All Free Biology MCQs with Answers

2301. Viruses resemble living things because they: _____________?

• A. Circulate
• B. Move
• C. Reproduce
• D. Are crystalline

Explanation: Viruses resemble living organisms because they can reproduce inside a suitable host cell using the host's machinery. They are not independently cellular and cannot reproduce on their own outside a host. Students may choose crystallization because viruses can form crystals, but crystallization is a non-living characteristic rather than evidence of life.

2302. All of the following diseases caused by Viruses Except: ____________?

• A. Poliomyelitis
• B. Common cold
• C. Yellow fever
• D. Diphtheria
• E. Encephalitis

Explanation: Diphtheria is caused by the bacterium Corynebacterium diphtheriae, not by a virus. Poliomyelitis, many cases of common cold, yellow fever and viral encephalitis are caused by viruses. Students may choose encephalitis because some cases have non-viral causes, but viral encephalitis is a recognized viral disease.

2303. The Viruses are: ____________?

• A. Cellular
• B. Prokaryotes
• C. Non-cellular
• D. Eukaryotes

Explanation: Viruses are non-cellular because they lack cytoplasm, ribosomes and independent cellular metabolism. Students may choose prokaryotes because viruses are smaller and simpler than cells, but prokaryotes are still complete cellular organisms. Therefore, option c is correct.

2304. The Nucleic acid of nearly all bacteriophage is: __________?

• A. RNA
• B. Protein
• C. DNA
• D. None of these

Explanation: Nearly all known bacteriophages have DNA as their genetic material, although a small number of phages possess RNA genomes. Students may choose protein because the capsid is made of protein, but the question asks for the nucleic acid, not the coat. Therefore, option c is the expected answer.

2305. Which of the following is not a viral disease?

• A. Cowpox
• B. Mumps
• C. Tetanus
• D. Small pox

Explanation: Tetanus is caused by the bacterium Clostridium tetani, whereas cowpox, mumps, and smallpox are viral diseases. Students may choose cowpox because its name suggests an animal-associated bacterial infection, but it is caused by a poxvirus. The bacterial nature of tetanus makes option c the non-viral disease.

2306. Which disease has been totally eradicated from the world because of effective vaccination?

• A. Measles
• B. Polio
• C. Small pox
• D. Hepatitis

Explanation: Smallpox was eradicated worldwide through an effective coordinated vaccination programme, and the World Health Organization declared eradication in 1980. Polio has been eliminated from many regions but has not been eradicated globally, so it is the likely alternative students choose. Measles and hepatitis also remain present in the world.

2307. Which disease can be controlled by vaccination?

• A. Measles
• B. Cancer
• C. Diabetes
• D. Heart attack

Explanation: Measles is caused by a virus and can be effectively prevented through vaccination, which prepares immune memory before infection occurs. Cancer may be chosen because vaccines such as HPV vaccine reduce the risk of some cancers, but cancer as a broad group is not generally controlled by routine vaccination in the way measles is.

2308. Smallest disease causing agents in plants are ?

• A. virion
• B. mycoplasma
• C. viroids
• D. prions

Explanation: Viroids are the smallest known infectious agents of plants and consist only of short, circular strands of RNA without a protein coat. Virions may be selected because they are complete virus particles, but they are larger and contain a nucleic acid genome enclosed in a capsid.

2309. Which of the following pathogen type cause disease that can be treated with antibiotics ?

• A. bacteria
• B. fungi
• C. virus
• D. none of these

Explanation: Bacteria cause many diseases that can be treated with antibiotics because antibiotics target bacterial structures or processes, such as cell-wall formation or protein synthesis. Viruses lack these bacterial targets and are not killed by ordinary antibiotics, which makes option c the common misconception.

2310. Which of the following is correct for a virus?

• A. It is a non-cellular entity
• B. Obligate parasite
• C. Ultramicroscopic in size
• D. All of these

Explanation: Viruses are non-cellular particles made of genetic material surrounded by a protein coat, and they are usually ultramicroscopic. They cannot reproduce independently and must use the machinery of a living host cell, so they are obligate intracellular parasites. Students may select only option b because parasitism is the best-known feature, but all three statements describe viruses.