Gl Revision

• Characteristics of living organisms

  • Require nutrition
  • Respire
  • Excrete waste
  • Respond to surroundings
  • Move
  • Control internal conditions
  • Reproduce
  • Grow and develop
• Eukaryotic organisms


  • Plants: multicellular, contain chloroplasts, carry out photosynthesis, have cellulose cell walls, store carbohydrates as starch or sucrose
  • Animals: multicellular, do not contain chloroplasts, cannot carry out photosynthesis, no cell walls, have nervous coordination and can move, store carbohydrates as glycogen
  • Fungi: not able to carry out photosynthesis, body organised into mycelium of hyphae, some single-celled, cell walls made of chitin, feed by extracellular secretion of digestive enzymes and absorption, store carbohydrates as glycogen
  • Protoctists: microscopic single-celled organisms, some have features of animal cells, others have chloroplasts and are more like plants
• Prokaryotic organisms (bacteria)


  • Microscopic single-celled organisms, have cell wall, cell membrane, cytoplasm and plasmids, lack a nucleus but contain circular DNA, some can carry out photosynthesis but most feed off other living or dead organisms
• Pathogen


  Fungi, bacteria, protoctists and viruses that can cause disease
• Viruses


  Small parasitic particles that can only reproduce inside living cells, have a protein coat and contain DNA or RNA
• Levels of organisation in organisms

  • Organelles
  • Cells
  • Tissues
  • Organs
  • Systems
• Cell structures


  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Mitochondria
  • Chloroplasts
  • Ribosomes
  • Vacuole
• Functions of cell structures

  Nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes, vacuole
• Similarities and differences in structure of plant and animal cells
• Chemical elements present in biological molecules

  • Carbohydrates
  • Proteins
  • Lipids (fats and oils)
• Structure of biological molecules

  Carbohydrates: large molecules made up of simple sugars

  Proteins: large molecules made up of amino acids

  Lipids: large molecules made up of fatty acids and glycerol
• Investigating food samples


  Test for presence of glucose, starch, protein, fat
• Enzymes


  Biological catalysts that speed up metabolic reactions
• Temperature changes


  Affect enzyme function, including changes to the shape of the active site
• Investigating enzyme activity


  Effect of temperature changes
• Changes in pH


  Affect enzyme function by altering the active site
• Diffusion, osmosis, active transport


  Processes by which substances move into and out of cells
• Factors affecting rate of movement into/out of cells


  Surface area to volume ratio, distance, temperature, concentration gradient
• Investigating diffusion and osmosis


  Using living and non-living systems
• Photosynthesis


  Process of converting light energy to chemical energy
• Photosynthesis equation


  Word equation and balanced chemical symbol equation
• Factors affecting rate of photosynthesis

  Carbon dioxide concentration, light intensity, temperature
• Leaf structure


  • Adapted for photosynthesis
• Mineral ions required by plants

  Magnesium for chlorophyll, nitrate for amino acids
• Investigating photosynthesis


  Showing evolution of oxygen, production of starch, requirements of light, carbon dioxide, chlorophyll
• Components of a balanced human diet

  • Carbohydrates
  • Proteins
  • Lipids (fats and oils)
  • Vitamins
  • Minerals
  • Water
  • Dietary fibre
• Sources and functions of diet components

  Carbohydrates, proteins, lipids, vitamins A/C/D, calcium, iron, water, dietary fibre
• Energy requirements


  Vary with activity levels, age, pregnancy
• Structure and function of human alimentary canal

  • Mouth, oesophagus, stomach, small intestine (duodenum, ileum), large intestine (colon, rectum), pancreas
• Peristalsis


  Movement of food through the gut
• Digestive enzymes


  Amylase and maltase digest starch to glucose, proteases digest proteins to amino acids, lipases digest lipids to fatty acids and glycerol
• Role of digestive enzymes
• Components of a balanced diet

  • Carbohydrate
  • Protein
  • Lipid
  • Vitamins
  • Minerals
  • Water
  • Dietary fibre
• Carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, calcium, iron, water, dietary fibre


  Sources and functions as components of the diet
• Energy requirements vary with activity levels, age and pregnancy
• Structure and function of the human alimentary canal

  1. Mouth

  2. Oesophagus

  3. Stomach

  4. Small intestine (duodenum and ileum)

  5. Large intestine (colon and rectum)

  6. Pancreas
• Food is moved through the gut by peristalsis
• Role of digestive enzymes

  1. Digestion of starch to glucose by amylase and maltase

  2. Digestion of proteins to amino acids by proteases

  3. Digestion of lipids to fatty acids and glycerol by lipases
• Bile is produced by the liver and stored in the gall bladder
• Role of bile


  Neutralising stomach acid and emulsifying lipids