AP Biology Questions on Skeletal Muscle Groups and Movement

📚 Quick Study Guide

• 🔬 Skeletal Muscle Function: Responsible for voluntary movements; attached to bones via tendons.
• 💪 Muscle Fiber Types:
  • ⚡ Type I (Slow Oxidative): Endurance, fatigue-resistant.
  • 🔥 Type IIa (Fast Oxidative): Moderate power and fatigue resistance.
  • 💥 Type IIb (Fast Glycolytic): Powerful, but fatigue quickly.
• 🧠 Sliding Filament Theory: Muscle contraction occurs as actin and myosin filaments slide past each other, shortening the sarcomere.
• 🧪 Sarcomere Structure: Functional unit of muscle; includes:
  • Z lines: Boundaries of the sarcomere.
  • M line: Middle of the sarcomere.
  • A band: Contains myosin.
  • I band: Contains actin only.
• 🎯 Neuromuscular Junction: Where motor neuron meets muscle fiber; acetylcholine (ACh) is the neurotransmitter.
• 📈 ATP's Role: ATP is crucial for muscle contraction and relaxation; powers the myosin head movement and calcium pumps.
• 🦴 Types of Movement:
  • Flexion: Decreases joint angle.
  • Extension: Increases joint angle.
  • Abduction: Movement away from the midline.
  • Adduction: Movement towards the midline.
  • Rotation: Movement around an axis.

🧪 Practice Quiz

1. Which of the following best describes the role of ATP in muscle contraction?
   1. A. It blocks the binding of actin and myosin.
   2. B. It provides the energy for the myosin head to detach from actin.
   3. C. It inhibits the release of calcium ions.
   4. D. It directly causes the filaments to slide past each other.
2. What happens during muscle contraction according to the sliding filament theory?
   1. A. Actin filaments shorten.
   2. B. Myosin filaments shorten.
   3. C. Actin and myosin filaments slide past each other.
   4. D. The sarcomere lengthens.
3. Which muscle fiber type is best suited for endurance activities like long-distance running?
   1. A. Type IIb (Fast Glycolytic)
   2. B. Type IIa (Fast Oxidative)
   3. C. Type I (Slow Oxidative)
   4. D. Type III (Intermediate)
4. What neurotransmitter is released at the neuromuscular junction to initiate muscle contraction?
   1. A. Dopamine
   2. B. Serotonin
   3. C. Acetylcholine (ACh)
   4. D. Norepinephrine
5. Which movement decreases the angle of a joint?
   1. A. Extension
   2. B. Abduction
   3. C. Flexion
   4. D. Rotation
6. What defines the boundaries of a sarcomere?
   1. A. M lines
   2. B. A bands
   3. C. Z lines
   4. D. I bands
7. Which action involves moving a limb away from the midline of the body?
   1. A. Adduction
   2. B. Flexion
   3. C. Extension
   4. D. Abduction