The genetic material in most bacteria is: MCQ with Answer and Explanation

The genetic material in most bacteria is:
A. Circular DNA
B. Double-stranded RNA
C. Linear DNA
D. Single-stranded RNA
Answer: Option A
Solution (By JKSSB Mock Tests)
Bacteria typically have a single circular double-stranded DNA chromosome located in the nucleoid. They may also have plasmids.

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Practice More Biology Questions

Question #1
Which of the following is a defining feature of prokaryotic cells?
A. Presence of membrane-bound nucleus
B. Presence of 70S ribosomes only
C. Absence of cell wall
D. Linear chromosomes

Correct Answer: Option B


Explanation:
Prokaryotic cells lack a true nucleus; their genetic material is located in a nucleoid region. They possess 70S ribosomes (50S+30S subunits), whereas eukaryotic cells have 80S ribosomes. Prokaryotes generally have a cell wall (except Mycoplasma) and circular DNA, not linear. Membrane-bound organelles like mitochondria, ER are absent. Examples: bacteria and blue-green algae. This distinction is fundamental in cell biology.

This question belongs to: Science Biology
Question #2
The vitamin whose active form, retinol, is essential for vision is:
A. Vitamin E
B. Vitamin A
C. Vitamin C
D. Vitamin D

Correct Answer: Option B


Explanation:
Vitamin A (retinol) is converted to retinal, which combines with opsin to form rhodopsin, the light-sensitive pigment in rod cells of the retina. Deficiency leads to night blindness and xerophthalmia. Carrots and liver are rich sources. Vitamin C is ascorbic acid, D is calciferol, E is tocopherol.

This question belongs to: Science Biology
Question #3
The disease 'osteomalacia' in adults is caused by the deficiency of:
A. Vitamin C
B. Vitamin D
C. Vitamin B₁₂
D. Vitamin A

Correct Answer: Option B


Explanation:
Osteomalacia is the softening of bones in adults due to vitamin D deficiency, leading to inadequate mineralization of bone matrix. In children, the equivalent is rickets. Vitamin D aids calcium absorption. Deficiency may result from poor dietary intake, lack of sunlight, or malabsorption. Bones become weak and prone to fractures.

This question belongs to: Science Biology