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True or False?
All living organisms are capable of moving from place to place, such as the majority of plant species.
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True or False?
All living organisms are capable of moving from place to place, such as the majority of plant species.
False.
Some living organisms are sessile and cannot move from place to place.
Define the term "motile".
Motile refers to the ability of an organism to move from one place to another.
What is the main difference between motile and sessile organisms?
Motile organisms can move from place to place, while sessile organisms cannot move from their fixed location but can move parts of their body.
Give examples of sessile organisms.
Examples of sessile organisms include sponges, corals, anemones, and all plant species.
True or False?
Sessile organisms never exhibit any type of movement.
False.
All living organisms exhibit movement. This is part of the MRS GREN system of classifying living organisms.
What type of movement can sessile organisms exhibit?
Sessile organisms can move parts of themselves in response to environmental stimuli, such as the orientation of plant stems towards the sun or the movement of cytoplasm within a unicellular organism.
What is the main type of muscle that aids movement and is attached to the skeleton?
Skeletal muscle is the type of muscle that is attached to the skeleton and aids movement.
What is the appearance of skeletal muscle when viewed under a microscope?
Skeletal muscle is striated, meaning it has a stripy appearance when viewed under a microscope.
What are the two main types of protein filaments that make up a myofibril?
The two main types of protein filaments in a myofibril are thick filaments made of myosin and thin filaments made of actin.
Define the term "myofibril".
Myofibrils are bundles of actin and myosin filaments that slide past each other during muscle contraction.
What is the function of the sarcoplasmic reticulum (SR) in muscle fibres?
The sarcoplasmic reticulum stores calcium and conveys signals to all parts of the muscle fibre using protein pumps in the membranes.
What is the role of mitochondria in muscle fibres?
The mitochondria in muscle fibres carry out aerobic respiration to generate the ATP required for muscle contraction.
Describe the structure of a sarcomere.
A sarcomere is the section of a myofibril between two Z lines, and it contains the overlapping actin and myosin filaments.
What is the "sliding filament model" of muscle contraction?
The sliding filament model states that during muscle contraction, the myosin heads form cross-bridges with the actin filaments, and the myosin heads then change orientation to pull the actin filaments, causing the sarcomeres to shorten.
True or False?
Muscles can both contract and push.
False.
Muscles can only contract and pull; they cannot push.
What is the role of the protein titin in muscle contraction and relaxation?
Titin is a large protein that joins the ends of the myosin filaments to the Z-line, and its spring-like properties aid muscle contraction and relaxation.
How does skeletal muscle contract?
Skeletal muscle contracts when it receives an impulse from a motor neurone via the neuromuscular junction.
What is a motor unit?
A motor unit consists of a motor neurone, the skeletal muscle fibres it innervates, and the neuromuscular junctions between the neurone and muscle fibres.
How does the number of activated motor units relate to the intensity of muscle contraction?
During a low-intensity muscle contraction, a low number of motor units are activated, while for a high-intensity contraction, more motor units receive impulses.
What is the primary function of the skeleton in movement?
The skeleton provides anchorage for muscles and acts as levers to facilitate effective movement of the body.
What is the difference between an endoskeleton and an exoskeleton?
An endoskeleton is an internal skeleton found in vertebrates, while an exoskeleton is an external skeleton found in organisms like arthropods.
What is the main material that arthropod exoskeletons are made of?
Arthropod exoskeletons are made of the polysaccharide chitin.
How do exoskeletons and endoskeletons facilitate movement?
Both endoskeletons and exoskeletons provide support for the body and act as levers to transfer the size and direction of muscular force.
What are the three key features of a lever system in the skeleton?
The three key features of a lever system in the skeleton are the point of effort, the point of load, and the fulcrum or pivot point.
Define the term "synovial joint".
Synovial joints are characterised by a joint cavity filled with lubricating synovial fluid, which reduces friction between the bones.
List the main types of movement possible at synovial joints.
The main types of movement possible at synovial joints are flexion, extension, rotation, abduction, and adduction.
Describe the structure of the hip joint.
The hip joint is a ball and socket synovial joint, with the femur forming the ball and the pelvis forming the socket. Cartilage and synovial fluid provide lubrication for smooth movement.
What is the role of antagonistic muscle pairs?
Antagonistic muscle pairs work in opposition to one another, with one muscle contracting to move a limb in one direction, and the other muscle contracting to move it in the opposite direction.
Give an example of antagonistic muscle action in the rib cage.
The external intercostal muscles contract to pull the ribs up and out during inhalation, while the internal intercostal muscles contract to pull the ribs down and in during exhalation.
What are the different "dimensions" or directions in which joints can move?
Joints are capable of moving in different dimensions, such as flexion, extension, rotation, abduction, and adduction.
What is a goniometer, and what is its purpose?
A goniometer is a simple tool used to measure the range of motion of a joint in degrees.
How else can the range of motion of joints be measured?
The range of motion of joints can also be measured using computer analysis or specialised mobile apps that simulate a goniometer.
What is the definition of locomotion?
Locomotion is the movement or ability to move from one place to another.
What are some examples of reasons why organisms engage in locomotion?
Examples of reasons for locomotion include foraging for food, escaping from danger, searching for a mate, and migration.
What adaptations do marine mammals have for swimming?
Marine mammals have adaptations such as streamlining of the body, development of flippers, evolution of a fluke tail for propulsion, and changes to the airways to allow for underwater breathing.
What is an example of a marine mammal that is adapted for swimming?
Examples of marine mammals adapted for swimming include dolphins and whales.
How have marine mammals evolved from their ancestral land-dwelling forms?
Marine mammals have evolved from ancestral land animals and are now capable of surviving underwater due to these adaptations.