All Free Biology MCQs with Answers

2381. Edward Jenner prepared a vaccine against:

• A. Small pox
• B. Mumps
• C. Measles
• D. Chicken pox

Explanation: The correct option, A, is that Edward Jenner prepared a vaccine against smallpox in 1796.

2382. Whenever a virus encounters an unfamiliar organism, the virus may undergo multiple mutations and emerge as a variant that produces:

• A. Severe and novel disease
• B. Non mutated
• C. Novel disease
• D. None of these

Explanation: When a virus encounters an unfamiliar organism, it may undergo several mutations during replication. These mutations can lead to significant changes in the virus's genetic makeup, often resulting in variants capable of causing severe and novel diseases. The correct answer is "severe and novel disease" because it encompasses both the potential severity and the novelty of the disease. The other options are incorrect because:Non-mutated: This is inaccurate, as viruses generally mutate when facing new hosts.Novel disease: While true, it doesn't capture the potential severity of the disease, which is critical.None of these is incorrect; mutations often result in new disease variants.

2383. Which statement is wrong for viruses?

• A. All are parasites.
• B. All of them have helical symmetry.
• C. They don't have the ability to synthesise nucleic acids and proteins.
• D. Antibiotics have no effect on them.

Explanation: This statement is incorrect. Viruses can have different symmetries, including helical, icosahedral. or complex. structures. The structure of a virus depends on its type and can vary.

2384. Select the wrong statement

• A. The term 'contagium vivum fluidum' was coined by M. W. Beijerinck.
• B. Mosaic disease in tobacco and AIDS in human beings are caused by viruses.
• C. The viroids were discovered by D.J. Ivanovsky.
• D. W. M. Stanley showed that viruses could be crystallized.

Explanation: 1. "The term 'contagium vivum fluidum' was coined by M. W. Beijerinck." - Correct. Beijerinck coined this term for infectious agents smaller than bacteria, now known as viruses.2. "Mosaic disease in tobacco and AIDS in human beings are caused by viruses." - Correct. Mosaic disease is caused by a virus, and AIDS results from HIV, a specific virus.3. "The viroids were discovered by D.J. Ivanowsky." - Incorrect. Viroids were discovered by Theodor O. Diener, not Ivanovsky.4. "W.M. Stanley showed that viruses could be crystallized." - Correct. Stanley crystallized the tobacco mosaic virus in 1935, showing viruses could be purified and studied.

2385. The replication of the HIV virus nucleic acid depends on what?

• A. Replicase
• B. Reverse transcriptase
• C. Transcriptase
• D. Reverse replicase

Explanation: This is because HIV is a retrovirus with an RNA genome. After entering the host cell, HIV uses reverse transcriptase to convert its single-stranded RNA into double-stranded DNA. This DNA is then integrated into the host genome by another enzyme called integrase, allowing the virus to hijack the host machinery for producing viral proteins and new viral particles.

2386. A person with a viral load of HIV-1, if untreated, leads to:

• A. Cancer
• B. Hepatitis
• C. Jaundice
• D. AIDS

Explanation: Option D is incorrect, as if a person with HIV-1 is untreated, the virus can eventually destroy the immune system. This is called AIDS. AIDS is a serious condition that can lead to death.

2387. Nowadays every newborn gets regular shots of vaccine for polio. It contains _ for polio to make a child immune against this disease.

• A. Antibiotics
• B. Antibodies
• C. Antigens
• D. Antisera

Explanation: A vaccine elicits an immune response by the host so that the host is better equipped to fight against the invading organism, in any potential future instance, via the production of memory cells. It may do so by containing the antigens of the invading organism (in this case, poliovirus) so that the host's immune system produces memory cells against the specific organism, thereby conferring active immunity against the disease. Antibiotics (option A) are not present in vaccines; they are drugs used to treat bacterial illnesses. Antibodies (option B) are not present in vaccines; they are proteins, produced by plasma cells, to ward off infection. They are produced by the immune system to fight an active infection, but they are not used in vaccines since they do not confer active immunity as the host does not produce memory cells against the invading organism. Antisera (option D) is a blood serum preparation that contains antibodies against a certain antigen or disease; they are used as a treatment for certain conditions and do not confer active immunity to the individual.

2388. Each sentence below has a blank indicating that something has been omitted. Choose the word that best fits in with the meaning of the sentence as a whole.Mani suffered one final ignominy after death when his tomb was _.

• A. Consecrated
• B. Secured
• C. Vitalized
• D. Desecrated

Explanation: An "ignominy" is shame, disgrace, or humiliation, so because he suffered one final "ignominy" after death, we can infer that his tomb must have been "desecrated," which means defiled, disrespected, or dishonored. "Absolved" means forgiven or removed blame from; "vitalized" means gave strength and energy to; and "secured" means fixed so something can't be moved or assured the protection of.

2389. Spot the error. It is time we decided who side we are on, the University of Bath or the people of Swindon.

• A. decided
• B. who
• C. on
• D. the

Explanation: The error in the sentence is in option (B) "who." It should be corrected to "which" to correctly refer to the choice between sides in the sentence.

2390. CHOOSE THE CORRECT OPTIONS.

• A. A more unjust the king is, a more troubled his country will be.
• B. The more unjust the king is, the more troubled his country will be.
• C. More unjust the king is, more troubled his country will be.
• D. The more unjust king is, more troubled his country will be.

Explanation: This sentence is grammatically correct and idiomatic. It uses the correct correlative conjunctions "the more... the more" to express a proportional relationship between the king's level of injustice and the country's level of trouble.