Nutrition True/False

Nutrition and Food

• Food is essential for energy, growth, and reproduction in all living organisms.
• Requirements include energy for heat and chemical reactions, building materials for cell maintenance, and control of cellular chemical processes.
• A balanced diet: 2/3 carbohydrates, 1/6 protein, 1/6 fat, along with minerals, vitamins, and water.
• Energy value: 1 kcal = 4.2 kJ; composition of macronutrients provides varying energy: carbohydrates (16 kJ/g), proteins (17 kJ/g), fats (38 kJ/g), alcohol (29 kJ/g).
• Daily caloric needs vary by age, activity level, gender, and life stage; recommended allowances: 9600 kJ for girls and 12600 kJ for boys at age 16.
• Cold climates increase energy needs for body temperature maintenance.

Chemical Composition of Food

• Nutrients are categorized into three groups:
  • Macronutrients: Needed in large amounts (C, H, N, O, P, S).
  • Micronutrients: Required in small amounts (Na, Mg, Cl, K, Ca).
  • Trace Elements: Needed in very tiny amounts (Fe, Cu, Zn).

Carbohydrates

• Composed of simple sugars; general formula: (CH2O)n.
• Types:
  • Monosaccharides (single units),
  • Disaccharides (two units),
  • Polysaccharides (many units).
• Functions: Quick energy source, dietary fiber for digestion, energy storage (glycogen in animals, starch in plants), and structural components (cellulose in plants).

Lipids

• Basic unit: triglycerides (1 glycerol + 3 fatty acids).
• Forms:
  • Fats (solid, saturated) linked to high cholesterol and health risks.
  • Oils (liquid, unsaturated) generally healthier.
• Functions: Concentrated energy storage, structural role in cell membranes as phospholipids, and protection of organs and insulation.

Proteins

• Comprised of amino acids; 20 different amino acids create unique proteins.
• Types:
  • Structural proteins (e.g., collagen, keratin),
  • Physiological proteins (e.g., enzymes, hormones).
• Essential amino acids must be obtained from diet; non-essential can be synthesized.

Vitamins

• Required in small amounts for cell function and health; two types:
  • Fat-soluble (A, D, E, K) stored in the liver.
  • Water-soluble (C, B) not stored, need regular intake.
• Common deficiencies:
  • Vitamin A: night blindness.
  • Vitamin B complex: beriberi, pellagra.
  • Vitamin C: scurvy.
  • Vitamin D: rickets, osteomalacia.

Minerals

• absorbed as ions; vital for various body functions.
• Common minerals:
  • Calcium (bones, teeth) - deficiency leads to osteoporosis.
  • Magnesium (bones, nerve/muscle function) - deficiency leads to weakness.
  • Iron (hemoglobin) - deficiency causes anemia.

Importance of Water

• Essential for life, providing solvents for chemical reactions.
• Functions:
  • Transport medium for nutrients and waste.
  • Major component of body fluids, aiding in reactions.
  • Regulates body temperature through high heat capacity.

Energy Transfer Reactions

• Catabolic reactions break down molecules and release energy (e.g., respiration).
• Anabolic reactions use energy to build complex molecules (e.g., protein synthesis).
• Energy is stored in ATP and transported within cells.

Practical Activities

• Starch test: iodine turns blue-black in the presence of starch.
• Reducing sugar test: Benedict’s solution turns orange/red with glucose.
• Lipid test: fat leaves a permanent translucent stain on brown paper.
• Protein test: Biuret solution changes from blue to purple indicating protein presence.