B2

• tissue


  a group of cells with a similar structure and function
• organ systems 


  organs which work together
• mouth

  enzymes in the saliva begin to digest the starch into smaller sugar molecules
• stomach

  enzymes begin to digest proteins

  hydrochloric acid helps digest

  churning action turns food to fluid which increases surface area for enzymes to digest
• the products of digestion are used by the body to build new carbohydrates, proteins and lipids
• enzymes catalyse chemical reactions
• active site is the part of the enzyme that binds to the substrate and is the part of the enzyme that catalyses the reaction
• proteins are broken down by enzymes called proteases, found in the stomach, pancreas and small intestine

  • long chains of amino acids
• • starch is a chain of glucose molecules
  • broken down by carbohydrase
  • found in saliva and pancreatic fluid
• active site denatures if conditions are too acidic or too alkaline
• small intestine


  5m long

  very large surface area

  covered in villi which helps absorb molecules

  villi have a membrane to help with easy diffusion
• the left side of the heart is thicker then the right side as it pumps blood all over the body
• 1. deoxygenated blood is pumped from the heart to the lungs where it is oxygenated
  2. the oxygenated blood returns to the heart and is pumped around the whole body
  3. blood goes from the organs back to the heart deoxygenated
• capillaries have thin walls for quick diffusion
• blood plasma

  transports substances
• red blood cells

  transport oxygen from lungs too body cells

  contains haemoglobin

  no nucleus

  biconcave disc means wider surface area so faster diffusion
• white blood cells

  antibodies for immune system

  nucleus which contains DNA which gives the cell its job
• cardiovascular diseases are in the heart and blood
• coronary heart disease

  fat builds up in the arteries which prevents blood and oxygen flow to the heart

  statins and stents can be used to help
• • statins reduce blood cholesterol through a daily pill
  • side effects of liver problems
• • stents are tubes which are inserted into the coronary arteries to keep them open
  • does not treat underlying causes
• meristem tissue


  contains stem cells which can differentiate into different plant tissues
• transpiration is where water evaporates from the surface of the leaves
• transpiration rate is greater when it is hotter and dryer as there is faster evaporation

  transpiration is greater in high light intensity
• stomata is surrounded by guard cells which swell to let water in and shrink to let water out
• Benign tumor


  Growth of abnormal cells which are found in one area, contained within a membrane, do not invade or spread to other parts of the body
• Risk factors for developing cancer

  • Genetic (e.g. certain types of breast cancer, prostate cancer, cancer of the large intestine)
  • Lifestyle (e.g. lung cancer linked to smoking, skin cancer linked to UV exposure, mouth and throat cancer linked to alcohol)
  • Environmental (e.g. radon, a radioactive gas that increases risk of lung cancer)
• Radon releases ionizing radiation that damages DNA in cells, causing uncontrolled cell division leading to cancer