Answer:A. The release of calcium ions causes myosin and actin to attach to each other.
The contraction of skeletal muscles takes place by induction of a nerve impulse, which produces a movement and the interaction of the filaments containing proteins named as actin and myosin. This interaction of filaments is regulated by proteins called tropomyosin and troponin present on the actin filaments. The motor nerve causes the depolarization of the muscle membrane sarcolemma. This triggers the sarcoplasmic reticulum to release calcium ions. This calcium binds to troponin and thus allows the tropomyosine strand on the actin filament to displace so that the part of the actin where myosine head needs to be attached remain uncovered. Binding of the actin myosine filament results in contraction.
Hence, the release of calcium ions causes myosin and actin to attach to each other causes muscle contraction.
Answer:
B
Explanation:
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D. that is the correct answer
Answer:
C. Osmosis
Explanation:
Osmosis is the net movement of solvent molecules, usually water, from a region of lower solute concentration to a region of higher solute concentration through a partially permeable membrane. Osmosis is a very useful for moving materials in and out of the cell.
Solutions are mixtures of solutes and solvents. The main aim of osmosis is for all the mixture part to be uniform and the solvent equally dispersed to all the part of the solution.
Osmosis is controlled to a large extent by concentration gradient.
Diffusion on the otherhand is the movement of molecules of a substance from one position to another.
Facilitated diffusion and active transport are just mechanisms for transport within a cell or a body.
To enable primary cells to be prepared for excised tissues
