All Free Biology MCQs with Answers

2341. Which of the statement about viruses is incorrect___________________?

• A. We can not grow them in laboratories on artificial medias
• B. They are obligate intracellular parasite.
• C. They can synthesize their nucleic acid
• D. They are resistant to most of antibiotic treatment

Explanation: Viruses do not independently synthesize their nucleic acids because they lack the complete metabolic and protein-synthesis machinery of cells; they replicate using a host cell. They are obligate intracellular parasites and are generally unaffected by antibacterial antibiotics. Students may choose a because viruses can be grown in laboratories, but they require living cells rather than artificial cell-free media.

2342. Protein subunits of capsid is called the capsomeres is a characteristic of each virus. Their number in Herpes virus is__________?

• A. 100
• B. 152
• C. 162
• D. 172Preparing For College Admissions Tests

Explanation: The herpesvirus capsid is an icosahedral structure made of 162 capsomeres. The number is a structural feature of the herpesvirus capsid, not a count of viral genes or particles. Students may choose b because 152 is numerically close and may result from misremembering the standard value.

2343. The name Bacteriophage was coined by____________?

• A. Charles Chamberland
• B. Ivanowski
• C. Twort
• D. D Herelle

Explanation: Felix d'Herelle coined the term bacteriophage for viruses that infect and destroy bacteria. Frederick Twort independently observed bacteriophages earlier, which is why students often confuse him with d'Herelle. Ivanovsky is associated with the discovery of filterable infectious agents later recognized as viruses.

2344. Vaccine Was discovered by______________?

• A. Louis Pasteur
• B. Edward Jennar
• C. Ivanowski
• D. Stanely

Explanation: Edward Jenner developed the first successful vaccine by using material from cowpox lesions to protect against smallpox. Louis Pasteur later developed important vaccines, including those against rabies and anthrax. Students may choose a because Pasteur is strongly associated with the development of modern vaccination, but Jenner made the first vaccine.

2345. Viruses are __________ smaller than bacteria?

• A. 10 - 100 times
• B. 10 - 1000 times
• C. 100 - 1000 times
• D. 1000 - 10000 times

Explanation: Viruses commonly measure about 20 to 300 nm, whereas bacteria are roughly 0.5 to 5 micrometres, or 500 to 5000 nm. Comparing these ranges gives a size difference that can extend from about 10 times to about 1000 times, so option b is the broad textbook range. Students may choose a because it describes the difference for many common virus and bacterium comparisons but is too narrow.

2346. The size of smallest virus is______________?

• A. 10 nm
• B. 20 nm
• C. 30 nm
• D. 40 nm

Explanation: The smallest commonly cited viruses, such as parvoviruses, are approximately 20 nm in diameter. Their very small size reflects their simple structure and dependence on host cells for replication. Students may choose a because some measurements approach 10 nm, but 20 nm is the standard value used in this classification.

2347. The word virus is derived from Latin word venome meaning____________?

• A. Sweet fluid
• B. Sore Fluid
• C. Poisonous Fluid
• D. Salty Fluid

Explanation: The word virus comes from the Latin word meaning poison or poisonous fluid, reflecting the early view that viruses were harmful agents in body fluids. It does not mean sweet, sore or salty fluid. Students may choose b because viral infections can produce sores, but that is a symptom and not the word's etymological meaning.

2348. DNA or RNA of viruses is enclosed in _______________ coat?

• A. Protein
• B. Carbohydrate
• C. Lipid
• D. DNA

Explanation: A virus's genetic material is enclosed in a protein coat called the capsid. The capsid protects the DNA or RNA and helps the virus attach to a host cell. Students may choose lipid because some viruses have a lipid envelope, but that envelope is outside the protein capsid.

2349. Protein coasts of viruses are synthesized in____________?

• A. Lytic cycle
• B. Lysogenic cycle
• C. Both a & b
• D. All of these

Explanation: During the lytic cycle, viral genes direct the host cell to synthesize viral nucleic acid and capsid proteins, assemble new virions and finally lyse the cell. In the lysogenic cycle, the viral genome remains integrated with the host genome and viral coat proteins are generally not produced until induction into the lytic cycle. Students may choose c because both cycles are stages of viral infection, but they do not both actively produce complete viral coats.

2350. Pox viruses are_________?

• A. RNA non-enveloped
• B. RNA enveloped
• C. DNA non-enveloped
• D. DNA enveloped

Explanation: Poxviruses are large double-stranded DNA viruses surrounded by a complex envelope derived from host membranes. Students often choose DNA non-enveloped because DNA viruses are commonly associated with non-enveloped examples, but poxviruses are enveloped.