Consider statements about microorganisms: 1. Bacteria can be beneficial or harmful. 2. Fungi are used in food production. 3. Viruses are living outside a host. Which are correct? MCQ with Answer and Explanation

Consider statements about microorganisms: 1. Bacteria can be beneficial or harmful. 2. Fungi are used in food production. 3. Viruses are living outside a host. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Answer: Option D
Solution (By JKSSB Mock Tests)
Bacteria exhibit diverse roles; many are beneficial (e.g., gut flora, nitrogen fixers, decomposers), while some are pathogenic and cause diseases. Fungi are extensively used in food production, such as yeast (Saccharomyces) in baking and brewing, and molds (Penicillium) in cheese making (e.g., Roquefort, Camembert). Viruses are considered non-living outside a host cell because they lack metabolic machinery and cannot replicate independently; they only exhibit living characteristics when inside a host. Thus, statements 1 and 2 are correct.

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Practice More Biology Questions

Question #1
The bacterium used in the production of Swiss cheese (for holes) is:
A. Penicillium roqueforti
B. Lactobacillus acidophilus
C. Propionibacterium shermanii
D. Streptococcus thermophilus

Correct Answer: Option C


Explanation:
Propionibacterium shermanii ferments lactate to propionic acid, acetic acid, and CO₂ during cheese ripening; the CO₂ forms the characteristic holes (eyes) in Swiss cheese. Lactobacillus and Streptococcus are starter cultures for acid production, Penicillium roqueforti is used for blue cheese.

This question belongs to: Science Biology
Question #2
The pigment that is essential for vision in low light is:
A. Rhodopsin
B. Melanin
C. Iodopsin
D. Hemoglobin

Correct Answer: Option A


Explanation:
Rhodopsin (visual purple) in rod cells of the retina consists of opsin and retinal (derived from vitamin A). It bleaches in light, triggering nerve impulses. It is highly sensitive, enabling night vision. Iodopsin is in cones for color vision.

This question belongs to: Science Biology
Question #3
The human disease characterized by the formation of amyloid plaques in the brain is:
A. Epilepsy
B. Multiple sclerosis
C. Parkinson's disease
D. Alzheimer's disease

Correct Answer: Option D


Explanation:
Alzheimer's disease is a progressive neurodegenerative disorder marked by extracellular amyloid-beta plaques and intracellular neurofibrillary tangles of tau protein, leading to memory loss and cognitive decline. Parkinson's involves dopamine neuron loss, multiple sclerosis demyelination, epilepsy seizures.

This question belongs to: Science Biology