​Important functions of calcium are​

Correct option is D

Calcium plays several crucial roles in the body, including bone formation, blood coagulation, and maintaining membrane permeability. These are all vital functions that calcium is involved in:

1. Formation of bone: Calcium is the primary mineral in bones and teeth, contributing to their strength and structure. It is stored in the bones and is released into the bloodstream when needed to maintain normal body functions.
2. Blood coagulation: Calcium is essential for blood clotting. It is involved in the coagulation cascade, which is the process that helps blood to clot and prevent excessive bleeding after injury.
3. Membrane permeability: Calcium ions help regulate the permeability of cell membranes and are involved in signal transmission across the membranes, including muscle contraction and nerve function.

Information Booster:

• Bone formation: Calcium provides structural support in bones and teeth by combining with phosphorus to form hydroxyapatite, which gives bones their rigidity. Adequate calcium intake is vital for bone development, especially during growth periods like childhood and adolescence, and for maintaining bone density in adults.
• Blood coagulation: Calcium is involved in the blood clotting process by acting as a cofactor in several steps of the coagulation cascade. Without calcium, the clotting process would be impaired, leading to excessive bleeding.
• Membrane permeability: Calcium helps in maintaining the proper functioning of cell membranes by regulating the passage of substances in and out of cells. It plays a role in muscle contraction, nerve signaling, and the release of hormones and neurotransmitters.

Additional Knowledge (Incorrect Options):

• (a) Formation of bone: This is correct, but calcium's role extends beyond just bone formation. It also plays a role in other bodily functions like blood coagulation and membrane permeability.
• (b) Blood coagulation: This is also correct. Calcium is an essential element in the blood clotting mechanism.
• (c) Membrane permeability: This is correct too. Calcium helps regulate cell membrane functions, especially in muscles and nerves.
• (e) None of the above: This is incorrect because calcium is indeed involved in all of these processes—bone formation, blood coagulation, and membrane permeability.