Biology paper 1

• Types of cells


  • Animal cells
  • Plant cells
• Organelles in both animal and plant cells

  • Nucleus
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Cell membrane
• Plant cells


  • Vacuole
  • Cell wall made of cellulose
  • Chloroplasts
• Eukaryotic cells


  Cells with DNA inside a nucleus
• Prokaryotic cells


  Cells with DNA not in a nucleus, like bacteria
• Mitosis


  1. Chromosomes copied

  2. Chromosomes line up in middle

  3. Chromosomes pulled apart

  4. Daughter nuclei formed
• Humans have 23 pairs of chromosomes (46 total)
• Meiosis


  1. DNA copied

  2. Chromosomes swap information

  3. Two daughter nuclei formed

  4. Four gametes formed with half the information
• Stem cells


  Cells that can become specialised
• Magnification


  Image size / Object size
• Nanometers


  1 million times smaller than millimeters
• Micrometers


  1 thousand times smaller than millimeters
• Light microscopes


  • Can see cells but not individual organelles
• Electron microscopes


  • Can see individual organelles with better resolution
• DNA


  Made of 4 bases: A, T, C, G
• Triplets of DNA bases


  Code for amino acids that make up proteins
• Genes


  Long sequences of DNA triplets that code for specific traits
• Diffusion


  Movement of particles from high to low concentration, no energy needed
• Osmosis


  Diffusion of water through a semi-permeable membrane
• Osmosis practical


  Weigh potato cylinders before and after soaking in sucrose solutions
• Active transport


  Movement of molecules against concentration gradient, requires energy
• Respiration


  Reaction converting glucose and oxygen into water and carbon dioxide, releases energy
• Respiration is the most important reaction in biology
• Respiration


  Similar to combustion, a slow 'burning' of glucose
• Photosynthesis


  Reaction converting carbon dioxide and water into glucose using sunlight energy
• Starch test


  Iodine turns purple when applied to starch
• Photosynthesis rate practical


  Measure oxygen bubbles produced by pond weed under different light intensities
• Photosynthesis rate


  Increases with light intensity until a limiting factor is reached
• Anaerobic respiration


  Respiration without oxygen, produces lactic acid
• Exercise


  Increases heart rate and breathing rate to supply more oxygen
• Metabolism


  Sum of all chemical reactions in the body
• Pathogens


  • Bacteria
  • Viruses
  • Fungi
  • Protists
• Defences against pathogens


  • Skin
  • Platelets
  • Cilia
  • Mucus
  • Stomach acid
• White blood cells


  • Phagocytes
  • Lymphocytes
• Antibodies


  Bind to antigens on pathogens, make them clump together
• Immunity


  Body remembers how to make antibodies for a pathogen
• Alexander Fleming discovered penicillin, the first antibiotic
• Antibiotic resistance


  Bacteria can mutate to become resistant to antibiotics
• Drug development


  1. Discovery

  2. Development

  3. Trials (animal, human, blind, double-blind)

  4. Manufacture

  5. Review
• Antibiotic testing practical


  Spread bacteria on agar plate, add antibiotic discs, measure inhibition zones