Assertion : There are similarities between the locomotion of unicellular organisms and multicellular animals.
Reason : Ciliary, flagellar and amoeboid movements occur in unicellular organisms
Assertion: Muscle fibre is a syncitium.
Reason: Muscle fibre has a large number of parallelly arranged myofilaments in the sarcoplasm.
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Assertion: Visceral muscles are smooth in appearance.
Reason: Many muscle cells assemble in a branching pattern to form a visceral muscle.
Assertion: Locomotion in Hydra is carried out by two types of contractile cells.
Reason: Muscle fibres are lacking in Hydra.
Assertion: The portion of the myofibril between two successive 'Z' lines is considered as the functional unit of contraction called sarcomere.
Reason: During contraction, 'I' bands get reduced whereas 'A' bands retain the length, thereby causing shortening of the sarcomere.
Assertion : Extra oxygen consumption in human body is known as oxygen debt.
Reason : The extra oxygen is required by the body to oxidise the accumulated lactic acid produced during strenous exercise.
Assertion : Biceps and triceps are called antagonistic muscles.
Reason : This is due to the fact that they contract and relax together.
Assertion : Muscle contraction force increases with rise in strength of stimulus.
Reason : This is due to increased contraction of individual muscle fibres with increase in stimulus strength.
Assertion: Fatigue is inability of muscle to relax.
Reason: It is due to lactic acid accumulation by repeated contractions.
Assertion : The phase of muscle contraction occurs when myosin binds and releases actin.
Reason : Muscle contraction is initiated by a signal sent by the peripheral nervous system via motor neuron.
Assertion: Mechanism of muscle contraction is explained by sliding-filament theory.
Reason: Contraction of muscle fibre takes place by the sliding of thick filaments over the thin filaments
Assertion: On stimulation, a muscle cell releases calcium ions (Ca2+) from sarcoplasmic reticulum.
Reason: By reacting with a protein complex, Ca2+ uncover active sites on the actin filaments.
Assertion: A person becomes fatigue very soon during exercise.
Reason: Muscle fibres undergo oxygen debt during exercise.
Assertion: Red muscles depend on anaerobic process for energy.
Reason: Red muscles have few number of mitochondria in them.
Assertion: Rapid spasm in muscle is termed as tetany.
Reason: Tetany is usually caused by an increase in the blood calcium level.
Assertion: Human has dicondylic skull.
Reason: Skull articulates with superior region of the vertebral column with the help of two occipital condyles.
Assertion: Radius is shorter than ulna.
Reason: It has large olecranon process
Assertion: Bone has very hard matrix whereas cartilage has pliable matrix.
Reason: Bone has calcium salts in its matrix whereas cartilage has chondroitin salts in its matrix.
Assertion: First seven pairs of ribs are called true ribs.
Reason: These ribs are not connected ventrally to the sternum.
Assertion : Ball and socket joints are the most mobile joints.
Reason : Synovial fluid is present here.
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