Microbes in Human Welfare Test

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Microbes in Human Welfare Test - 49

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Weekly Quiz Competition

Question 1
1 / -0

A farmer adds Azotobacter culture to soil before sowing maize. Which mineral element will be replenished by doing so?

A
N

B
P

C
K

D
S

Solution

Azotobacter is a free living bacteria in the soil. It helps some cereal crops like maize (Zea mays) in nitrogen fixation. The farmer adds Azotobacter culture to the maize field for enhancing the nitrogen element in the soil by the process of biological nitrogen-fixation.
Thus, the correct answer is 'N.'
Question 2
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Which of the following statements regarding antibiotics is not correct?
(i) Antibiotics are the attenuated microorganisms which in small concentration can kill or retard the growth of other harmful microorganisms.
(ii) Penicillin was the first antibiotic discovered by Alexander Fleming (1928) while working on bacterium Staphylococcus aureus.
(iii) The full potential of penicillin as an effective antibiotic was established by Ernest Chain and Howard Florey.
(iv) Fleming, Chain and Florey were awarded the Nobel Prize in 1945.

A
(i) only

B
(iii) only

C
(ii) and (iv)

D
(i), (iii) and (iv)
Solution
Correct option: A

Explanation:
Antibiotics are antimicrobials that are released by bacteria, fungi or molds naturally or are synthesized artificially that are capable of killing or inhibiting competing microbial species. They are therefore antimicrobial substances and not entire microorganisms.
In 1928 penicillin, the first true antibiotic was discovered by Alexander Fleming from colonies of Staphylococcus bacteria.
However, its full potential as an antibiotic was established by Florey and Chain. Howard Florey,
Ernst Chain, and Sir Alexander Fleming received the Nobel prize for their work on penicillin in 1945.
Thus, the correct answer is '(i) only'.
Question 3
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Select the mismatched pair

A
Symbiotic bacteria - Rhizobium, Frankia

B
Symbiotic cyanobacteria - Frankia, Aulosira

C
Free-living bacteria - Beijerinckia, Azotobacter

D
None of these
Solution
Correct Option: B

Explanation: B
- A symbiotic relationship is formed when two organisms are dependent on each other for survival.
- $$\textit{Frankia}$$ is an example of Gram-positive symbiotic actinobacterium whereas $$\textit{Aulosira}$$ is an example of a free-living cyanobacteria.
$$\textit{Rhizobium}$$ is found in the nodules of leguminous plants whereas $$\textit{Frankia}$$ is found with actinorhizal plants where they form symbiotic relationships. $$\textit{Beijerinckia}$$ and $$\textit{Azotobacter}$$ are found in soil and are free-living bacteria.
Hence, the mismatched pair is Symbiotic cyanobacteria - $$\textit{Frankia}$$ , $$\textit{Aulosira}$$
Question 4
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Bt toxin genes have been expressed in plants in order to provide resistance against
(i) Lepidopterans and fungi
(ii) Animals and bacteria
(iii) Bacteria and fungi
(iv) Coleopterance and dipterans
(v) Lepidopterans

A
(ii) and (iii)

B
(i), (ii) and (iv)

C
(iii) and (v)

D
(iv) and (v).

Solution

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco dudworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause the death of the insect.
So, the correct answer is '(iv) and (v)'.
Question 5
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What causes the inactive form of Bt toxin i.e. protoxin to get converted into its active form in the body of an insect?

A
Temperature of the gut

B
Enzymes present in the saliva

C
Alkaline pH of the gut

D
There is no specific reason

Solution

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is coverted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause death of the insect.
So, the correct answer is 'Alkaline pH of the gut'.
Question 6
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The primary treatment of removal of:

A
dissolved impurities

B
stable particles

C
toxic substances

D
harmful bacteria

Solution

The primary treatment involves physical removal of particles from the sewage through filtration and sedimentation. These are removed initially by sequential filtration which removes the floating debris and then grit is removed by sedimentation.
So, the correct option is 'Option A' .
Question 7
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Which one of the following is not used as biofertiliser?

A
Bacillus thruingiensis

B
Anabaena

C
Nostoc

D
Rhizobium

Solution

Bacillus thuringiensis is not used as a bio-fertitiser but is used to create transgenic plants.
Instead, species of Anabaena, Nostoc, and Rhizobium bacteria are used to improve the fertility of the soil.
Question 8
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Bt toxin kills insect by

A
Inhibiting protein synthesis

B
Generating excessive heat

C
Creating pores in the midgut epithelial cells, leading to cell swelling and lysis

D
Obstructing a biosynthetic pathway

Solution

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause the death of the insect.
So, the correct answer is 'Creating pores in the midgut epithelial cells, leading to cell swelling and lysis.
Question 9
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Microbe used for biocontrol of pest butterfly caterpillars is

A
Saccharomyces cerevisiae

B
Bacillus thuringiensis

C
Streptococcus sp.

D
Trichoderma sp.

Solution

Bacillus thuringiensis , a soil-dwelling bacterium, is the most widely applied species of bacteria used for biological control, used against Lepidopteran, Coleopteran and Dipteran.
So, the correct answer is 'Bacillus thuringiensis'
Question 10
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Bacillus thuringiensis forms protein crystals which contain insecticidal protein. This protein

A
Binds with epithelial cells of mid gut of the insect pest ultimately killing it

B
Is activated by acidic pH of the gut of the insect pest

C
Does not kill the carrier bacterium which is itself resistant to this toxin

D
All of the above
Solution
Correct Option: A
Explanation:
- $$Bacillus$$ $$thuringiensis$$ produce endotoxin proteins that kill certain insects.
- These proteins form crystalline deposits in bacterial spores and are called crystalline proteins or cry proteins.
- The cry protein is not toxic to the bacterium because it exists in an inactive protoxin form, inside the gut.
- Due to the alkaline medium, the inactive protoxin is activated into toxin form that binds to the epithelial cells of the midgut and makes the surface porous.
- This causes swelling and lysis of the gut wall leading to the death of insects.
Hence, this protein binds with epithelial cells of the midgut of the insect pest ultimately killing it.

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Microbes in Human Welfare Test - 49

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Microbes in Human Welfare Test - 49

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SHARING IS CARING

Question 1

N

P

K

S

Solution

Question 2

(i) only

(iii) only

(ii) and (iv)

(i), (iii) and (iv)

Solution

Question 3

Symbiotic bacteria - Rhizobium, Frankia

Symbiotic cyanobacteria - Frankia, Aulosira

Free-living bacteria - Beijerinckia, Azotobacter

None of these

Solution

Question 4

(ii) and (iii)

(i), (ii) and (iv)

(iii) and (v)

(iv) and (v).

Solution

Question 5

Temperature of the gut

Enzymes present in the saliva

Alkaline pH of the gut

There is no specific reason

Solution

Question 6

dissolved impurities

stable particles

toxic substances

harmful bacteria

Solution

Question 7

Bacillus thruingiensis

Anabaena

Nostoc

Rhizobium

Solution

Question 8

Inhibiting protein synthesis

Generating excessive heat

Creating pores in the midgut epithelial cells, leading to cell swelling and lysis

Obstructing a biosynthetic pathway

Solution

Question 9

Saccharomyces cerevisiae

Bacillus thuringiensis

Streptococcus sp.

Trichoderma sp.

Solution

Question 10

Binds with epithelial cells of mid gut of the insect pest ultimately killing it

Is activated by acidic pH of the gut of the insect pest

Does not kill the carrier bacterium which is itself resistant to this toxin

All of the above

Solution

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