HSB Textbook

• Acronym

  • GRIMNER for the seven life processes; growth, reproduction, irritability, movement, nutrition, excretion, respiration
• Photosynthesis


  Process by which green plants convert carbon dioxide and water into glucose by using energy from sunlight absorbed by chlorophyll in chloroplasts
• Oxygen is produced as a by-product of photosynthesis
• Photosynthesis


  1. Carbon dioxide + water

  2. Glucose + oxygen
• Photosynthesis


  • Occurs in any plant structure that contains chlorophyll
  • Mainly occurs in the leaves
• Chlorophyll


  Absorbs energy from sunlight and uses it to convert carbon dioxide and water into glucose and oxygen
• Oxygen


  Used by leaf cells in respiration, excess diffuses out of leaves into the air
• Glucose


  • Can be used by leaf cells in respiration to release energy
  • Can be converted to starch and stored
  • Can be converted to other organic substances like amino acids, protein, vitamins, chlorophyll
  • Can be converted to sucrose and transported to other parts of the plant
• Food chain


  Diagram showing the flow of food and energy from one organism to the next
• Components of a food chain

  • Producer (green plant)
  • Primary consumer (eats producer)
  • Secondary consumer (eats primary consumer)
  • Tertiary consumer (eats secondary consumer)
  • Quaternary consumer (eats tertiary consumer)
• Herbivore


  Consumes plants or plant material only
• Carnivore


  Consumes animals or animal material only
• Omnivore


  Consumes both plants and animals, or plant and animal material
• Trophic level


  The position or level that an organism occupies in a food chain
• Food chains are interrelated to form food webs
• All other living organisms depend both directly and indirectly on plants for food
• Not all the energy incorporated into organic food molecules made by green plants during photosynthesis is passed along a food chain, some is used and some is lost at each trophic level
• Humans need a variety of nutrients to provide them with energy, to enable them to grow and develop, and to keep them healthy
• Nutrients required in the human diet

  • Carbohydrates
  • Proteins
  • Lipids
  • Vitamins
  • Minerals
  • Water
  • Dietary fibre
• Macronutrients


  Carbohydrates, proteins and lipids, required in relatively large quantities
• Micronutrients


  Vitamins and minerals, required in relatively small quantities
• Carbohydrates


  Molecules composed of carbon, hydrogen and oxygen atoms, with a ratio of hydrogen to oxygen of 2:1
• Types of carbohydrates


  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• Monosaccharides


  Simplest carbohydrate molecules, have the formula C6H12O6, all are reducing sugars
• Disaccharides


  Formed by chemically joining two monosaccharide molecules, have the formula C12H22O11, all are reducing sugars except sucrose which is non-reducing
• Polysaccharides


  Formed by joining many monosaccharide molecules into straight or branched chains, include starch, cellulose and glycogen
• Carbohydrates include reducing sugars, non-reducing sugars and starch
• Properties of different carbohydrates

  • Reducing sugars: sweet taste, soluble in water, react with Benedict's solution
  • Non-reducing sugars: sweet taste, soluble in water, do not react with Benedict's solution
  • Starch: no sweet taste, insoluble in water, reacts with iodine solution
• Proteins


  Molecules composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur and phosphorus atoms, formed by joining amino acids into long chains
• Proteins


  • Their chemical structure can be changed by heat or certain other chemicals (denatured)
  • Some are globular and soluble in water, others are fibrous and insoluble
  • They react with biuret reagent
• Lipids


  Fats and oils, molecules composed of carbon, hydrogen and oxygen atoms, with fewer oxygen atoms than carbohydrates, made up of three fatty acid molecules and one glycerol molecule
• Amino acids


  Small molecules formed from carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur and phosphorus atoms
• Protein molecules


  Formed by joining hundreds or thousands of amino acid molecules together in long chains
• Proteins


  • Their chemical structure can be changed by heat or certain other chemicals, i.e. they can be denatured
  • Some are globular in structure and are soluble in water, e.g. haemoglobin and albumen, others are fibrous and are insoluble, e.g. collagen and keratin
  • They react with biuret reagent
• Lipids


  Fats and oils, molecules composed of carbon, hydrogen and oxygen atoms with fewer oxygen atoms than carbohydrate molecules
• Lipid molecule


  Made up of three fatty acid molecules and one glycerol molecule
• Lipids


  • Feel greasy, are insoluble in water and they leave a grease spot on paper
• Laboratory tests to identify carbohydrates, proteins and lipids

  1. Add Benedict's solution, heat

  2. Add hydrochloric acid, heat, add sodium hydrogencarbonate, add Benedict's solution, heat

  3. Add iodine solution

  4. Add sodium hydroxide solution, add copper sulfate solution or biuret reagent

  5. Add ethanol, shake, add water, shake

  6. Rub on absorbent paper, leave for 10 minutes
• Reducing sugars


  Form an orange-red precipitate with Benedict's solution
• Starch


  Turns iodine solution blue-black