Solution: A
Attachment is the first stage in the infection process in which the phage interacts with specific bacterial surface receptors. Most phages have a narrow host range and may infect one species of bacteria or one strain within a species.

The second stage of infection is entry or penetration. This occurs through the contraction of the tail sheath, which acts like a hypodermic needle to inject the viral genome through the cell wall and membrane. The phage head, capsid, and remaining components remain outside the bacteria.

Solution: B
The HIV genome consists of two identical single-stranded RNA molecules that are enclosed within the core of the virus particle.

Solution: D
The volume of the phage is about 1/1000 of the host.The bacteriophage replicates only inside the bacterial cell.

Solution: D
The DNA replicates before the cell division. The cells under the influence of HIV are unable to divide or replicate their DNA.

Choice A & Choice C: In the life cycle of HIV, Transcription of proviral DNA takes place in order to synthesize viral proteins by Translation.
Choice B: Reverse transcription is a special feature of all retroviruses.

Solution: A
A prophage refers to a viral genome that has been integrated into the host cell’s genome. It remains dormant within the host cell until it is activated.

Solution: C
Mouth, lips, and skin are affected due to the infection of the Herpes virus. Oral herpes is an infection of the lips, mouth, or gums due to the herpes simplex virus. It causes small, painful blisters commonly called cold sores or fever blisters. Oral herpes is also called herpes labialis.

Solution: D
Common cold in humans is caused by the Adenovirus. Adenoviruses are common viruses that cause a range of illnesses. They can cause cold-like symptoms, fever, sore throat, bronchitis, pneumonia, diarrhea, and pink eye (conjunctivitis). You can get an adenovirus infection at any age.

Solution: C
The protein capsid provides the second major criterion for the classification of viruses. The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid.

Solution: B
Not all oncoviruses are DNA viruses. Some RNA viruses have also been associated such as the hepatitis C virus as well as certain retroviruses
Hep B producing virus is not retrovirus
All RNA viruses are not retroviruses but all retroviruses are RNA virus

Solution: B
During penetration, the bacteriophage tail releases lysozyme to dissolve a portion of the bacterial cell wall.

Solution: C
Rhizobium is a genus of bacteria associated with the formation of root nodules on plants. These bacteria live in symbiosis with legumes. They take in nitrogen from the atmosphere and pass it on to the plant, allowing it to grow in soil low in nitrogen.

Solution: B
A bacteriophage is a type of virus that infects bacteria. In fact, the word "bacteriophage" literally means "bacteria eater," because bacteriophages destroy their host cells. All bacteriophages are composed of a nucleic acid molecule that is surrounded by a protein structure.

Solution: C
When the viral nucleic acid takes control of the bacterial biosynthetic machinery and after reproduction, it bursts into the bacterial cell. This is known as virulent or lytic phage.

Solution: D
Viruses lack metabolic machinery of their own to generate energy and synthesize proteins, carbohydrates, and alcohols. Unlike living cells, viruses are obligate intracellular parasites that rely on the host cell's metabolic machinery to carry out their replication and protein synthesis. They lack the necessary enzymes and organelles for energy production and the synthesis of complex molecules. Instead, viruses hijack the host cell's resources and utilize them to replicate their genetic material and produce viral proteins.

Solution: C
AIDS will lead to opportunistic infections. When someone living with HIV has a weakened immune system, they are at risk of 'opportunistic infections' which is when infections take the opportunity of the immune system being weak. Common opportunistic infections associated with HIV include cryptococcal meningitis. toxoplasmosis.

Solution: C
Small pox is caused by DNA enveloped virus. Smallpox is a double-stranded, DNA virus that replicates in the cytoplasm of the host cell and forms B-type inclusion bodies. This is in contrast to herpes viruses, which replicate in the nucleus.

Solution: D

DNA viruses:

• Smallpox virus
• Herpes simplex virus
• Hepatitis B virus
  (All other are RNA viruses)

Non-enveloped Viruses:

• Polio virus
• Hepatitis A virus
  (All other are enveloped viruses)

Solution: B
During the life cycle of HIV virus attaches the helper T lymphocytes at the CD4 receptor site and then passes their RNA into the host cell and forms DNA by reverse transcription and then this DNA incorporate into the host DNA and is called as a provirus. Then this DNA forms RNA by transcription and proteins are formed in the cytoplasm by translation and after assembly, these are released.

Solution: B
Viruses range in size from 250 nm to 20 nm. Poxvirus is the largest known virus i-e 250nm in size and poliovirus is the smallest virus i-e. 20nm in size.

Solution: D
Both DNA and RNA viruses have been shown to be capable of causing cancer in humans.

Solution: C
Prions are infectious proteins. They cause Mad cow infection and mysterious brain infection in men.

Solution: A
Hepatitis A is called infectious hepatitis. Hepatitis A is an inflammation of the liver that can cause mild to severe illness. The hepatitis A virus (HAV) is transmitted through ingestion of contaminated food and water or through direct contact with an infectious person.

Solution: B
Milk & milk products are usually preserved through pasteurization. Pasteurization or pasteurisation is a process in which packaged and non-packaged foods (such as milk and fruit juice) are treated with mild heat, usually to less than 100 °C (212°F), to eliminate pathogens and extend shelf life.

Solution: C
HIV enters the host cell and forms DNA from reverse transcription and this DNA enters into the nucleus and viral DNA integrates into the host chromosome and is called as a provirus and then transcription occurs and when it passes out of the nucleus translation occurs.

Solution: B
The virions are composed of a central core of nucleic acid, either DNA or RNA, which is also known as the genome and is surrounded by a protein coat, the capsid. Capsid gives definite shape to virion. Capsid is made up of protein subunits known as capsomeres. The number of capsomeres is characteristics of a particular virus. For example 162 capsomeres are present in the capsid of herpes virus and 252 in the capsid of adeno virus which causes some common colds.

Solution: B
The single-stranded RNA tumor viruses, which also include retroviruses (oncoviruses), are spherical in form, about 100nm in diameter and enveloped by host plasma membrane. Retroviruses also produce cancer-causing tumors.

Solution: D
The polioviruses are the smallest known viruses and contain RNA in the spherical capsid.

Solution: D
Hepatitis A virus (HAV) is a small, non-enveloped RNA virus that is classified as a hepatovirus. It is the most common cause of acute viral hepatitis in the world. HAV is transmitted through the fecal-oral route, and it can also be transmitted through contaminated food or water.

Hepatitis E virus (HEV) is a small, non-enveloped RNA virus that is classified as a calicivirus. It is the cause of enterically transmitted non-A, non-B hepatitis (ET-NANB). HEV is transmitted through the fecal-oral route, and it can also be transmitted through contaminated food or water.

Solution: C
A bacteriophage, or phage for short, is a virus that infects bacteria. Like other types of viruses, bacteriophages vary a lot in their shape and genetic material.

Solution: C
Poliovirus, the prototypical picornavirus and causative agent of poliomyelitis, is a nonenveloped virus with a single-stranded RNA genome of positive polarity. The virion consists of an icosahedral protein shell, composed of four capsid proteins (VP1, VP2, VP3, and VP4), which encapsidates the RNA genome .Polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus. The virus spreads from person to person and can infect a person's spinal cord, causing paralysis (can't move parts of the body).

Solution: A
Poliovirus, the causative agent of paralytic poliomyelitis, is a small non-enveloped virus, with a single strand RNA genome encased in an icosahedral protein capsid.

All influenza viruses consist of single-stranded RNA as opposed to dual-stranded DNA. Influenza is a viral infection that attacks your respiratory system
Poxviruses are brick or oval-shaped viruses with large double-stranded DNA genomes
Herpes virus is a DNA virus.

Solution: A
The retrovirus known as human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS) in humans. Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to fight infection and disease.

Solution: C
Bacteriophage (the virus which infects bacteria) rapidly multiply in host bacterial cell and bacterial cell bursts after 25 minutes releasing 200 new bacteriophages.

Solution: D
D'Hérelle coined the term bacteriophage, meaning “bacteria eater,” to describe the virus's bacteriocidal ability.

Solution: B
Smallpox virus is DNA enveloped virus. In smallpox fluid-filled vesicles are formed which becomes pustules and later form pitted scars, the pocks

Solution: A
Influenza is caused by enveloped RNA virus it spreads through contact through droplet(sneezing) so it occurs in epidemic form (key word is enveloped RNA)
Herpes simplex virus 1 (HSV-1) is a double-stranded DNA virus that proliferates in the nuclei of host cells during lytic infection
Poxviruses are oval-shaped viruses with large double-stranded DNA genomes
Polio is caused by non-enveloped RNA virus

Solution: C
Prions are made up of proteins. They lack Heredity material

Solution: B
Symptoms of AIDS: General loss of immune function, Swollen lymph nodes, Sudden weight loss, Vascular cancer, Severe pneumonia.

Solution: B
HIV uncoating is defined as the loss of viral capsid that occurs within the cytoplasm of infected cells before entry of the viral genome into the nucleus.

Solution: A
HIV is an enveloped retrovirus.