All Free Biology MCQs with Answers

2851. How many pieces of ribonucleic acid (RNA) make up the genome of influenza virus?

• A. 4
• B. 6
• C. 8
• D. 10

Explanation: The influenza virus genome is composed of eight pieces of ribonucleic acid (RNA). This virus is classified as a segmented RNA virus, which means its genetic material is divided into multiple RNA segments. Each of the eight segments encodes one or more proteins that are crucial for the virus's ability to replicate and cause infection. The segmentation of the genome allows the virus to undergo reassortment, which is a process that contributes to its genetic diversity and ability to evade the immune system, leading to new strains and potential pandemics. The other options (A, B, and D) are incorrect as they misrepresent the number of RNA segments in the influenza virus genome.

2852. The head of some phages are icosahedral, which means that the head possesses:

• A. 6 Sides
• B. 10 Sides
• C. 15 Sides
• D. 20 Sides

Explanation: The head of some phages are icosahedral, which means that the head possesses 20 sides. An icosahedron is a polyhedron defined by having 20 equilateral triangular faces. It is one of the five Platonic solids, recognized for its symmetry and structural efficiency. The icosahedral shape allows for optimal packing of viral proteins and DNA, contributing to the stability and resilience of the virus against environmental stressors. Examples of phages with icosahedral heads include T4 phage, T7 phage, Lambda phage, and MS2 phage. The other options are incorrect because they do not represent the true structural nature of an icosahedron, which is specifically characterized by its 20 triangular faces.

2853. 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.

2854. 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.

2855. 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.

2856. 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.

2857. 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.

2858. 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.

2859. 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.

2860. 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.