Biology Notes: Food

Page 1

• Subject: Biology

• Teacher: Ms. R. Doyle

• Course: 5th/6th Year

• Academic Level: Higher

• Academic Year: 24/25

• Topic: Food

Page 2

Contents

• Definitions: Page 1

• Categories: Page 2

• Carbohydrates (in detail): Page 4

• Revision Questions: Page 5

• Exam Paper Questions: Page 7

Page 3

Definitions

• Amino Acid: Subunit of a protein (C, H, O, N; may contain S and P).

• Anabolic Reaction: Energy-requiring reaction forming complex molecules (e.g., photosynthesis).

• Antibody: Protein produced in response to pathogens.

• Balanced Diet: Correct proportions of food groups.

• Catabolic Reaction: Energy-releasing reaction breaking down complex molecules (e.g., respiration).

• Disaccharide: Two sugar units (e.g., maltose).

• Enzyme: Biological catalyst (protein).

• Excretion: Removal of metabolic waste.

• Fat Soluble Vitamin: Vitamins that do not dissolve in water (e.g., vitamin D).

• Fat: Solid lipid at room temperature.

• Haemoglobin: Oxygen-carrying protein in blood.

• Hormone: Protein carrying chemical messages in the body.

• Metabolism: Sum of all chemical reactions in an organism.

• Monosaccharide: Single sugar unit (e.g., glucose).

• Oil: Liquid lipid at room temperature.

• Phospholipid: Lipid with a phosphate replacing one fatty acid.

• Polysaccharide: More than two sugar units.

• Trace Element: Mineral required in small amounts (e.g., Iron).

• Triglyceride: Lipid subunit (glycerol + fatty acids).

• Water Soluble Vitamin: Vitamins that dissolve in water (e.g., vitamin C).

Page 4

Categories of Food

1. Carbohydrates

   • Elements: C, H, O

   • Sources: Potatoes, bread, pasta

   • Subunit: Monosaccharide (e.g., glucose)

2. Proteins

   • Elements: C, H, O, N (S and P sometimes)

   • Sources: Meat, fish, eggs, seeds

   • Subunit: Amino acids

3. Lipids

   • Elements: C, H, O

   • Sources: Butter, nuts

   • Subunit: Triglyceride

4. Vitamins

   • Fat-soluble: A, D, K

   • Water-soluble: B, C

5. Minerals

   • Major: Ca (animals), Mg (plants), Na

   • Trace Elements: Iron, Copper, Zinc

6. Water

   • Composition: H, O

Page 5

Functions of Food Categories

• Carbohydrates:

  • Structural: Cellulose (plant cell walls), Chitin (animal exoskeleton)

  • Energy Storage: Starch (plants), Glycogen (animals)

• Proteins:

  • Structural: Cell membranes, muscle (myosin), skin/hair/nails (keratin)

  • Metabolic: Enzymes, haemoglobin, antibodies, hormones

• Lipids:

  • Structural: Phospholipids in cell membranes, protective layers, insulation

  • Metabolic: Energy storage and release

• Vitamins:

  • Vitamin D: Calcium absorption

  • Vitamin C: Iron absorption, connective tissue formation

• Minerals:

  • Calcium: Bone formation (animals), cell wall (plants)

  • Iron: Haemoglobin formation (animals)

  • Magnesium: Chlorophyll formation (plants)

• Water:

  • Solvent, temperature regulation, medium for reactions, transport

Page 6

Tests/Experiments

• Starch: Iodine test (brown to blue-black)

• Reducing Sugar: Benedict's solution (blue to brick red)

• Protein: Biuret test (blue to purple)

• Fat: Brown paper test (permanent translucent stain)

Categories of Carbohydrates

1. Monosaccharides: Single sugar units (e.g., glucose)

2. Disaccharides: Two sugar units (e.g., maltose, sucrose)

3. Polysaccharides: More than two sugar units (e.g., cellulose, starch, glycogen)

Reactions

• Catabolic Reaction: Energy release from breaking down complex molecules (e.g., respiration).

• Anabolic Reaction: Energy requirement for forming complex molecules (e.g., photosynthesis).

Page 7

Revision Questions

1. Elements in carbohydrates and lipids?

2. Define monosaccharide and give an example.

3. Define disaccharide and give an example.

4. Name two polysaccharides in animals (structural and energy storage).

5. What type of saccharide is cellulose?

6. Where is cellulose found in the cell?

7. Function of cellulose in the cell?

8. Difference between carbohydrates and lipids?

9. General chemical formula for carbohydrates?

10. Ratio of carbon to hydrogen in carbohydrates?

11. Chemicals to test for reducing sugar?

12. Positive result for reducing sugar?

13. Chemical for starch test?

14. Positive result for starch?

15. Element in proteins not in carbohydrates or lipids?

16. Protein subunit name?

17. Examples of proteins in the body?

18. Test for protein presence?

19. Chemicals for protein test?

20. Is heat required for reducing sugar test?

21. Positive result for protein?

22. Structural protein example?

23. Difference between fat and oil?

24. What is a triglyceride?

25. Draw triglyceride structure.

26. Difference between lipid and phospholipid?

27. Function of fat in the body?

28. Where are lipids found in the cell?

29. Function of lipid in a cell?

30. Positive result for lipids using brown paper?

31. Categories of vitamins and examples?

32. Role of Vitamin D?

33. Food containing Vitamin D?

34. Deficiency disease for Vitamin D?

35. Role of Vitamin C?

36. Food containing Vitamin C?

37. Deficiency diseases for Vitamin C?

38. Explain trace elements.

39. Example of trace elements in diet?

40. Role of iron and calcium in diet?

41. Role of magnesium in plants?

42. Deficiency disease for iron?

43. Deficiency disease for calcium?

44. Deficiency disease for magnesium in plants?

45. Functions of water in the body?

46. Explain catabolic reaction.

47. Example of catabolic reaction.

48. Explain anabolic reaction.

49. Example of anabolic reaction.

50. Control experiment results for lipid test?

51. Control experiment results for protein test?

52. Control experiment results for reducing sugar test?

53. Control experiment results for starch test?

54. Elements sometimes found in proteins?

Page 8-16

Exam Paper Questions

• Various questions from previous years focusing on definitions, functions, tests, and comparisons of biomolecules.

This note summarizes the key concepts and definitions related to food in biology, structured for easy reference and study.