Organisation

• Food Tests (Required Practical)

  1. Add 2cm3 of starch solution into the test tube

  2. Extract some of the amylase/starch solution after 10 seconds and place one drop into the first well of the spotting tile

  3. Continue to place one drop into the next well of the spotting tile, every 10 seconds, until the iodine remains orange

  4. Record the time taken for the starch to be completely digested by the amylase by counting the wells that were tested positive for starch

  5. Repeat steps for pH values 7 and 10
• Effect of pH on the Rate of Reaction of Amylase (Required Practical)

  1. Use the marker pen to label a test tube with the first value of pH buffer solution (pH 4) and stand it in the test tube rack

  2. Into each well of the spotting tiles, place a drop of iodine

  3. Measure 2cm3 of amylase and pour into the test tube

  4. Measure 1cm3 of the buffer solution and pour into the test tube

  5. Leave this to stand for five minutes and then use the thermometer to measure the temperature
• Independent variable


  pH of the buffer solution
• Dependent variable


  Time taken for the reaction to complete (how long it takes for all the starch to be digested by the amylase)
• Iodine is used to test for the presence of starch. If starch is present, the colour will change to blue-black.
• The purpose of the digestive system is to break down large molecules into smaller, soluble molecules, which are then absorbed into the bloodstream. The rate of these reactions is increased by enzymes.
• Enzyme


  A biological catalyst that speeds up chemical reactions without being changed or used up
• Enzymes


  • They lower the activation energy required for the reaction to occur
  • They are made up of chains of amino acids folded into a globular shape
  • They have an active site which the substrate (reactants) fits into
  • They are very specific and will only catalyse one specific reaction
  • They work optimally at specific conditions of pH and temperature
• In extremes of pH or temperature, the enzyme will denature, meaning the bonds holding together the 3D shape of the active site will break and the active shape will deform, so the substrate will not be able to fit into the active site anymore and the enzyme cannot function.
• Pulmonary circulation


  Serves the lungs and brings deoxygenated blood to exchange waste carbon dioxide gas for oxygen at the alveoli
• Systemic circulation


  Serves the rest of the body and transports oxygen and nutrients from digestion to the cells of the body, whilst carrying carbon dioxide and other waste away from the cells
• The systemic circulation flows through the whole body, so the blood is flowing at a much higher pressure than in the pulmonary circuit.
• Bile is produced in the liver and stored in the gall bladder. It is an alkaline substance which neutralises the hydrochloric acid in the stomach. It also works to emulsify fats into small droplets, increasing the rate of their digestion by lipase.
• Enzymes and their substrates

  • amylase - starch
  • protease - protein
  • lipase - lipid
• Sino-atrial node (SAN)


  Located near the right atrium and it stimulates the atria to contract
• Atrio-ventricular node (AVN)


  Located in between the ventricles and stimulates them to contract
• Artificial pacemakers can be surgically implanted into a person if their heart nodes are not functioning correctly.
• Coronary heart disease is a condition resulting from blockages in the coronary arteries, the main arteries which supply blood to the heart itself. These blockages are caused by a build-up of fatty deposits.
• Lifestyle factors that increase the risk of coronary heart disease

  • Diet high in saturated fat
  • Smoking
  • Stress
• Red blood cells


  Transport oxygen attached to the haem group in their structure. They have a biconcave shape to increase surface area and do not contain a nucleus so they can bind with more oxygen molecules.

  
• White blood cells


  Form part of the immune system and ingest pathogens and produce antibodies
• Platelets


  Important blood clotting factors
• Cancer is the result of uncontrolled cell growth and division, and the uncontrolled growth of cells is called a tumour.
• Leaves


  Plant organs whose main function is to absorb sunlight energy for use in photosynthesis. They contain chloroplasts with chlorophyll which absorb the sunlight.
• Photosynthesis


  carbon dioxide + water -> oxygen + glucose
• Leaves


  • Typically flat and thin with a large surface area to maximise absorption of sunlight and carbon dioxide
  • Thin shape reduces the distance for diffusion of gases
• Blood flow


  1. Heart pumps blood more forcefully out

  2. Blood only flows in one direction

  3. Valves in heart close under pressure to prevent backward flow
• Cancer


  Uncontrolled cell growth and division
• Tumour


  Uncontrolled growth of cells
• Leaves


  • Flat and thin with large surface area
  • Contain xylem and phloem vessels
  • Have air spaces in spongy mesophyll layer for gas diffusion
  • Have guard cells to control stomata
• Photosynthesis


  Process where sunlight energy is used to convert carbon dioxide and water into oxygen and glucose
• Root hair cells


  • Finger-like projections to increase surface area
  • Narrow shape to fit in soil spaces
  • Many mitochondria for active transport
• Xylem


  • Made of dead, lignified cells joined end-to-end
  • Transport water and dissolved minerals in transpiration stream
  • Provide structural support
• Phloem


  • Made of living cells with small holes between them
  • Transport dissolved sugars and glucose around the plant
• Transpiration


  1. Loss of water by evaporation and diffusion from leaves

  2. Creates transpiration stream drawing more water up
• Environmental factors


  Affect rate of transpiration
• Health


  State of being free from illness or disease, referring to physical and mental wellbeing
• Lifestyle factors


  Can impact health
• Having one illness


  Can increase risk of another illness
• Smoking


  Increases risk of lung cancer