Question 2

A scientist isolates a prokaryotic cell with a thick peptidoglycan layer and no outer membrane. Which Gram stain result would you expect, and why?

Accepted Answer

Gram-positive; because the thick peptidoglycan retains the purple dye

Question 3

Which process allows prokaryotes to exchange genetic material through direct cell-to-cell contact, and what structure is essential for this process?

Accepted Answer

Conjugation; sex pilus

Question 4

A bacterium is found to survive in both the presence and absence of oxygen. Which term best describes its metabolic strategy?

Accepted Answer

Facultative anaerobe

Question 5

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

They possess an outer membrane with lipopolysaccharides that impedes antibiotic entry

Question 6

Which metabolic process is carried out by specialized cells called heterocysts in cyanobacteria, and why is this process ecologically important?

Accepted Answer

Nitrogen fixation; it converts atmospheric nitrogen ($$N_2) $$into ammonia ($$NH_3) $$usable by plants

Question 7

During which process does a prokaryote take up external DNA from its environment, resulting in a change in genotype and phenotype?

Accepted Answer

Transformation

Question 8

What is the primary ecological role of chemoautotrophic bacteria in hydrothermal vent communities?

Accepted Answer

They fix inorganic carbon using chemical energy from the oxidation of reduced compounds

Question 9

Which of the following is NOT a mechanism by which prokaryotes increase genetic diversity?

Accepted Answer

Binary fission

Question 10

A researcher observes a prokaryote moving toward a chemical attractant. What term describes this movement, and which structure is most likely involved?

Accepted Answer

Chemotaxis; flagella

Question 11

Which of the following best describes the difference between exotoxins and endotoxins produced by pathogenic bacteria?

Accepted Answer

Exotoxins are secreted and cause disease even if bacteria are not present; endotoxins are released when bacteria die and their cell walls break down

Question 12

Which cell-surface structure in prokaryotes helps them adhere to surfaces and form colonies, but is NOT involved in DNA exchange?

Accepted Answer

Fimbriae

Question 13

A bacterial cell is exposed to a bacteriophage, which transfers DNA from one bacterium to another. What is this process called?

Accepted Answer

Transduction

Question 14

Which of the following best explains why prokaryotes are crucial for plant growth in ecosystems?

Accepted Answer

They increase the availability of nitrogen, phosphorus, and potassium by recycling chemical elements

Question 15

Which of the following statements about plasmids in prokaryotes is correct?

Accepted Answer

Plasmids are smaller rings of DNA outside the main chromosome and can carry genes for antibiotic resistance

Question 16

Which of the following best describes the role of the capsule in pathogenic bacteria?

Accepted Answer

It protects the cell from dehydration and shields pathogenic types from the host immune system

Question 17

A population of bacteria doubles every 30 minutes. If you start with 100 cells, how many cells will there be after 3 hours? Use the formula $$N = N_0$ 	imes 2$$^{n}$$, where N_0$ is the initial number and n$ is the number of generations.

Accepted Answer

$$N = 100 	imes 2$$^{6}$$ = 6400$$

Question 18

Which of the following is a real-world application of prokaryotes in biotechnology?

Accepted Answer

Using E. coli for green cloning in DNA technology

Question 19

Which of the following best describes the evolutionary origin of mitochondria in eukaryotic cells?

Accepted Answer

Mitochondria originated from endosymbiosis of an aerobic prokaryote

Prokaryotes: Bacteria, Archaea, and Protists – Structure, Function, and Diversity

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