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Human Body Systems - Diet, Drugs, and Health

Grade 6IGCSE

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

🔑Concepts

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A balanced diet includes seven essential nutrients: Carbohydrates (CnH2nOnC_nH_{2n}O_n), Proteins, Lipids (Fats), Vitamins, Minerals, Water, and Fiber.

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Energy intake is measured in kilojoules (kJkJ) or kilocalories (kcalkcal). If energy intake exceeds energy expenditure, the excess is stored as fat.

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Deficiency diseases occur when the diet lacks specific nutrients. For example, lack of Vitamin C causes Scurvy, and lack of Iron (FeFe) causes Anemia.

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Drugs are substances that alter the chemical reactions in the body. They are categorized into medicinal drugs (e.g., antibiotics) and recreational drugs (e.g., caffeine, alcohol).

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Stimulants (e.g., Nicotine, C10H14N2C_{10}H_{14}N_2) speed up the nervous system, while Depressants (e.g., Alcohol) slow down brain activity.

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Tobacco smoke contains harmful substances: Tar (carcinogenic), Nicotine (addictive), and Carbon Monoxide (COCO), which reduces the blood's capacity to carry Oxygen (O2O_2).

📐Formulae

BMI=Mass (kg)Height2 (m2)BMI = \frac{\text{Mass (kg)}}{\text{Height}^2 \text{ (m}^2\text{)}}

Energy Balance=Energy Intake−Energy Output\text{Energy Balance} = \text{Energy Intake} - \text{Energy Output}

C6H12O6+6O2→6CO2+6H2O+EnergyC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}

💡Examples

Problem 1:

Calculate the Body Mass Index (BMI) for a student who has a mass of 50 kg50\text{ kg} and a height of 1.6 m1.6\text{ m}.

Solution:

BMI=501.62=502.56≈19.53BMI = \frac{50}{1.6^2} = \frac{50}{2.56} \approx 19.53

Explanation:

Using the BMI formula, we divide the mass by the square of the height. A BMI of 19.5319.53 falls within the healthy range of 18.518.5 to 2525.

Problem 2:

Why is Carbon Monoxide (COCO) dangerous to the human body?

Solution:

Hb+CO→HbCOHb + CO \rightarrow HbCO (Carboxyhemoglobin)

Explanation:

Carbon monoxide (COCO) binds to hemoglobin (HbHb) in red blood cells more strongly than oxygen (O2O_2). This prevents the blood from transporting sufficient oxygen to vital organs.

Problem 3:

Identify the deficiency disease caused by a lack of Vitamin D and Calcium (Ca2+Ca^{2+}).

Solution:

Rickets

Explanation:

Vitamin D and Calcium are essential for bone calcification. A lack of these leads to soft, weak bones, a condition known as Rickets in children.