Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• Movement is universal, but only some organisms show locomotion • Motile organisms move for food, mates, migration, or escape • Sessile organisms such as coral or plants still move body parts or grow toward stimuli
Start with the concept explanation, then practise to create mastery evidence.
Learning objective
• Sarcomeres contain actin thin filaments and myosin thick filaments between Z lines • Calcium binds troponin, moving tropomyosin away from actin binding sites • Myosin heads use ATP in a cross-bridge cycle to slide actin and shorten sarcomeres
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Learning objective
• Titin acts as a molecular spring in sarcomeres and centres myosin • Titin recoils after stretching and prevents overstretching • Antagonistic muscles are needed because muscles actively contract but do not actively extend
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Learning objective
• Motor neurons connect to skeletal muscle fibres at neuromuscular junctions • Acetylcholine release at motor end plates triggers sarcolemma excitation • Excitation releases calcium from sarcoplasmic reticulum to start contraction
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Learning objective
• Skeletons provide support, protection, muscle anchorage, and lever systems • Vertebrate endoskeletons attach muscles by tendons • Arthropod exoskeletons use chitin, joints, and internal muscle attachments
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Learning objective
• Synovial joints contain lubricating synovial fluid between cartilage-covered bones • Tendons attach muscles to bones; ligaments connect bones and stabilize joints • The hip is a ball-and-socket joint between femur and pelvis
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Learning objective
• Range of motion depends on joint type, bone surfaces, ligaments, and muscles • Ball-and-socket joints such as shoulder and hip allow circumduction • Hinge joints such as elbow and knee mainly allow flexion and extension
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Learning objective
• External and internal intercostal muscles act antagonistically during ventilation • External intercostals lift ribs up and out for inspiration • Internal intercostals pull ribs down and in during forced expiration
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Learning objective
• Locomotion allows animals to forage, avoid predators, find mates, and migrate • Examples include blackbirds feeding, hares escaping predators, orangutans finding mates, and whales migrating • Locomotion can improve survival and reproductive success
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Learning objective
• Marine mammals have streamlined bodies, reduced drag, flippers, and up-down tail flukes • Reduced pelvic bones and absent hind limbs reduce resistance in water • Cetacean blowholes allow rapid surface breathing and close during dives
Start with the concept explanation, then practise to create mastery evidence.