Free Biodiversity and Variety of Life MCQs with Answers

241. In lytic cycle of bacteriophage, the phage is regarded as:

• A. Master
• B. Inducer
• C. Guest
• D. Slave

Explanation: Bacteriophage is called master in lytic cycle.In lytic cycle,virus takes the charge of the metabolic machinery of the host and order it to form copies of viral genome.So in this cycle, virus is called master while host is called slave.

242. The bacteriophage replicates only inside the:

• A. Animal cell
• B. Bacterial cell
• C. Fungal cell
• D. Both A & B

Explanation: Bacteriophages, also known as phages, are viruses that infect and replicate only in bacterial cells.

243. The part of bacteriophage that enters the host cell is:

• A. Protein sheath
• B. Genome
• C. Protein coat
• D. Tail

Explanation: Genome of bateriophage enters the host cell.Here is the explaination of each of the options:1. **Protein Sheath**: The protein sheath of a bacteriophage is a structure that surrounds and protects the genetic material of the virus. It is not the part that enters the host cell.2. **Genome**: The genome of a bacteriophage is its genetic material, typically composed of DNA or RNA. This is the part that enters the host cell. Once inside the host cell, it directs the host machinery to replicate and produce more phage particles.3. **Protein Coat**: The protein coat, also known as the capsid, is the outer shell of the bacteriophage. It encases the genetic material (genome) of the virus. While the protein coat does play a crucial role in the attachment and injection of the genome into the host cell, it is not the part that directly enters the cell.4. **Tail**: The tail of a bacteriophage is involved in attaching to the host cell and injecting the genetic material (genome) into the host. It serves as a delivery system for the genome.So, to directly answer your question, the part of the bacteriophage that enters the host cell is the **genome**.

244. The bacteriophage attaches itself by its tail to the cell wall of bacterium at:

• A. Anywhere on the cell
• B. Adhering surface
• C. Receptor site
• D. Binding site

Explanation: Bacteriophage attaches on specific receptor site on the surface of bacterial cell.The bacteriophage replicates only inside the bacterial cell. The first step in the replication of a bacteriophage is its attachment (adsorption) to host cell at receptor site on the cell wall of bacterium. During attachment, week chemical union between virion and receptor site takes place.So, it is the correct answer.

245. When a virus is in the lysogenic cycle, which of these will occur?

• A. Viral DNA becomes incorporated into the host DNA.
• B. Host cell produces many new viruses before it breaks apart.
• C. The viral DNA replicates and it is separated by the cell's spindle apparatus
• D. Antiviral defenses of the cell expel the viral DNA

Explanation: The virus uses the host to help copy its DNA or genetic information, but it is not producing any proteins.In the lysogenic cycle of a virus, the following events occur:1. Viral DNA becomes incorporated into the host DNA: In the lysogenic cycle, the viral DNA integrates into the host cell's DNA. This integration is typically a stable and long-term event. The viral DNA becomes part of the host genome, and this integrated viral DNA is called a prophage in the case of bacteriophages or a provirus in the case of animal viruses. The viral genes are essentially dormant at this stage and do not immediately command the host cell to produce new viruses.2. Host cell produces many new viruses before it breaks apart:This statement describes the lytic cycle, not the lysogenic cycle. In the lytic cycle, the host cell is hijacked by the viral genetic material to replicate and produce many new viruses before eventually bursting (lysing) and releasing the viral progeny.3. The viral DNA replicates and is separated by the cell's spindle apparatus: The separation by the cell's spindle apparatus is a process that occurs during cell division (mitosis or meiosis) and is not directly related to the viral life cycle. In the lysogenic cycle, viral DNA is integrated into the host DNA and does not undergo replication or separation by the spindle apparatus until the cell decides to enter the lytic cycle.4. Antiviral defenses of the cell expel the viral DNA: Typically, in the lysogenic cycle, the viral DNA is not expelled by the host cell's antiviral defenses. Instead, the viral DNA becomes a part of the host's genome and remains dormant until certain triggers prompt it to enter the lytic cycle.So, the correct statement for the lysogenic cycle is the first one: "Viral DNA becomes incorporated into the host DNA."

246. Enzyme that is present in a virus also:

• A. Dehydrogenase
• B. Urease
• C. Lysozyme
• D. Arginase

Explanation: Lysozyme is an ubiquitous enzyme present in all living organisms and viruses to breakdown cell walls.

247. Most commonly, lesions can be seen around mouth, lips and at other skin sites in:

• A. Influenza
• B. Polio
• C. Mumps
• D. Herpes

Explanation: Lesions around the mouth and lips are most commonly associated with herpes (specifically HSV-1). Mumps can also lead to facial swelling, but it's not considered skin lesions in the traditional sense. Influenza and polio do not typically cause such lesions.

248. Viral inflammation of parotid gland is commonly associated with:

• A. Mumps
• B. Small pox
• C. Herpes simplex
• D. Influenza

Explanation: Mumps belongs to group paramyxoviruses. It is highly contagious and this disease cause painful swelling of parotid glands.Mumps is a viral infection caused by the mumps virus. It can cause swelling of the salivary glands, which are located near the jaw and can lead to swelling of the cheeks. While mumps doesn't cause skin lesions, the swelling of the salivary glands can give the appearance of facial lesions.Other three options have diseases with different symptoms.

249. All of the following are viral diseases except:

• A. Influenza
• B. Polio
• C. Mumps
• D. Tetanus

Explanation: So, among the options, "Tetanus" is not a viral disease; it's a bacterial infection caused by Clostridium tetani. The other three options (Influenza, Polio, and Mumps) are indeed viral diseases.

250. Hepatitis A virus is:

• A. ssRNA
• B. dsRNA
• C. dsDNA
• D. ssDNA

Explanation: Viruses can be classifying on the bases of genome, HAV contains single standard RNA. HBV contains DNA and HCV contains RNA.Hepatitis A virus has a single-stranded RNA genome, which means its genetic material consists of a single strand of RNA.