All Free Biology MCQs with Answers

• A. Uncoating
• B. Reverse Transcription
• C. Provirus
• D. Assembly

Explanation: "The explanation for this question will be added soon!"

• A. Blood Plasma
• B. Plant cell
• C. Skin cell
• D. Hepatocytes

Explanation: Viruses are obligate intracellular parasites, meaning they require a host cells machinery to replicate and produce new viral particies.

• A. 1/10 times
• B. 1/100 times
• C. 1/10,000 times
• D. 1/1000 times

Explanation: The volume of a bacteriophage is about 1/1000th the volume of its host.

• A. Infections Hepatitis
• B. Serum Hepatitis
• C. Infusion Hepatitis
• D. Delta Hepatitis

Explanation: Hepatitis C virus is RNA enveloped virus that causes infusion hepatitis.

• A. Paramyxovirus
• B. Rhinovirus
• C. Arbovirus
• D. Rhabdovirus
• E. Poliovirus

Explanation: Rabies is a viral disease that affects the central nervous system and is caused by the Rhabdovirus.

• A. Protozoans
• B. Algae
• C. Bacteria
• D. Fungi
• E. Virus

Explanation: Hepatitis is an inflammation of the liver, and it can be caused by several factors, including viral infections.

• A. Within 15 days of sexual contact with an infected person
• B. When the infected retrovirus enters host cells
• C. When HIV damages a large number of helper T-lymphocytes
• D. When the viral DNA is produced by reverse transcriptase

Explanation: AIDS is a condition that arises when the immune system is severely compromised due to a significant reduction in CD4 cells, which are…

• A. Helper T-Lymphocytes
• B. B-lymphocytes
• C. Leukocytes
• D. None of these

Explanation: AIDS (acquired immunodeficiency syndrome), a syndrome, is caused by the retrovirus HIV (human immunodeficiency virus).

• A. Rabies, Mumps
• B. Cholera, Tuberculosis
• C. Typhoid, Tetanus
• D. AIDS, Syphilis

Explanation: Mumps is an infectious disease that causes fever, difficulty in opening the mouth, and painful swelling of the parotid glands, which lie…

• A. DNA is enclosed in a protein coat
• B. Prokaryotic nucleus
• C. Single chromosome
• D. Both DNA and RNA

Explanation: The most accurate statement about viruses is that they contain genetic material (either DNA or RNA) enclosed in a protein coat, and they…

• A. DNA is not present at any stage in the life cycle of retroviruses
• B. Retroviruses carry a gene for RNA-dependent DNA polymerase
• C. The genetic material in mature retroviruses is RNA
• D. Retroviruses are causative agents for certain kinds of cancer in humans

Explanation: Retroviruses are unique viruses with a complex life cycle, and their features help explain which statements are true or false.

• A. 100 × 150 nm
• B. 150 × 250 nm
• C. 300 × 20 nm
• D. 300 × 180 nm.

Explanation: The Tobacco Mosaic Virus (TMV) is a rod-shaped (tubular) filament measuring about 300 nanometers (nm) in length and 20 nanometers (nm) in…

• A. Stanley
• B. Pasteur
• C. Ivanowsky
• D. D' Herelle

Explanation: Stanley was the first scientist to crystallize the tobacco mosaic virus (TMV) in 1935.

• A. Bacteriophage
• B. Retrovirus
• C. Hepatitis
• D. Icosahedral virus

Explanation: Option B is correct. Retroviruses use RNA as their genetic material and employ reverse transcriptase to form DNA, which integrates into…

• A. Viral DNA becomes incorporated into the host chromosome.
• B. The 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: In the lysogenic cycle, the viral DNA integrates into the host cell's chromosome and becomes part of the host genome, forming a prophage…

• A. Blood transfusion
• B. Oro-faecal route
• C. Insect bites
• D. Sexual contact

Explanation: Hepatitis A is primarily transmitted through the faecal-oral route, which occurs when food or water contaminated with faeces from an…

• A. Sensory neuron
• B. Interneurons
• C. Motor neuron
• D. Autonomic neurons

Explanation: Poliomyelitis mainly targets the motor neurons responsible for voluntary muscle movement, leading to muscle weakness and paralysis.

• A. Destruction of the body's immune system
• B. Recurrent pneumonia
• C. Pulmonary tuberculosis
• D. Toxoplasmosis

Explanation: This statement is a general characteristic of HIV infection but not a specific opportunistic disease.

• A. HIV infection
• B. Reverse transcription in the HIV particles
• C. Destruction of T cells
• D. Cure after proper medication

Explanation: The false statement is D) Cure after proper medication, as there is currently no cure for HIV/AIDS.

• A. Leucocyte
• B. Monocyte
• C. Helper T-lymphocyte
• D. B-lymphocyte

Explanation: Leukocytes, or white blood cells, are immune system cells that defend the body against infections.