Question 1

Which of the following best describes the role of heterotrophic bacteria in the Domain Bacteria?

Accepted Answer

They decompose dead organic matter, recycling nutrients back into the ecosystem.

Question 2

Peptidoglycan is a major component of bacterial cell walls. Which statement about peptidoglycan is correct?

Accepted Answer

It provides structural strength and shape to most bacteria.

Question 3

A student observes a bacterial slide under 1000X magnification and sees spherical cells arranged in clusters. Which term best describes this bacterial shape and arrangement?

Accepted Answer

Coccus in clusters

Question 4

Which equation correctly represents the nitrogen fixation reaction catalyzed by cyanobacteria heterocysts?

Accepted Answer

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

Question 5

Why are heterocysts in cyanobacteria essential for nitrogen fixation?

Accepted Answer

They provide an anaerobic environment necessary for the nitrogenase enzyme to function.

Question 6

Which of the following best explains why Escherichia coli is widely used in biotechnology?

Accepted Answer

It is easy to culture, has a well-understood genome, and can be genetically engineered to produce useful products.

Question 7

A yogurt sample is examined under a microscope and shows long chains of rod-shaped bacteria. Which genus is most likely present?

Accepted Answer

Lactobacillus

Question 8

Which statement about cyanobacteria is correct?

Accepted Answer

They are prokaryotic organisms capable of photosynthesis and are major components of pond scum.

Question 9

Oscillatoria is often found in freshwater environments. What is a distinctive feature of this genus?

Accepted Answer

It forms filamentous colonies that exhibit oscillating movement.

Question 10

Which of the following is a correct application of the Compound Microscope when observing bacteria?

Accepted Answer

Begin with the 40X objective lens to locate and focus, then switch to higher magnification for detailed observation.

Question 11

Which bacterial species is commonly found in the human gut and is a model organism for genetic engineering?

Accepted Answer

Escherichia coli

Question 12

A sample from a pond contains blue-green filaments with visible heterocysts. Which organism is most likely present?

Accepted Answer

Anabaena

Question 13

Which of the following best describes the function of a bacterial capsule?

Accepted Answer

It protects bacteria from desiccation and helps evade host immune responses.

Question 14

Which of the following equations represents the general photosynthetic reaction in cyanobacteria?

Accepted Answer

$\mathrm{6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2}$

Question 15

Which bacterial genus is responsible for producing yogurt and is characterized by rod-shaped cells forming chains?

Accepted Answer

Lactobacillus

Question 16

Which of the following is a plausible reason why cyanobacteria are important in aquatic ecosystems?

Accepted Answer

They are the primary producers, converting solar energy into chemical energy and releasing oxygen.

Question 17

A scientist is studying a bacterial species that can survive in extreme environments and lacks a nucleus. Which domain does this organism most likely belong to?

Accepted Answer

Domain Bacteria

Question 18

Which of the following best explains why antibiotics are less effective against Streptococcus pyogenes in cases of childhood strep throat?

Accepted Answer

Some strains produce toxins and are resistant to certain antibiotics, requiring careful selection of treatment.

Question 19

Which of the following statements about the use of oil immersion in microscopy is correct?

Accepted Answer

Oil immersion is used with the 100X objective lens to increase resolution and clarity at high magnification.

Prokaryotes: Domain Bacteria and Cyanobacteria Lab 13

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