Question 1

Which of the following statements best explains why prokaryotes are essential for nutrient cycling in ecosystems?

Accepted Answer

Prokaryotes decompose organic matter and recycle nutrients, making them available for other organisms.

Question 2

A scientist isolates a unicellular organism with a cell wall containing peptidoglycan, no membrane-bound organelles, and a single circular DNA molecule. To which kingdom does this organism most likely belong?

Accepted Answer

Eubacteria

Question 3

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

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and stain purple, while Gram-negative bacteria have a thin peptidoglycan layer and an outer lipid membrane, staining pink.

Question 4

Which bacterial structure is responsible for the exchange of genetic material during conjugation?

Accepted Answer

Pilus

Question 5

A bacterium is found living in the human gut, where it can survive with or without oxygen. How would you classify its respiration?

Accepted Answer

Facultative anaerobe

Question 6

Which of the following is a real-world example of a beneficial use of bacteria in industry?

Accepted Answer

Producing insulin for diabetes treatment

Question 7

A chain of round bacteria is observed under a microscope. What is the correct term for this arrangement?

Accepted Answer

Streptococcus

Question 8

Which of the following equations correctly represents the process of nitrogen fixation by bacteria?

Accepted Answer

$$\mathrm{N_2$ + 8H^+ + 8e^- + 16ATP \rightarrow 2NH_3 + H_2$ + 16ADP + 16P_i}$$

Question 9

Which feature is unique to Archaebacteria compared to Eubacteria?

Accepted Answer

Ability to live in extreme environments such as hot springs and salt lakes

Question 10

Which of the following best describes the role of photosynthetic bacteria in marine ecosystems?

Accepted Answer

They are major producers of atmospheric oxygen.

Question 11

A patient is diagnosed with a bacterial infection. The bacteria stain pink with Gram stain. Which of the following is most likely true about these bacteria?

Accepted Answer

They have a thin peptidoglycan layer and an outer lipid membrane.

Question 12

Which of the following is NOT a function of the bacterial capsule?

Accepted Answer

Protein synthesis

Question 13

Which of the following best explains why some bacteria are used in the production of yogurt and cheese?

Accepted Answer

They produce lactic acid through fermentation, which helps in the coagulation of milk proteins.

Question 14

Which of the following is a correct pairing of bacterial shape and arrangement?

Accepted Answer

Diplococcus: pairs of round bacteria

Question 15

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids are small loops of DNA that often carry genes for antibiotic resistance.

Question 16

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

Accepted Answer

A form of asexual reproduction where the cell divides into two genetically identical cells.

Question 17

Which of the following is a plausible reason why Gram-negative bacteria are often more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

Their outer lipid membrane acts as a barrier to many antibiotics.

Question 18

Which of the following is a correct description of the role of ribosomes in bacterial cells?

Accepted Answer

Ribosomes are responsible for protein synthesis.

Question 19

Which of the following best explains why some bacteria are considered pathogens?

Accepted Answer

They cause diseases in humans and other organisms by invading tissues or producing toxins.

Question 20

Which of the following is a real-world example of how bacteria benefit human health?

Accepted Answer

Bacteria in the intestines produce vitamins K and B12, which are essential for human health.

L5a Biodiversity

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