1. Which protein is primarily involved in muscle contraction as per the sliding filament theory?
    a) Collagen
    b) Actin
    c) Myosin
    d) ElastinAnswer: b) Actin
  2. According to the sliding filament theory, muscle contraction occurs when:
    a) The Z-discs move further apart
    b) The thick and thin filaments slide past each other
    c) The sarcoplasmic reticulum increases in volume
    d) Calcium ions are removed from the cytoplasmAnswer: b) The thick and thin filaments slide past each other
  3. What is the role of calcium ions in muscle contraction?
    a) To cause the actin filaments to shorten
    b) To bind to troponin, exposing binding sites on actin
    c) To form cross-bridges between actin and myosin
    d) To energize the myosin headsAnswer: b) To bind to troponin, exposing binding sites on actin
  4. Which of the following proteins blocks the binding sites on actin in a relaxed muscle?
    a) Tropomyosin
    b) Myosin
    c) Titin
    d) TroponinAnswer: a) Tropomyosin
  5. The power stroke in muscle contraction is caused by:
    a) The release of ATP
    b) The movement of myosin heads
    c) The breakdown of calcium ions
    d) The release of acetylcholineAnswer: b) The movement of myosin heads
  6. What happens during the muscle contraction in the sliding filament theory?
    a) The Z-discs move closer together
    b) The length of the actin filaments increases
    c) The myosin filaments move along the actin filaments
    d) The sarcomere length remains constantAnswer: a) The Z-discs move closer together
  7. Which molecule provides energy for the myosin heads during muscle contraction?
    a) Glucose
    b) ATP
    c) Creatine phosphate
    d) NADHAnswer: b) ATP
  8. The process of myosin head detachment from actin after the power stroke requires:
    a) ATP
    b) Calcium ions
    c) Sodium ions
    d) OxygenAnswer: a) ATP
  9. In the sliding filament theory, which structure gets shortened during contraction?
    a) Myosin
    b) Actin
    c) Sarcomere
    d) Z-discAnswer: c) Sarcomere
  10. Which ion is released from the sarcoplasmic reticulum to initiate muscle contraction?
    a) Potassium
    b) Calcium
    c) Sodium
    d) ChlorideAnswer: b) Calcium
  11. What is the function of troponin in muscle contraction?
    a) To release ATP for myosin
    b) To regulate calcium ion concentration
    c) To bind to calcium ions, changing the shape of tropomyosin
    d) To form cross-bridges with actinAnswer: c) To bind to calcium ions, changing the shape of tropomyosin
  12. During muscle contraction, which of the following is true?
    a) The A-band becomes narrower
    b) The I-band becomes wider
    c) The H-zone disappears
    d) The sarcomere length increasesAnswer: c) The H-zone disappears
  13. What prevents the muscle from contracting in the absence of a nerve impulse?
    a) Tropomyosin blocking the actin-binding sites
    b) Calcium ions bound to troponin
    c) Myosin heads are unphosphorylated
    d) The absence of acetylcholineAnswer: a) Tropomyosin blocking the actin-binding sites
  14. What is the role of the transverse tubules (T-tubules) in muscle contraction?
    a) To transport ATP to the muscle
    b) To carry the nerve impulse deep into the muscle fibers
    c) To release calcium ions into the cytoplasm
    d) To contract the actin filamentsAnswer: b) To carry the nerve impulse deep into the muscle fibers
  15. Which of the following structures is responsible for the storage of calcium ions in muscle cells?
    a) Mitochondria
    b) Sarcoplasmic reticulum
    c) Golgi apparatus
    d) Endoplasmic reticulumAnswer: b) Sarcoplasmic reticulum
  16. Which of the following events must occur for a muscle to relax after contraction?
    a) ATP must bind to troponin
    b) Calcium ions must be pumped back into the sarcoplasmic reticulum
    c) Myosin heads must bind to actin
    d) Tropomyosin must block the actin-binding sitesAnswer: b) Calcium ions must be pumped back into the sarcoplasmic reticulum
  17. The “sliding” in the sliding filament theory refers to:
    a) The actin filaments sliding past the myosin filaments
    b) The myosin filaments sliding past the actin filaments
    c) The sliding of Z-discs
    d) The sliding of muscle fibers along each otherAnswer: a) The actin filaments sliding past the myosin filaments
  18. The myosin heads attach to actin filaments to form:
    a) Cross-bridges
    b) Synapses
    c) Myofibrils
    d) SarcomeresAnswer: a) Cross-bridges
  19. Which of the following is responsible for the muscle’s ability to generate force during contraction?
    a) Release of calcium ions
    b) The breakdown of ATP
    c) The sliding of myosin along actin
    d) The shortening of the sarcomereAnswer: c) The sliding of myosin along actin
  20. What is the role of ATP in muscle contraction?
    a) It helps in the detachment of the myosin head from actin
    b) It helps in the binding of actin to myosin
    c) It releases calcium ions from the sarcoplasmic reticulum
    d) It energizes the muscle to relaxAnswer: a) It helps in the detachment of the myosin head from actin
  21. The thick filaments of a muscle fiber are made up of which protein?
    a) Actin
    b) Myosin
    c) Tropomyosin
    d) TitinAnswer: b) Myosin
  22. The I-band in a sarcomere represents:
    a) The region where only thick filaments are present
    b) The region where only thin filaments are present
    c) The overlap region between actin and myosin
    d) The zone where the sarcomere attaches to the Z-discAnswer: b) The region where only thin filaments are present
  23. Which of the following is the correct order of events in muscle contraction?
    a) ATP binds to myosin → Calcium ions are released → Tropomyosin shifts → Myosin heads form cross-bridges
    b) Myosin heads form cross-bridges → ATP binds to myosin → Calcium ions are released → Tropomyosin shifts
    c) Calcium ions are released → Tropomyosin shifts → ATP binds to myosin → Myosin heads form cross-bridges
    d) Tropomyosin shifts → Myosin heads form cross-bridges → ATP binds to myosin → Calcium ions are releasedAnswer: c) Calcium ions are released → Tropomyosin shifts → ATP binds to myosin → Myosin heads form cross-bridges
  24. The role of myosin in muscle contraction is to:
    a) Bind to calcium ions
    b) Form cross-bridges with actin filaments
    c) Regulate the release of ATP
    d) Bind to troponinAnswer: b) Form cross-bridges with actin filaments
  25. What is the H-zone in a sarcomere?
    a) The region where actin and myosin overlap
    b) The space between two Z-discs
    c) The region where only myosin filaments are present
    d) The area where cross-bridges formAnswer: c) The region where only myosin filaments are present
  26. What happens during muscle relaxation?
    a) The myosin heads continue to bind to actin
    b) Calcium ions are pumped back into the sarcoplasmic reticulum
    c) The sarcomere shortens further
    d) The Z-discs move further apartAnswer: b) Calcium ions are pumped back into the sarcoplasmic reticulum
  27. Which of the following ions is crucial for the contraction of skeletal muscles?
    a) Potassium
    b) Chloride
    c) Sodium
    d) CalciumAnswer: d) Calcium
  28. Which structure in a muscle fiber contains both actin and myosin filaments?
    a) Sarcoplasmic reticulum
    b) Myofibrils
    c) Mitochondria
    d) Z-discAnswer: b) Myofibrils
  29. Which part of the muscle fiber contains the actin filaments?
    a) A-band
    b) I-band
    c) M-line
    d) H-zoneAnswer: b) I-band
  30. What causes the shortening of the sarcomere during muscle contraction?
    a) The actin filaments slide past myosin
    b) The myosin heads detach from actin
    c) ATP binds to troponin
    d) The sarcoplasmic reticulum contractsAnswer: a) The actin filaments slide past myosin

RELATED ARTICLESMORE FROM AUTHOR

LEAVE A REPLY

Please enter your comment!
Please enter your name here