Bio Gcse Aqa paper 1 triple higher

• Plant cell


  • Cell membrane - responsible for determining which bits going in and out of the cell
  • Cell wall - important for structure
  • Vacuole - important for structure
  • Cytoplasm - where most of the reactions take place
  • Ribosomes - responsible for protein synthesis
  • Chloroplasts - green bits
  • Mitochondria - pink ones, where energy is produced
  • Nucleus
• Animal cell


  • Cell membrane - controlling what goes in and out
  • Mitochondria - where energy is produced
  • Ribosomes - responsible for protein synthesis
  • Cytoplasm - where most of the reactions take place
  • Nucleus - where the DNA's hold, the control center of the cell
• There are several features of a plant cell that an animal cell doesn't share, for example, the cell wall, the vacuole, the chloroplasts.
• Bacterial cell


  • Cell membrane - controlling what goes in and out
  • Cytoplasm - where most of the reactions take place
  • Chromosome - DNA not in a nucleus
  • Flagella - used for locomotion
  • Ribosomes - for protein synthesis
  • Cell wall
• Differentiation


  When various different genes will be turned on and turned off, and that's when it will start to specialize
• Microscopy techniques


  • From the very, very basic starts where you had your lenses and you had to use the focus to see what was going on, to ones that you're probably more familiar with in school which have slightly more sophisticated lenses, to the massive ones that I used to work on, electron microscopes, where they're all controlled by computer
• Magnification


  Equals image height over object height
• DNA


  A long strand of deoxyribonucleic acid, made of lots of letters: As, Ts, Cs and Gs, which twist round into a double helix, and this double helix is still ridiculously long, so it further twists round so that it's in a chromosome, and this chromosome is located in the nucleus of a cell
• Mitosis


  1. DNA in the nucleus needs to condense into chromosomes

  2. Chromosomes line up down the middle

  3. Checks take place to make sure the chromosomes aren't gonna go astray

  4. Chromosomes are pulled apart to either end of the cell

  5. New nuclei will form

  6. Two identical daughter cells
• Stem cells


  Cells that have the potential to turn into any other type of cell
• Stem cells can be used to grow new brain cells, new bones, new organs or parts of organs
• To make stem cells, we take a nuclei out of an egg cell, we take nuclei from the patient's cell and insert that into the empty egg, the egg can then start to develop into an embryo, and from this embryo, the stem cells are then removed, and stem cells are turned into new cells
• This does come with quite a lot of controversy because human embryos are going to be created and then destroyed, and there were lots of religious objections to this, people just saying that life starts when embryos are created, and people who object to the destruction of embryos
• Diffusion


  The movement of gases or any particles that dissolved in solution moving down our concentration gradient from a high concentration to an area of low concentration
• Diffusion in the lungs

  • Carbon dioxide diffusing from the blood into lungs so they can be breathed out, and oxygen diffusing from the lungs into the blood so it can be taken around the body
• Diffusion in the gut

  • Digested food moving from the gut cavity into the blood so that it could be taken around the rest of the body
• Osmosis


  The movement of water through a partially-permeable membrane from the area of high water concentration to an area of low water concentration
• Active transport


  The movement across a membrane from a low concentration to a high concentration against the concentration gradient
• Tissue


  One type of cell carrying out one function
• Organ


  Made up from lots of different types of cells carrying out a joint function
• Organ system


  A group of organs that work together to carry out a function
• The hierarchy is cells, tissues, organs, organ systems
• Digestive system


  • Mouth - mechanically break down food
  • Salivary gland - produce amylase
  • Liver - produces bile
  • Gall bladder - stores bile
  • Small intestine - moves glucose, ions and other things into the blood
  • Stomach - churns out food, produces hydrochloric acid
  • Pancreas - produces enzymes
  • Large intestine - removes excess water
  • Rectum and anus - gets rid of waste food
• Lipase


  Breaks down fats into fatty acids and glycerol, made in the pancreas and small intestine, works in the small intestine
• Protease


  Breaks down proteins into amino acids, made in the stomach, pancreas and small intestine, works in the stomach and small intestine
• Amylase


  Breaks down starch into sugars, made in the salivary glands, pancreas and small intestine, works in the mouth and small intestine
• Enzyme mechanism


  Enzyme has a specifically-shaped active site, only one substrate or a couple of substrates are going to fit in there, they're gonna form an enzyme substrate complex, then the enzyme is either going to break apart things or it is going to join together things, it is then going to release the products, and then the enzyme is unchanged and can be used again
• Temperature affects enzyme activity

  At really low temperatures there is not enough energy, at the peak is the optimal temperature, after the peak the enzymes get denatured
• pH affects enzyme activity

  There is an optimal pH, when it is too high or too low, the bonds aren't going to be in place so the active site of the enzyme is going to be breaking down, so again, it is going to be denatured
• Respiratory system


  • Air goes in through the mouth or the nose down into the trachea, then into the bronchus, then into the bronchiole, and into the alveoli - where gas exchange happens
  • Diaphragm moves up and down to bring air in and out
  • Heart pumps blood around the body
  • Intercostal muscles allow the ribcage to expand
  • Ribs protect the lungs
• Cardiovascular system


  • Double system - blood gets pumped from the heart to the lungs, goes back to the heart and then gets pumped around the rest of the body
  • Right side - vena cava, right atrium, right ventricle, pulmonary artery
  • Left side - pulmonary vein, left atrium, left ventricle, aorta
  • Valves only allow blood to flow one way
  • Right side has a smaller muscle than the left side
• Veins carry deoxygenated blood apart from the pulmonary vein, arteries carry oxygenated blood apart from the pulmonary artery
• Pacemakers can be introduced to help the heart keep time, and tubes can be used to unblock blocked arteries
• Blood vessels


  • Arteries - thick walls, thin lumen, carry blood under high pressure
  • Capillaries - one cell thick, large surface area
  • Veins - thin walls, thick lumen, carry blood under low pressure, have valves
• Blood components


  • Serum - liquid component
  • Red blood cells - no nuclei, carry oxygen
  • White blood cells - part of immune system
  • Platelets - fragments of cells, important for clotting
• Cardiovascular disease


  Fatty deposits build up in coronary arteries, can lead to blood clots, restricts oxygen to cells, can lead to heart attack
• Risk factors for cardiovascular disease are smoking, high blood pressure, or having too much salts or fat in your diet
• Blood


  Liquid component of the blood, cells give it its actual color
• Red blood cells


  • Have no nuclei so they have more space to carry oxygen, which is their main function
• White blood cells


  Part of the immune system