Topic 2: Organisation

• Active site and Enzyme are COMPLEMENTARY
• Low temperature leads to low KE, so less COLLISIONS, therefore enzyme activity is lower.
• Cancerous cells divide uncontrollably
• Bile is alkaline, so if not present, the small intestine is acidic and enzymes are not at optimum pH for enzyme activity.
• Benedict's Test


  1. Benedict's solution is added to the food sample

  2. The sample is then heated

  3. The presence of reducing sugars is indicated by a color change from blue to orange-red
• Iodine Test

  1. Iodine solution is added to the food sample

  2. The presence of starch is indicated by a color change from brown to blue-black
• Biuret Test

  1. Biuret reagent is added to the food sample

  2. The presence of proteins is indicated by a color change from blue to violet or purple
• Emulsion Test

  1. The food sample is mixed with ethanol and shaken

  2. Water is then added

  3. A white emulsion forms if lipids are present
• Reducing Sugars

  Detected by Benedict's Test
• Starch

  Detected by Iodine Test
• Proteins

  Detected by Biuret Test
• Lipids/Fats

  Detected by Emulsion Test
• Improving validity of plant research: test roots / stems of plants (in the light and dark) • test other species of plant • measure the concentrations of glucose and starch • vary the time in the dark / light
• Factors to control in disease research: BMI, smoking habits, diet, previous drinking habits, medication, family history of liver disease • fitness levels, ethnicity, area of UK they live in
• Issues with surveys about alcohol consumptino (this can apply to any other topic):

  people underestimate / overestimate alcohol consumption

  • people may change (lifestyle / drinking) habits over time

  • some people may drink all their weekly alcohol at onc
• Effects of liver failure:

  No bile made

  Lactic acid not broken down

  Amino acids not deanimated

  No break-down of toxins

  Can't store glucagon
• Advantages of mechanical valves:

  • long lasting

  • do not need to go into hospital / surgery again

  • no ethical issues (surrounding use of living / animal tissue)

  • no risk of rejection

  • no need for anti-rejection / immunosuppressant drugs

  • no risk of transmission of disease
• Advantages of biological valves:

  no need to take anti-clotting medication
• mechanical valves • longer lasting or more durable or don’t wear out as easily or less likely to need replacing (within 6 years) • blood clots (on the brain) are more likely (after surgery) • patient has to take anti-clotting medication (for the rest of their lives)

  biological valves • no additional medication required • ethical issues surrounding use of animal tissue • valve may harden • more likely to need further operation or another new valve • more likely to be rejected • more likely to need (immuno-suppressant) medication

  both valves • both are readily available • little wait time
• Usage of Stem Cells:

  paralysis, diabetes, Parkinson’s, heart disease, stroke, cystic fibrosis, cancer, burns
• Usage of placebo and Double blind trial:

  to avoid the patients thinking they feel better with the drug/ psychological effect

  • as a control / comparison ignore to provide an independent variable • to avoid bias(ed results)
• Monoclonal antibodies


  Antibodies that have been designed to bind with a specific antigen
• Uses of monoclonal antibodies

  • Pregnancy test kits
  • Cancer diagnosis and treatment
  • Other diagnostic uses
• Pregnancy test kits using monoclonal antibodies

  1. Monoclonal antibodies are designed to bind with HCG hormone

  2. Monoclonal antibodies are attached to pregnancy test stick

  3. Woman urinates on test stick

  4. If pregnant, HCG binds to monoclonal antibodies

  5. Change in colour or pattern indicates pregnancy
• Monoclonal antibodies in pregnancy tests

  • They only bind with HCG
• Cancer diagnosis and treatment using monoclonal antibodies

  1. Cancerous cells have antigens

  2. Monoclonal antibodies are designed to bind with these antigens

  3. Monoclonal antibodies are injected into body

  4. They bind with cancer cells and clump them together

  5. This makes it easier to identify and treat the cancerous tumour
• Other diagnostic uses of monoclonal antibodies

  1. Monoclonal antibodies are used to identify and diagnose infections like HIV, AIDS, herpes, chlamydia

  2. Monoclonal antibodies have been attached to fluorescent dyes to make disease identification easier under UV light
• Production of monoclonal antibodies:

  An antigen is injected into a mouse

  The mouse naturally produces lymphocytes, which produce antibodies specific to the antigen

  Spleen cells which produce the lymphocytes are removed during a small operation

  The spleen cells are fused with human cancerous white blood cells called myeloma cells to form hybridoma cells which divide indefinitely

  These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original antigen
• Transpiration stream:

  (water is) transported in xylem

  water evaporates (from leaves)

  through the stomata
• Items in agar plate:

  • glucose / sugars / starch

  • amino acids / protein

  • hormones

  • ions / minerals

  • vitamins

  • water