Biology paper 1

• 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
• There isn't really a typical type of cell because there are a wide range of differentiated specialized cells.
• Differentiation


  When various different genes will be turned on and turned off, and that's when it will start to specialize
• 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, salivary gland, liver, gall bladder, small intestine, stomach, pancreas, large intestine, rectum and anus
• 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 optimal temperature the enzyme activity is highest, after the optimal temperature 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, the diaphragm moves up and down to bring air in and out, the heart pumps blood around the body, the intercostal muscles allow the ribcage to expand, and the 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 and left sides of the heart, vena cava, atrium, ventricle, artery, vein, aorta, valves, thicker muscle on 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 arteries in cardiovascular disease
• Blood vessels


  • Arteries have thick walls and thin lumen, capillaries are one cell thick, veins have thin walls and thick lumen
• Blood components


  Serum - liquid component, red blood cells - no nuclei, white blood cells - part of immune system, platelets - for clotting
• Cardiovascular disease


  Fatty deposits build up in coronary arteries, can lead to blood clots blocking arteries, restricting oxygen to cells, causing cell death, leading to heart attack, risk factors are smoking, high blood pressure, too much salt or fat in diet
• Blood


  Liquid component of the blood, with cells giving 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
• Platelets


  Fragments of cells, important for clotting