Question

Which among the following are the smallest living cells, known without a definite cell wall, pathogenic to plants as well as animals, and can survive without oxygen?

• A. Bacillus
• B. Pseudomonas
• C. Mycoplasma
• D. Nostoc

Answer 1

The correct option is C

Mycoplasma

The correct option is C.

Explanation of the correct option:

1. Mycoplasma is included in class mollicutes.
2. They are primitive organisms lacking cell walls.
3. As they do not have a cell wall, they show great antibiotic resistance.
4. And can be parasitic as well as saprophytic in nature.
5. They are responsible for many respiratory disorders.

Explanation of the incorrect options:

Option A:

1. Bacillus is a gram-positive, aerobic bacteria that contain a cell membrane and cell wall as well.
2. They also can be pathogenic.

Option B:

1. Pseudomonas is also a pathogenic bacteria.
2. But it is a Gram-negative bacteria with a cell wall and cell membrane.

Option D:

1. Nostoc is a blue-green Algae helping plants with nitrogen fixation.
2. It has a definite cell wall.
3. And it is not pathogenic in nature.

Final answer: Mycoplasma is the smallest living cell, known without a definite cell wall, pathogenic to plants as well as animals, and can survive without oxygen.