Question

Which of the following is present in teeth?

• A. Protein
• B. Calcium
• C. Carbohydrate
• D. Minerals

Hint:

Recall the specific mineral, combined with phosphate, that hardens tooth enamel and bone.

Answer 1

The Correct Option is B

Step 1: Understanding the Question.
The question asks which substance among protein, calcium, carbohydrate and minerals makes up teeth. This is a basic fact about the composition of hard tissues in the body.

Step 2: Key Formula or Approach.
Teeth are hard structures built mainly of a mineral compound called calcium hydroxyapatite, which is a combination of calcium and phosphate. This mineral gives teeth (and bones) their hardness and strength. The enamel, the hardest outer layer of the tooth, is especially rich in this calcium compound.

Step 3: Detailed Explanation.
Protein forms soft tissues like muscle, skin and enzymes; it is present in the body in large amounts but is not the main substance that hardens teeth.
Carbohydrate mainly supplies energy to cells and is not built into the hard structure of teeth.
Minerals is a broad, general term for many different elements the body needs, such as calcium, iron, iodine and zinc; it does not name the specific substance responsible for hardening teeth.
Calcium, combined with phosphate as hydroxyapatite crystals, is deposited in the enamel and dentin layers of the tooth, giving teeth their strength and rigidity. Since the question asks for the specific substance, calcium is the precise and correct answer.

Step 4: Final Answer.
Teeth are hardened mainly by calcium in the form of calcium hydroxyapatite.
\[ \boxed{\text{Calcium}} \]