Leaving Cert Biology: Topic of Food

Exam Layout Overview for 2024

• Section A: Short Answer Questions
  • 7 questions (was 6), answer 5
  • Each question: 20 marks
  • Total: 100 marks
• Section B: Experiment Questions
  • 3 questions, answer 2
  • Each question: 30 marks
  • Total: 60 marks
• Section C: Long Answer Questions
  • 7 questions (was 6), answer 4
  • Each question: 60 marks
  • Total: 240 marks
• Overall Total: 400 marks

Importance of Food in Unit 1

• Food is part of Unit 1 with scientific method and ecology
• Likely to appear in short answer questions
• Two short questions from Unit 1
• Possible experiment question on food tests
• Interrelated with other topics (e.g., cell structure)

The Need for Food

• Nutrition: How organisms obtain and use food
• Nutrients Needed: Minerals, carbohydrates, fats, vitamins, water, proteins
• Reasons for Food:
  • Energy
  • Growth and repair of cells/muscles
  • Chemicals for cellular/metabolic reactions

Food Components

• Main Biomolecules:
  • Carbohydrates
  • Lipids
  • Proteins
  • Vitamins

Carbohydrates

• Elements: Carbon, Hydrogen, Oxygen
• General Formula: Cx(H2O)y
• Types:
  • Monosaccharides: Single sugar units (e.g., glucose)
  • Disaccharides: Two sugar units (e.g., maltose)
  • Polysaccharides: Many sugar units (e.g., starch, glycogen)
• Functions:
  • Structural: Cellulose for plant cell walls
  • Metabolic: Energy source in respiration
• Sources: Bread, potatoes, rice, pasta, fruits

Lipids

• Types: Fats (solid) and oils (liquid)
• Components:
  • Triglycerides (3 fatty acids + glycerol)
  • Phospholipids (2 fatty acids + phosphate)
• Functions:
  • Structural: Cell membranes
  • Energy storage
• Sources: Butter, oils, cream, fried foods

Proteins

• Elements: CHON (sometimes sulfur/phosphorus)
• Structure: Composed of amino acids
• Types:
  • Fibrous Proteins: Structural (e.g., keratin)
  • Globular Proteins: Functional, enzymes (e.g., amylase)
• Functions:
  • Structural: Muscles, keratin
  • Metabolic: Enzymes, antibodies
• Sources: Meat, fish, eggs, nuts

Vitamins

• Types:
  • Water-Soluble: Vitamin C
  • Fat-Soluble: Vitamin D
• Sources:
  • Vitamin C: Citrus fruits, vegetables
  • Vitamin D: Cod liver oil, milk
• Deficiency Diseases:
  • Vitamin C: Scurvy
  • Vitamin D: Rickets, osteomalacia

Minerals

• Needed in small amounts for body structure and fluid balance
• Examples:
  • Plants: Magnesium (chlorophyll), Calcium (cell walls)
  • Animals: Iron (hemoglobin), Calcium (bones, teeth)

Water

• Essential for all living organisms
• Functions:
  • Solvent
  • Temperature regulation
  • Metabolic reactions

Food Tests

• Reducing Sugar (Glucose): Benedict’s solution turns brick red
• Starch: Iodine turns blue-black
• Protein: Biuret solution turns purple
• Lipids: Brown paper test leaves a translucent mark

Resources

• Exam revision website offers:
  • Video tutorials
  • Quizzes
  • Notes
  • Exam question builders
• Available for multiple subjects, beneficial for comprehensive study.