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Human Body Systems - Nutrition and Healthy Growth

Grade 3IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

A balanced diet provides the body with necessary nutrients for growth and repair. It includes five main groups: Carbohydrates, Proteins, Fats, Vitamins, and Minerals.

Energy is required for all bodily functions and is measured in kilocalories (kcalkcal) or kilojoules (kJkJ).

Carbohydrates like glucose (C6H12O6C_6H_{12}O_6) are the primary source of immediate energy for the body.

Proteins are made of chains of amino acids and are essential for building and repairing muscle and tissues.

Minerals such as Calcium (CaCa) are vital for strong bones, while Iron (FeFe) is necessary for healthy blood to carry oxygen (O2O_2).

Water (H2OH_2O) makes up about 60%70%60\% - 70\% of the human body and is essential for transporting nutrients and removing waste.

Healthy growth requires a combination of a balanced diet, regular physical activity, and sufficient sleep.

📐Formulae

EnergyBalance=EnergyIntakeEnergyOutputEnergy_{Balance} = Energy_{Intake} - Energy_{Output}

H2O (Water)H_2O \text{ (Water)}

C6H12O6 (Glucose/Sugar)C_6H_{12}O_6 \text{ (Glucose/Sugar)}

Ca+Vitamin DStrong BonesCa + Vitamin\ D \rightarrow Strong\ Bones

💡Examples

Problem 1:

If a child consumes 1800 kcal1800\ kcal of food in a day and uses 1800 kcal1800\ kcal through exercise and body functions, what is their energy balance?

Solution:

1800 kcal1800 kcal=0 kcal1800\ kcal - 1800\ kcal = 0\ kcal

Explanation:

The child is in a state of energy balance. Their weight will likely remain stable because the energy consumed equals the energy expended.

Problem 2:

Why is it important to include Calcium (CaCa) in a Grade 3 student's diet?

Solution:

Calcium is used to build Ca10(PO4)6(OH)2Ca_{10}(PO_4)_6(OH)_2 (Hydroxyapatite) in bones.

Explanation:

During childhood, the body is growing rapidly. Minerals like Calcium (CaCa) are essential to ensure that the skeletal system becomes strong and dense.

Problem 3:

Identify the primary molecule the body uses for quick energy during a physical education class.

Solution:

Glucose, which has the chemical formula C6H12O6C_6H_{12}O_6.

Explanation:

Carbohydrates are broken down into simple sugars like glucose to provide the muscles with the energy needed for movement.

Nutrition and Healthy Growth - Revision Notes & Key Formulas | IB Grade 3 Science