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 - control center of the cell
• 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 - on the outside
• Specialized cells


  • Neuron - looks very different to a muscle cell, which is going to look very different to a skin cell or very different to a set of cells in the gut
  • They specialize to do their jobs
• Cell differentiation


  1. Cells start off looking the same

  2. Various different genes will be turned on and turned off

  3. This is when it will start to specialize
• Microscopy techniques


  From the very basic starts where you had your lenses and you had to use the focus to see what was going on, to the massive ones that I used to work on, electron microscopes, where they're all controlled by computer
• Magnification


  Magnification equals image height over object height
• DNA


  • A long strand of deoxyribonucleic acid, made of lots of letters: As, Ts, Cs and Gs
  • Twists round into a double helix
  • Further twists round so that it's in a chromosome
  • 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


  • Have the potential to turn into any other type of cell
  • Used to grow new brain cells for Parkinson's disease
  • Used to grow new bones to fill the gap for brain or spinal injury, bone injuries
  • Used to grow new organs or parts of organs instead of waiting and making someone wait on the incredibly long transfer waiting list
• 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. 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


  • Movement of things from a high concentration down the diffusion gradient to an area of low concentration
  • Could be things moving from an area inside a cell where they've been made to another area, or it could be things moving out of a cell
  • Happens in the lungs, the alveoli, the air spaces
  • Happens in the gut, the villi of the gut
• Osmosis


  Specifically 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


  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
• Hierarchy


  • Cells
  • Tissues
  • Organs
  • Organ systems
• Digestive system


  • Mouth - mechanically break down food
  • Salivary gland - produces amylase
  • Liver - produces bile
  • Gall bladder - stores bile
  • Small intestine - moves glucose, ions and other things into the blood and has a very large surface area
  • Stomach - churns out food, provides an environment for proteases to work
  • Pancreas - produces enzymes
  • Large intestine - removes excess water
  • Rectum and anus - gets rid of waste food
• Digestive enzymes


  • 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 activity


  • Temperature - lopsided curve, optimal temperature, denatured above optimal
  • pH - symmetrical curve, optimal pH, denatured above and below optimal
• Respiratory system


  • Air goes in through the mouth or the nose down into the trachea, into the bronchus, into the bronchiole, 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 left side
• The majority of the time, veins carry deoxygenated blood apart from the pulmonary vein which carries oxygenated blood back into the heart. And the majority of the time, arteries carry oxygenated blood apart from the pulmonary vein which carries deoxygenated blood from the heart to the lungs.
• Blood vessels


  • Arteries - thick walls, thin lumen, carry blood under high pressure
  • Capillaries - one cell thick, allow for diffusion, in a mesh network
  • Veins - thin walls, thick lumen, carry blood under low pressure, have valves
• Blood components


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


  • Fatty deposits build up in the coronary arteries
  • Can lead to the formation of blood clots
  • Blood clot can block an artery
  • Restricts oxygen to some cells
  • Cells die
  • If too many cells die, can lead to a heart attack
• Risk factors for cardiovascular disease are smoking, high blood pressure, or having too much salts or fat in your diet.
• 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
• Cardiovascular disease


  Fatty deposits build up in coronary arteries around the heart, can lead to blood clots
• Blood clot blocking an artery

  Restricts oxygen to cells, causing them to die
• Many cells dying


  Can lead to heart attack if heart can't function properly or pump blood
• Risk factors for cardiovascular disease

  • Smoking
  • High blood pressure
  • Too much salt or fat in diet
• Health


  Overall state of physical and mental wellbeing, affected by diet, exercise, community, loneliness, friends, and genes
• Cancer


  Cells begin to divide uncontrollably, leading to lumps (benign or malignant tumors)
• Risk factors for cancer

  • Smoking
  • Poor diet
  • Sun exposure
  • Unprotected sex