krit.club logo

Human Body Systems - Nutrients and Malnutrition

Grade 7IB

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

🔑Concepts

•

Nutrients are chemical substances in food that provide energy, structural materials, and regulating agents for growth, maintenance, and repair. The seven classes are: Carbohydrates, Proteins, Lipids (Fats), Vitamins, Minerals, Fiber, and Water.

•

Carbohydrates are the body's primary energy source. Simple carbohydrates like Glucose (C6H12O6C_6H_{12}O_6) provide immediate energy, while complex carbohydrates like Starch must be broken down.

•

Proteins are polymers of amino acids used for growth, tissue repair, and making enzymes. A lack of protein can lead to Kwashiorkor.

•

Lipids (Fats and Oils) provide long-term energy storage and insulation. They contain more energy per gram than carbohydrates, approximately 37 kJ/g37 \text{ kJ/g} compared to 17 kJ/g17 \text{ kJ/g}.

•

Micronutrients include Vitamins (e.g., Vitamin CC for skin/immune health) and Minerals (e.g., Iron or FeFe for hemoglobin, Calcium or CaCa for bone strength).

•

Malnutrition refers to an unbalanced diet. This includes under-nutrition (deficiency of calories or specific nutrients) and over-nutrition (excessive intake, leading to obesity and Type 2 diabetes).

•

Specific Deficiency Diseases: Scurvy (lack of Vitamin CC), Rickets (lack of Vitamin DD or CaCa), Anemia (lack of FeFe), and Goitre (lack of Iodine or II).

📐Formulae

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

Q=m×c×ΔTQ = m \times c \times \Delta T

Energy per gram (J/g)=Mass of water (g)×4.2×Temperature change (°C)Mass of food (g)\text{Energy per gram (J/g)} = \frac{\text{Mass of water (g)} \times 4.2 \times \text{Temperature change (°C)}}{\text{Mass of food (g)}}

💡Examples

Problem 1:

A student weighs 60 kg60 \text{ kg} and is 1.5 m1.5 \text{ m} tall. Calculate their Body Mass Index (BMIBMI) and determine if they fall within the healthy range (18.5−24.918.5 - 24.9).

Solution:

BMI=601.52=602.25=26.67 kg/m2BMI = \frac{60}{1.5^2} = \frac{60}{2.25} = 26.67 \text{ kg/m}^2

Explanation:

Using the formula BMI=massheight2BMI = \frac{\text{mass}}{\text{height}^2}, we find the value is 26.6726.67. Since this is greater than 24.924.9, the individual is classified as overweight.

Problem 2:

During a calorimetry experiment, 0.5 g0.5 \text{ g} of a nut is burned to heat 20 g20 \text{ g} of water. The temperature of the water rises from 20∘C20^{\circ}C to 50∘C50^{\circ}C. Calculate the energy released per gram of the nut in Joules (J/gJ/g). Use c=4.2 J/g∘Cc = 4.2 \text{ J/g}^{\circ}C.

Solution:

Q=20×4.2×(50−20)0.5=20×4.2×300.5=25200.5=5040 J/gQ = \frac{20 \times 4.2 \times (50 - 20)}{0.5} = \frac{20 \times 4.2 \times 30}{0.5} = \frac{2520}{0.5} = 5040 \text{ J/g}

Explanation:

The energy absorbed by the water is calculated using mcΔTmc\Delta T, which is 2520 J2520 \text{ J}. Dividing this by the mass of the food (0.5 g0.5 \text{ g}) gives the energy content per gram.

Problem 3:

Identify the deficiency disease: A patient presents with swollen, bleeding gums and poor wound healing. Which nutrient is missing from their diet?

Solution:

The patient is likely suffering from Scurvy, caused by a deficiency in Vitamin CC (Ascorbic Acid).

Explanation:

Vitamin CC is essential for the synthesis of collagen. Without it, connective tissues weaken, leading to the symptoms described.

Nutrients and Malnutrition - Revision Notes & Key Formulas | IB Grade 7 Science