All Free Biology MCQs with Answers

2831. What is the size of parvovirus?

• A. 200nm
• B. 30nm
• C. 20nm
• D. 100nm

Explanation: Parvoviruses are the smallest known animal viruses, measuring only 18-26 nanometers in diameter. They are non-enveloped viruses with an icosahedral capsid and contain a single-stranded DNA (ssDNA) genome. Because of their tiny size and simple structure, parvoviruses rely heavily on the host cell's machinery for replication. An example is the human parvovirus B19, which causes fifth disease in children.

2832. Eukaryotic, multicellular, and consumers belong to _ kingdom.

• A. Monera
• B. Protista
• C. Fungi
• D. Animalia

Explanation: Kingdom Monera: It comprises unicellular, prokaryotic organisms, which can be heterotrophic or autotrophic, having no well-defined nucleus and no organelles.Kingdom Protista: Protists are eukaryotic, unicellular organisms They can be autotrophs or heterotrophs.Kingdom Fungi: Fungi can be single-celled or very complex multicellular organisms. All fungi are heterotrophic, which means that they get the energy they need to live from other organisms.They are eukaryotes.Kingdom Animalia: They are eukaryotic, multicellular, and heterotrophic.

2833. When were bacteriophages discovered by Twort?

• A. 1915
• B. 1920
• C. 1910
• D. 1820

Explanation: Bacteriophages were first discovered by Frederick W. Twort in 1915. While working with Staphylococcus colonies, he noticed that some of them suddenly became transparent and failed to grow. Twort suggested that this was caused by a "filterable virus" capable of destroying bacteria, although he was uncertain and did not pursue the finding further.

2834. What type of virus is the smallpox virus?

• A. DNA-enveloped virus
• B. RNA-enveloped virus
• C. DNA non-enveloped virus
• D. RNA non-enveloped virus

Explanation: Viruses are classified by genome type and presence of an envelope. RNA-enveloped viruses (e.g., influenza, HIV) have RNA with a capsid and lipid coat, while RNA-non-enveloped viruses (e.g., polio, rotavirus) carry RNA only in a capsid. DNA-enveloped viruses (e.g., herpes, hepatitis B, and poxvirus) contain a large double-stranded DNA genome with both capsid and envelope, whereas DNA-non-enveloped viruses (e.g., adenovirus and papillomavirus) package DNA only in a protein shell. Notably, the poxvirus is a DNA-enveloped virus.

2835. Binomial nomenclature was proposed for the first time by:

• A. Charles Darwin (1859)
• B. Rudolph virchow (1855)
• C. Louis Pasteur (1862)
• D. Carolus Linnaeus (1707)

Explanation: Tyrannosaurus rex is probably the most widely known binomial. The formal introduction of this system of naming species is credited to Carl Linnaeus, effectively beginning with his work Species Plantarum in 1753.

2836. Which of the following best characterizes the viruses with un-enveloped plus- (I point) strand RNA?

• A. Lacking envelope
• B. Having DNA
• C. Act indirectly
• D. Enveloped

Explanation: Lacking envelope: As indicated by their name, un-enveloped plus-strand RNA viruses lack envelopes and consist only of a nucleic acid core capsid surrounded by protein viruses. Hence, this option is correct

2837. Through which of the following does rabies spread?

• A. Cat
• B. Fox
• C. Dog
• D. Pig

Explanation: Rabies is most often spread by small, mammals such as dogs, racoons and foxes, most commonly by dogs.The rabies virus is spread by the saliva of the host animal, often after bites but it can also be contracted from handling a dead infected animal.

2838. The hepatitis that passes from mother to her child during pregnancy is:

• A. Hepatitis A
• B. Hepatitis B
• C. Hepatitis C
• D. Hepatitis D

Explanation: Hepatitis B spreads through contact with infected body fluids. This includes blood, serum, saliva, breast milk, and it can also be passed on through sexual contact.

2839. Which of the following may lead to death by the age of three years?

• A. Pompe disease
• B. Gaucher's disease
• C. Tay-Sachs disease
• D. Krabbe's disease

Explanation: Tay-Sachs disease is a genetic disorder where the enzyme Hexosaminidase A is absent. It causes progressive nerve damage, loss of motor skills, blindness, seizures, and death usually by age 3.

2840. Which of the following is not related to enveloped viruses?

• A. They survive for a short time.
• B. They are tolerant to antibodies.
• C. Their envelope is sensitive to sunlight.
• D. Envelope is derived from host..

Explanation: Enveloped viruses are less resistant to antibodies or disinfectants and can be easily destroyed. The envelope is derived from the host and is sensitive to sunlight. They survive for a short time.