All Free Biology MCQs with Answers

• A. Myofibril
• B. Z-line
• C. Myosin
• D. Actin

Explanation: Myosin is the primary component of the thick filament.

• A. H zone
• B. M line
• C. Z line
• D. I band

Explanation: The A band does not shorten, it remains the same length, but A bands of different sarcomeres move closer together during contraction…

• A. ATP is hydrolyzed
• B. Calcium binds to myosin heads
• C. Both A and B
• D. None of these

Explanation: Calcium binds to troponin to remove tropomyosin from the binding site. It doesn't attach directly with "myosin".

• A. Binding sites of actin get attached to the myosin head
• B. Troponin uncovers the actin binding sites
• C. Ca2+ goes back inside sarcoplasmic reticulum
• D. Tropomyosin gets removed from the binding sites of actin filaments

Explanation: Soon after the binding of Calcium ions, "tropomyosin gets removed from the binding sites of actin filaments".

• 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. Positive phototropism and negative geotropism
• B. Negative tactic movement and positive tropic movement
• C. Positive geotropism of stem and roots
• D. Negative phototropism and positive geotropism

Explanation: The roots of a plant show positive geotropism and negative phototropism because they grow towards the Earth (in response to gravity) and…

• A. Muscle relaxation
• B. Muscle contraction
• C. Muscle twitch
• D. None of these

Explanation: The process of muscle contraction takes place when the myosin (thick) filament attaches to the actin (thin) filament and slides past each…

• 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. White blood cells
• B. Bone cell
• C. Brain cell
• D. None of these

Explanation: Option A: White blood cells: Cells involved in the immune system's defense against infections and foreign substances.

• A. Hyperglycemia
• B. Hypercalcaemia
• C. Hypoglycemia
• D. Hypocalcaemia

Explanation: Option A: Hyperglycemia refers to high levels of glucose (sugar) in the blood.

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

Explanation: Option A: Tropomyosin is another protein associated with muscle contraction, but it primarily functions to regulate the interaction…

• A. Striped muscles
• B. Striated muscles
• C. Involuntary muscles
• D. Both A and B are correct

Explanation: Skeletal striated muscles, also known as striated or voluntary muscles, are a type of muscle tissue that is responsible for the movement…

• A. Radio-ulnar joints
• B. Tibiofibular joints
• C. Both A and B
• D. Sutures

Explanation: Syndesmoses are fibrous joints where two bones are connected by a ligament.

• A. Actin
• B. Myosin
• C. Myofibril
• D. Fibroin

Explanation: The answer is Myosin. Myosin is a protein that is essential for muscle contraction.

• A. Troponin binds to myosin and tropomyosin binds to actin
• B. Tropomyosin binds to actin and prevents the myosin head from binding to actin
• C. Both options A and B are correct
• D. None of these options are correct

Explanation: Option A: Troponin does not bind to myosin thus this option is incorrect.Option B: In a relaxed muscle fibre, the binding sites for myosin…

• A. H line
• B. Z line
• C. M line
• D. I line

Explanation: M line is a line at center of sarcomere to which myosin bind.OPTION A: H-band is the zone of thick filament having no actin.

• A. Osteocytes
• B. Osteoclasts
• C. Chondrocytes
• D. Osteoblasts

Explanation: Cartillages cells are calles chondrocytes.OPTION A: Osteocytes is cell that lies within the substance of fully formed bone.OPTION B…

• A. Tibia
• B. Fibula
• C. Tarsals
• D. Femur

Explanation: The hip joint is the junction where the hip joins the leg to the trunk of the body.

• A. T-tubule
• B. Sarcolemma
• C. Sarcomere
• D. Sarcoplasmic reticulum

Explanation: Calcium diffusing in the cytoplasm between myosin and actin filaments of the muscle fibrils causes the filaments to slide into each other…

• A. Voluntary
• B. Involuntary
• C. Both Options A and B are correct
• D. None of these options is correct

Explanation: Skeletal muscles comprise 30 to 40% of your total body mass. They're the muscles that connect to your bones and allow you to perform…