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Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

In Nostoc, the enzyme nitrogenase occurs in

  1. Vegetative cells

  2. Heterocysts

  3. Only in hormogones

  4. Both A and B
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Nostoc is a cyanobacteria. It has ability to fix atmospheric nitrogen. It converts nitrogen into ammonia. The heterocysts present in it are specialized cyanobacterial cells for nitrogen fixation. It contains enzyme nitrogenase. Nitrogenase is inactivated by oxygen. Hence, the heterocyst creates a micro anaerobic environment.
Thus, the correct answer is 'Heterocysts.'
Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

The similarity between cyanobacterium and bacterium is

  1. Presence of flagella

  2. Presence of 80S ribosome

  3. Presence of nucleoid

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There are many similarities between cyanobacterium and bacterium. They both posses saparophytic mode of life. They both lack true cell organelles. They both posses nucleoid instead of true nucleus. 

Thus, the correct answer is 'Presence of nucleoid.'

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Pigment containing membranous extensions in some cyanobacteria are

  1. Chromatophores

  2. Heterocysts

  3. Basal bodies

  4. Penumatophores
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In cyanobacteria, the pigment-containing membranous extensions that facilitate photosynthesis are called chromatophores (or thylakoids). Heterocysts are specialized cells for nitrogen fixation, not pigment storage.

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Members of which algal class impart red colour to red sea?

  1. Cyanophyceae

  2. Rhodophyceae

  3. Phaeophyceae

  4. Bacillariophyceae
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The red sea is the saltiest sea and connects to the ocean without any river meeting the sea. It is named so because of the abundant occurrence of red coloured planktonic cyanophyceae called Trichodesmium erythraeum. This cyanophyceae imparts red colour to red sea. This results in the algal bloom or red bloom.

Thus, the correct answer is 'Cyanophyceae.'

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

I. Unicellular, colonial, filamentous, marine or terrestrial forms.
II. The colonies are surrounded by a gelatinous sheath.
III. Some can fix atmospheric nitrogen in specialized cells called heterocysts.
IV. They often form blooms in water bodies.
These above characters are seen in

  1. Archaebacteria

  2. Cyanobacteria

  3. Chrysophytes

  4. Dinoflagellates

  5. Slime Moulds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cyanobacteria are also called as Blue green algae. They are unicellular, colonial, filamentous prokaryotes. They are found in marine and terrestrial habitats. The colonies are surrounded by a gelatinous sheath. They are photosynthetic bacteria. They often form blooms in water bodies and results in eutrophication. Some Cyanobacteria like Nostoc can fix atmospheric nitrogen in specialized cells called heterocysts and make it available to plants.

Thus, the correct answer is 'Cyanobacteria.'

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Azolla possesses symbiotic association with

  1. <p>Anabaena</p>

  2. <p>Nostoc</p>

  3. <p>Azospirillum</p>

  4. <p>Rhizobium</p>
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Azolla is a small aquatic fern that maintains a symbiotic relationship with the cyanobacterium Anabaena azollae. This bacterium lives in the leaf cavities of the fern and fixes nitrogen for the plant.