Free Biodiversity and Variety of Life MCQs with Answers

471. Which of the following is an example of a sub-viral particle that infects plants?

• A. Prion
• B. Viroid
• C. Bacteriophage
• D. Infectious protein

Explanation: Viroids are small, circular RNA molecules that can infect plants. They lack a protein coat and do not encode proteins, relying on the host's cellular machinery for replication. Viroids are responsible for various plant diseases, disrupting normal growth and development

472. Bacteriophages escape from host cells by the activity of:

• A. Non-Ribosome
• B. Lysozyme
• C. Peroxisome
• D. Lysosome

Explanation: Lysozyme is an enzyme that plays a crucial role in the immune system and is involved in breaking down bacterial cell walls.

473. Phage genome incorporated with host DNA is called:

• A. Bacteriophage
• B. Viroids
• C. Prophage
• D. Prions

Explanation: A prophage is the latent form of a bacteriophage (a virus that infects bacteria) when it integrates its genetic material into the bacterial chromosome. In this state, the viral DNA is replicated along with the bacterial DNA during cell division without causing immediate harm to the host. The prophage can remain dormant for extended periods, but under certain conditions, it may reactivate and enter the lytic cycle, leading to the production of new viral particles and the lysis of the bacterial cell. Prophages can play a role in horizontal gene transfer, contributing to genetic diversity among bacteria and sometimes providing advantageous traits, such as antibiotic resistance. Understanding prophages is important in microbiology and virology, particularly in studying bacterial evolution and the dynamics of bacterial infections.

474. Example of viruses having a polyhedral capsid that is with 252 capsomeres is:

• A. Adenovirus
• B. Tobacco Mosaic Virus
• C. Influenza virus
• D. Bacteriophage

Explanation: The capsid of adenovirus typically contains 52 capsomeres. This includes 240 hexon capsomeres and 12 penton capsomeres at the vertices.

475. The complete, mature & infectious particle of virus is known as:

• A. Genome
• B. Capsomere
• C. Virion
• D. Envelope

Explanation: A virion is the fully assembled, infectious form of a virus when it's outside a host cell. It includes the genetic material along with its protective protein coat, and sometimes an envelope, allowing it to survive in the environment and infect new cells.

476. The causative organism of measles is:

• A. Poxivirus
• B. Paporivirus
• C. Picornovirus
• D. Paramyxovirus

Explanation: Measles is caused by the measles virus, which is an RNA virus belonging to the Morbillivirus genus within the Paramyxoviridae family. The virus primarily infects the respiratory tract and can spread throughout the body, leading to the characteristic symptoms of measles, including fever, cough, runny nose, conjunctivitis, and the distinctive rash.

477. In the life cycle of a bacteriophage, the lysozymes are required in which of the following steps of the infection process?

• A. Genome injection
• B. Penetration
• C. Replication
• D. Adsorption

Explanation: Penetration in the context of bacteriophages refers to the process by which the phage injects its genetic material into a bacterial host cell after successfully adsorbing to the bacterial surface. This step is critical for the viral life cycle as it enables the phage to hijack the host's cellular machinery to replicate and produce new phage particles. L ysozyme hydrolyzes the peptidoglycan layer in bacterial cell walls, leading to cell lysis and death

478. During which stage of bacteriophage replication, lysozyme is involved?

• A. Adsorption
• B. Attachment
• C. Multiplication
• D. Penetration

Explanation: The bacteriophage releases lysozyme, an enzyme that breaks down the bacterial cell wall, allowing the viral genetic material to enter and later helping in the release of new phages by breaking open the cell.

479. The side of sheath attached to head region in bacteriophage is termed as

• A. Capsid
• B. Collar
• C. Core
• D. End plate

Explanation: The collar of a bacteriophage is a structural component that connects the capsid to the tail. It serves as a junction between the head (capsid) containing the viral genetic material and the tail, which is used for attachment to host bacteria and injecting the viral genome into them. The collar is typically made up of protein subunits and may play a role in the phage's ability to recognize and attach to specific bacterial surfaces.

480. Who purified filterable agents for the first time?

• A. Charles Chamberland
• B. Ivanowski
• C. Louis Pasteur
• D. Stanley

Explanation: Wendell Meredith Stanley was the first to purify a virus, specifically the Tobacco Mosaic Virus (TMV) in 1935. He showed that TMV could be crystallized like a chemical and still remain infectious, which was a major breakthrough. This discovery helped prove that viruses were distinct from other microorganisms and opened the door to modern virology.