Free Biodiversity and Variety of Life MCQs with Answers

301. Virus attacks and hijacks host's _.

• A. Mitochondria
• B. Nucleus
• C. Ribosomes
• D. Endoplasmic reticulum

Explanation: The correct answer is C) Ribosomes, as many viruses hijack the host cell's ribosomes to produce viral proteins required for the replication and assembly of new viral particles.

302. It is anti-viral:

• A. Penicillin
• B. Streptomycin
• C. Tetracycline
• D. Interferon

Explanation: The correct answer is D) Interferon, as it is an antiviral protein produced by the body's immune system to combat viral infections.

303. _ is the second major form of hepatitis.

• A. Hapatitis A
• B. Hepatitis B
• C. Hepatitis C
• D. Hepatitis D

Explanation: The correct answer is B) Hepatitis B, as it is the second major form of hepatitis caused by the Hepatitis B virus (HBV).

304. Which structure is involved in the transfer of genetic material from one bacterium to another?

• A. Flagella
• B. Pilli
• C. Cytoplasm
• D. Mesosomes

Explanation: The correct answer is B) Pili, as they are the structures involved in the transfer of genetic material from one bacterium to another during conjugation.

305. Salmonella typhi exhibits which shape?

• A. Spherical
• B. Spiral
• C. Rod-shape
• D. Comma-shape

Explanation: The correct answer is C) Rod-shape, as Salmonella typhi exhibits a rod-shaped morphology.

306. All of the following bacteria have definite shapes except:

• A. Clostridium tetani
• B. Spirillum
• C. Salmonella typhi
• D. Mycoplasma

Explanation: Mycoplasma is a type of bacteria that lacks a rigid cell wall. As a result, it doesn't have a definite shape like other bacteria. This group of bacteria is often referred to as "pleomorphic," meaning they can take on various shapes or sizes, ranging from spherical to filamentous. The absence of a cell wall is a unique feature of Mycoplasma, which distinguishes it from other bacteria.

307. Antibiotics that kill microbes immediately are called _.

• A. Microbistatic
• B. Biostatic
• C. Microbicidal
• D. Chemotherapeutic

Explanation: Microbicidal accurately describes antibiotics that directly and immediately kill microbes, while the other options refer to different modes of microbial control without immediate killing.

308. Mesosomes are infoldings of the cell membrane and are involved in:

• A. DNA replication
• B. Protein synthesis
• C. RNA synthesis
• D. Metabolism

Explanation: Mesosomes are the areas in the cell membrane of prokaryotic cell which fold inwards. It helps in cell wall formation, DNA replication, respiration and increases the surface area of the plasma membrane.

309. Which statement about bacteria is true:

• A. Gram-positive bacteria have more lipids in their cell wall
• B. Gram-negative bacteria have more lipids in their cell wall
• C. Lipids are absent in the cell wall of both gram-positive and negative bacteria
• D. Both have an equal amount of lipids

Explanation: The key difference in the cell walls of gram-positive and gram-negative bacteria is the presence of an outer membrane in gram-negative bacteria, which contains lipids and contributes to their overall structure and properties.

310. RNA viruses appear to have higher rates of mutation because:

• A. RNA nucleotides are more unstable than DNA nucleotides
• B. Replication of their nucleic acid does not involve the proofreading steps of DNA replication
• C. RNA viruses replicate faster
• D. RNA viruses respond more to mutagens

Explanation: The primary reason for the higher mutation rate in RNA viruses is that their replication process lacks the proofreading mechanisms that are present in DNA replication. DNA replication includes proofreading and error-correcting mechanisms that help maintain the accuracy of the genetic code. RNA viruses, on the other hand, use RNA-dependent RNA polymerases (enzymes responsible for copying RNA) that lack the ability to correct errors. As a result, mistakes made during replication are more likely to become permanent mutations in the viral genome.