Bio

• Gas exchange


  Process of taking in oxygen and giving out carbon dioxide
• Respiratory system


  • Where gas exchange occurs
• The proportions of gases in the air we inhale and exhale changes due to using oxygen in respiration and producing carbon dioxide
• What happens when you breathe in

  1. Muscles between the ribs contract

  2. Ribs are pulled up and out

  3. Diaphragm contracts and flattens

  4. Volume of the chest increases

  5. Pressure inside the chest decreases

  6. Air rushes into the lungs
• What happens when you breathe out

  1. Muscles between ribs relax

  2. Ribs are pulled in and down

  3. Diaphragm relaxes and moves up

  4. Volume in the chest decreases

  5. Pressure inside the chest increases

  6. Air is forced out of the lungs
• Enzymes


  Biological catalysts that speed up the digestion of nutrients
• Lock and key model

  The way the enzyme and nutrient bind with each other
• Types of enzymes


  • Carbohydrases (break down carbohydrates into simple sugars)
  • Proteases (break down proteins into amino acids)
  • Lipase (breaks down lipids into fatty acids and glycerol)
• Drugs


  Chemicals that affect the way our body functions
• Types of drugs


  • Medicinal drugs (used in medicine, benefit health)
  • Recreational drugs (taken for enjoyment, normally have no health benefits and can be harmful)
• Drug addiction


  When your body gets so used to a drug it feels it cannot cope without it
• Withdrawal symptoms


  Experienced when someone with an addiction stops taking the drug
• Nutrients


  • Carbohydrates (main source of energy)
  • Lipids (fats and oils, provide energy)
  • Proteins (growth and repair of cells and tissues)
  • Vitamins and minerals (essential in small amounts to keep you healthy)
  • Water (needed in all cells and body fluids)
  • Fibre (provides bulk to food to keep it moving through the gut)
• Respiration


  The process in which energy is released from the molecules of food
• Aerobic respiration


  • Involves oxygen, more efficient as all food is broken down to release energy
• Anaerobic respiration


  A type of respiration which does not use oxygen, used when the body cannot supply enough oxygen for aerobic respiration
• Anaerobic respiration releases less energy than aerobic respiration
• Lactic acid


  Produced through anaerobic respiration, can cause muscle cramps
• Oxygen debt


  When lactic acid builds up because there is not enough oxygen present in the blood supply to break it down
• Fermentation


  A type of anaerobic respiration which occurs in yeast, produces ethanol instead of lactic acid
• Plant minerals


  • Nitrates (contain nitrogen, for healthy growth)
  • Phosphates (contain phosphorus, for healthy roots)
  • Potassium (for healthy leaves and flowers)
  • Magnesium (for making chlorophyll)
• Fertilisers can be used to stop plants from suffering with mineral deficiencies
• Photosynthesis


  The process which occurs in the chloroplasts to produce glucose using sunlight, water and carbon dioxide
• Producers


  • Organisms that can use photosynthesis to produce their own food, including plants and algae
• Factors affecting rate of photosynthesis

  • Light intensity (higher intensity increases rate up to a point)
  • Carbon dioxide concentration (higher concentration increases rate up to a point)
  • Temperature (optimum temperature for highest rate, before and after this the rate is less)
• Leaf adaptations for photosynthesis

  • Thin to allow most light through
  • Lots of chlorophyll to absorb light
  • Large surface area to absorb as much light as possible
  • Waxy layer to reduce water loss
  • Stomata on lower surface to reduce water loss
  • Palisade and spongy layers to maximise light absorption
• Natural selection


  The process by which organisms with the best adaptations survive and reproduce, passing on their successful characteristics
• Natural selection


  1. Organisms show variation in characteristics

  2. Organisms with best adaptations survive and reproduce, weaker ones die out

  3. Genes from successful organisms passed to next generation

  4. Over time, best adaptations continue to be passed on, leading to new species
• Example of natural selection: Giraffes with longer necks could eat from trees, those with shorter necks died out, leading to all giraffes having long necks
• Punnet square


  Used to predict the inheritance of characteristics
• Extinction


  When all members of a species die out
• Causes of extinction


  • Changes to the environment
  • Destruction of habitat
  • New diseases
  • Introduction of new predators
  • Increased competition
• Biodiversity


  The variety of species within an ecosystem
• The more diverse a population is, the more likely they are to survive environmental changes
• Genetic modification


  The process of altering the genes of an organism
• Inheritance


  Characteristics passed from parents to offspring
• DNA


  The material which contains genetic information
• Chromosomes


  • Long strands of DNA which hold many genes, humans have 46 in the nucleus of cells
• Genes


  Sections of DNA which hold information for particular characteristics
• Alleles


  Two different genes which can code for the same characteristic, one inherited from each parent