All Free Biology MCQs with Answers

• A. H band
• B. A band
• C. I band
• D. M band

Explanation: Option C is correct.The light band of a sarcomere is called the I band.

• A. Strength
• B. Nourishment
• C. Striped appearance
• D. Protection

Explanation: Option C is correct.The light and dark bands of muscle cells give the muscle cell as a whole its striated appearance.

• A. Tendons and ligaments
• B. Thick filaments
• C. Thin filaments
• D. Both B and C

Explanation: Option D is correct. Myofibrils are the contractile units of muscle fibers. They are made up of repeating units called sarcomeres.

• A. Myofibril
• B. Muscle fibre
• C. Muscle bundle
• D. Myoglobin

Explanation: Option A is correct. Myofibrils are the contractile units of muscle fibers. They are made up of repeating units called sarcomeres.

• A. 16 µm
• B. 7-8 nm
• C. 1-2 µm
• D. 16 nm

Explanation: Option D is correct.Yes, the diameter of a thick filament in a sarcomere is about 16 nanometers.

• A. Two globular heads
• B. Two linear heads
• C. A globular head
• D. A linear head

Explanation: Option A is correct.Each myosin molecule has a long, rod-shaped tail that is made up of two myosin-heavy chains.

• A. Cross Fibres
• B. Cross bridges
• C. Cross connection
• D. Both B and C

Explanation: Option D is correct. The globular heads of myosin filaments link the thick and the thin myofilaments together during muscle contraction.

• A. 1-2 µm
• B. 10-60 µm
• C. 7-8 nm
• D. 16 nm

Explanation: Option C is correct.The diameter of a thin filament in a sarcomere is about 7-8 nanometers.

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

Explanation: Option A is correct.Thin filaments are composed chiefly of actin. Actin is a protein that makes up the thin filaments of muscle cells.

• A. Myosin filament
• B. Binding sites of myosin filament
• C. Binding sites on actin filament
• D. Actin filament

Explanation: Myosin heads bind to the binding sites on actin filaments to make cross bridges.

• A. Extend
• B. Move slightly
• C. Contract
• D. Remain in the same position

Explanation: When the muscle is required to contract, calcium ions bind with troponin molecule and cause them to move slightly.This has the effect of…

• A. ATP is synthesized and the bridge goes to its cycle
• B. ATP is hydrolyzed and the bridge goes to its cycle
• C. ATP is synthesized and the bridge becomes fixed
• D. ATP is hydrolyzed and the bridge becomes fixed

Explanation: Muscle contraction is a highly active process and ATPs are consumed at each step i.e.

• A. One after other
• B. Simultaneously
• C. Separately
• D. Now or then simultaneously

Explanation: The contraction of each muscle fiber is based on the "All or none" principle i.e. all of its fibrils participate in contraction.

• A. Z-line
• B. A and I junction
• C. Z-line or A and I Junctions
• D. M-line or A and I Junctions

Explanation: It is to ensure the transmission of impulse.

• A. Accumulation of ATPs
• B. Aerobic breakdown of glucose
• C. Overactive metabolism
• D. Lactic acid accumulation

Explanation: It accumulates as a result of anaerobic respiration and accumulation of acid lowers the pH

• A. Cramp
• B. Muscle fatigue
• C. Tetany
• D. Tetanus

Explanation: Tetany has symptoms that involve involuntary muscle contractions and overly stimulated peripheral nerves.

• A. Two
• B. Four
• C. Three
• D. Six

Explanation: Vertebrates possess 3 kinds of muscles; Skeletal, smooth, and cardiac.

• A. Smooth muscles
• B. Skeletal muscles
• C. Voluntary muscles
• D. Involuntary muscles

Explanation: Skeletal muscles have regular striations or strips converting the surface into alternating light and dark bands.

• A. Smooth muscles
• B. Cardiac muscles
• C. Skeletal muscles
• D. Involuntary muscles

Explanation: Skeletal muscle cells are multinucleate.

• A. Spontaneous stimuli
• B. Nervous system & hormonal stimuli
• C. Stretch stimuli
• D. Spontaneous, stretch, nervous & hormones

Explanation: Causes of contraction of smooth muscles are diverse.