All Free Biology MCQs with Answers

• A. It is a sex-linked trait
• B. Occurs due to hormonal differences between sexes
• C. Heterozygous male is normal
• D. Homozygous female is normal

Explanation: Pattern baldness, also known as androgenic alopecia, is influenced by hormonal differences, specifically the effects of androgens (male…

• A. Appendicular skeleton
• B. Hydrostatic skeleton
• C. Exoskeleton
• D. Axial skeleton

Explanation: The axial skeleton forms a vertical axis that includes the head, neck, back, and chest.

• A. Articular capsule
• B. Articular cartilage
• C. Synovial fluid
• D. Fibrocartilage

Explanation: Fibrocartilage is the tough, very strong tissue found predominantly in the intervertebral disks and at the insertions of ligaments and…

• A. Ellipsoidal
• B. Gomphosis
• C. Syndesmosis
• D. None of these options are correct

Explanation: Classification of joints is given below:

• A. Actin slides past myosin
• B. ATP supplies energy
• C. Calcium ions are involved
• D. All of these

Explanation: When muscles need to contract, calcium ions bind with the troponin molecule and cause them to move slightly. ATP is hydrolysed.

• A. Interacting
• B. Separation
• C. Both A an B
• D. None of these

Explanation: Tropomyosin blocks myosin binding sites on actin molecules, preventing cross-bridge formation, which prevents contraction in a muscle…

• A. Actin
• B. Myosin
• C. Troponin
• D. Sarcomere

Explanation: Calcium binds to troponin C, causing the conformational shift in tropomyosin that reveals myosin-binding sites on actin.

• A. Flexor muscles
• B. Extensor muscles
• C. Adductor muscles
• D. Abductor muscles

Explanation: The adductors, as a group, are responsible for bringing the legs inwards towards each other (adduction) when the leg is extended and…

• A. Tendon
• B. Ligament
• C. Reticular tissue
• D. Cartilage

Explanation: Option (a) is correct. Tendons are fibrous connective tissues that attach muscles to bones.

• A. 2
• B. 4
• C. 6
• D. 8

Explanation: In a muscle sarcomere, each myosin filament (thick filament) is surrounded by 6 actin filaments (thin filaments) at each end.

• A. 20
• B. 27
• C. 15
• D. All

Explanation: X-ray analysis has shown that on the average there are 27 amino acid units for each turn of the helix.

• A. Adenine
• B. Guanine
• C. Thymine
• D. Cytosine

Explanation: DNA and RNA differ in three ways. 1. The sugar in RNA is ribose while the sugar in DNA is 2-deoxyribose. 2.

• A. AIDS
• B. Malaria
• C. Influenza
• D. Chickenpox

Explanation: Malaria is not a viral disease and is caused by the protozoan Plasmodium.

• A. Cellular
• B. Prokaryotes
• C. Non-cellular
• D. Eukaryotes
• E. Visible with naked eye

Explanation: Viruses are classified as non-cellular because they lack the cellular structures that define living cells, such as a cell membrane…

• A. The walls of diatoms are easily destructible.
• B. 'Diatomaceous earth' is formed by the cell walls of diatoms.
• C. Diatoms are chief producers in the"Diatoms are chief producers in the oceans."
• D. Diatoms are microscopic and float passively in water.

Explanation: The wrong statement is: "Diatoms are chief producers in the oceans."Explanation of the options:1.

• A. The term 'contagium vivum fluidum' was coined by M. W. Beijerinck.
• B. Mosaic disease in tobacco and AIDS in human being are caused by viruses.
• C. The viroids were discovered by D.J.Ivanowsky.
• D. W.M.Stanley showed that viruses could be crystallised.

Explanation: The wrong statement is: "Mosaic disease in tobacco and AIDS in human beings are caused by viruses."Explanation of each statement:1.

• A. Mycoplasma
• B. Nostoc
• C. Aspergillus
• D. Funaria

Explanation: Mycoplasma (KingdomMonera) are the simplest and smallest free living prokaryotes which are devoid of a cell wall.

• A. All are parasites.
• B. All of them have helical symmetry.
• C. They don't have ability to synthesize nucleic acids and proteins.
• D. Antibiotics have no effect on them.

Explanation: "All are parasites": This statement is correct. Viruses are obligate intracellular parasites, meaning they depend on a host cell to…

• A. Prokaryotic organisms
• B. Fungi
• C. All unicellular organisms
• D. Eukaryotic organisms

Explanation: The kingdom Protoctista (also known as Protista) includes a diverse group of eukaryotic microorganisms.

• A. Type of nucleic acids
• B. Protein subunits
• C. Type of hosts
• D. Viral envelope

Explanation: The shape of the virus is determined by the shape of its capsid which is determined by its protein subunits.