Free Biodiversity and Variety of Life MCQs with Answers

441. HIV belongs to a special class of virus known as:

• A. Retrovirus
• B. Flavivirus
• C. Novavirus
• D. Tetanus

Explanation: HIV belongs to a special class of virus known as retrovirus. Retroviruses are a type of virus that uses RNA as its genetic material. They are also unique in that they use an enzyme called reverse transcriptase to convert their RNA genome into DNA. This DNA is then integrated into the host cell's genome, where it can be transcribed and translated into viral proteins. Retroviruses are responsible for a number of diseases in humans and animals, including HIV/AIDS, leukemia, and lymphoma. HIV is a retrovirus that attacks the immune system, making it difficult for the body to fight off infection.

442. The complete, mature, and infectious virus particle is known as:

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

Explanation: The correct answer is c. Virion. A virion is the complete, mature, and infectious virus particle, consisting of the viral genome (DNA or RNA) enclosed within a protective protein coat called the capsid. Unlike the genome or capsid alone, which are only parts of a virus, the virion represents the fully assembled unit capable of infecting host cells.

443. Which of the following is a rod shape virus?

• A. Bacteriophage
• B. Herpes virus
• C. Hepatitis virus
• D. Tobacco mosaic virus

Explanation: Tobacco mosaic virus (TMV) is a rod-shaped virus that infects plants, particularly tobacco and other solanaceous species. It has a helical structure, with a protein coat and a single-stranded RNA genome.

444. The genome of the Human Immunodeficiency Virus (HIV) is made up of:

• A. cDNA
• B. DNA
• C. RNA
• D. rRNA

Explanation: HIV is a retrovirus with a genome made of two single-stranded RNA molecules, about 9,700 nucleotides long. It carries genes that code for its essential proteins. After entering a host cell, its RNA is converted into DNA by reverse transcriptase and then integrated into the host genome so the virus can replicate.

445. Viruses are not classified based on:

• A. Morphology
• B. Host specificity
• C. Cell membrane
• D. Envelope

Explanation: Viruses are not classified based on the presence or absence of a cell membrane because:- Viruses do not have a cell membrane like cellular organisms do. Instead, they have a protein coat called a capsid that surrounds their genetic material.- Some viruses have an envelope, which is a lipid bilayer derived from the host cell membrane, but this is not a universal characteristic among viruses.

446. The protein coat surrounding the genome of virus is called:

• A. Capsid
• B. DNA sheath
• C. Phage
• D. Viroid

Explanation: The capsule is an additional covering that surrounds the cell wall of some bacteria, providing protection against phagocytosis (engulfment by host cells), desiccation (drying out), Antibiotics and other antimicrobial agentsThe capsule is composed of polysaccharides (complex sugars) and can be found in both Gram-positive and Gram-negative bacteria.

447. Which of the following viruses is classified as an ssDNA virus?

• A. Diarrhea virus
• B. Mild rash virus
• C. Rubella virus
• D. Smallpox virus

Explanation: Parvovirus B19, which can cause mild rashes and conditions like fifth disease in children, is a single-stranded DNA virus.

448. What are capsomeres composed of?

• A. Carbohydrates
• B. Lipids
• C. Lipoprotein
• D. Proteins

Explanation: Correct. Capsomeres are protein subunits that assemble to form the viral capsid, which provides structural support and protection for the viral genome.

449. HIV belongs to which group of viruses?

• A. DNA virus
• B. DNA enveloped virus
• C. Protein tumor virus
• D. Retrovirus

Explanation: HIV (Human Immunodeficiency Virus) is an RNA virus that uses reverse transcriptase to convert its RNA into DNA inside host cells.This ability to reverse the normal flow of genetic information (RNA → DNA) classifies it as a retrovirus.

450. In how many stages is the HIV infection process divided?

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: HIV progresses through three main stages: an early phase where the person carries the virus without clear symptoms, a middle phase marked by mild illnesses and immune weakness, and a final phase where the immune system is severely damaged and full-blown AIDS develops.