What is the main mineral that gives bones their hardness?

Iron, stored mainly in the bone marrow

Sodium, concentrated in the extracellular matrix

Magnesium, bound loosely within collagen fibres

What is the main mineral that gives…

Answer: Calcium phosphate (hydroxyapatite).

A Iron, stored mainly in the bone marrow
B Sodium, concentrated in the extracellular matrix
C Calcium phosphate (hydroxyapatite)
D Magnesium, bound loosely within collagen fibres

Correct answer: C. Calcium phosphate (hydroxyapatite)

Explanation: Bone hardness comes from calcium phosphate crystals (hydroxyapatite - Ca10(PO4)6(OH)2) deposited in a collagen protein matrix. Collagen provides flexibility; hydroxyapatite provides compressive strength. Bone is about 70% mineral and 30% organic matrix.

Structure of a sarcomere showing thick myosin filaments and thin actin filaments with the Z line, M line, A band, I band and H zone labelled

A sarcomere (Z line to Z line): during contraction the I band and H zone shorten as thin filaments slide over thick, while the A band stays the same length. Image: SlothMcCarty, CC BY-SA 3.0, via Wikimedia Commons.

Concept context

Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.

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What is the main mineral that gives bones their hardness?

Concept context

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