organisation

• what is cell specialisation

  as an organism develops, cells differentiate and become specialised
• when do most types of animal cells differentiate?

  at an early stage of life
• when do many plant cells differentiate?

  they can differentiate throughout their life
• what happens to the cell as its differentiates?

  may change shape and sub-cellular structures develop to enable it to carry out a specific function
• what is a tissue?

  a group of cells that have a similar structure and function which all work together to do a job
• whats an example of a tissue?

  muscle tissue contracts to produce movement
• whats an organ?


  a different group of tissues gathered together to perform a particular fuction
• whats an organ example?

  the stomach has muscle tissue that contract to churn the contents
• whats an organ system?

  organs are organised into organ systems, which are groups of organs working together to perform a function
• whats an example of an organ system?


  digestive system
• what is an enzyme?

  biological catalysts, they speed up chemical reactions in living organisms
• what are the properties on an enzyme?

  properties

  1. all large proteins
  2. space within the proteien molecule called the active site
  3. all work best at a specific temp and pH (optimum)
• what is the enzyme lock and key theory?

  a model used to explain how enzymes work, the active site is the 'lock' and the substrate is the 'key'
• what is the active site?

  the area of the enzyme where the substrate molecule fit, where the chemical reaction occurs
• what happens if the temperature/ pH of an enzyme is too high or too low?

  it will denature, meaning the shape of the enzyme will change shape and no longer function
• how are digestive enzymes produced?

  by specialised cells in glands and in the gut lining
• whats the process of enzymes being produced?

  process:

  1. the enzymes pass out of the cells into the digestive system
  2. they come into contact with food molecules
  3. they catalyse the breakdown of large insoluble food molecules into smaller soluble molecules
• what are the 4 main digestive enzymes?

  amylase, protease, lipase
• what is a carbohydrase?

  an enzyme that can break down a carbohydrate e.g. amylase
• where is amylase produced? function of amylase?

  produced in salivary glands and pancreas, it breaks down starch into sugar (maltose)
• once starch is broken down into sugar what is it called?

  maltose
• where is protease produced? function of protease?

  produced in the stomach, pancreas and small intestine, it breaks down proteins into amino acids
• what does protease break proteins down into?

  amino acids
• where is lipase produced? function of lipase?

  produced in the pancreas and small intestine, it breaks down lipids into fatty acids and glycerol
• what does lipase break lipids down into?

  fatty acids and glycerol
• what is bile?

  a fluid, produced by the liver, that emulsifies fat
• how do we test for sugars, starch and protein? (required practical)

  using qualitative reagents to test for a range of carbohydrates, lipids and proteins
• method to test for sugars, starch and proteins?

  method:

  1. To test for sugars, add benedict's reagent and heat in a water bath for 2 mins, if sugar is present, it will turn red.
  2. To test for starch, add iodine solution. If starch is present, it will turn blue-black
  3. To test for protein, add biuret reagent. If protein is present, it will turn purple
• how do we investigate digestion? (required practical)

  investigating the effect of pH on the rate of reaction of amylase enzyme
• method for investigating digestion?

  method:

  1. put a test tube containing starch solution and a test tube containing amylase into a water bath at 37 degrees celcius
  2. after 5 mins, add amylase solution to the starch
  3. every 30 secs, take a drop from the mixture and test it for starch using iodine solution
  4. record how long it takes for the starch to be completely digested
  5. repeat the experiment at different pH values, using different buffer solutions
• whats the independent variable (one we change) of digestion RP?

  the pH
• whats the dependent variable (one we measure) of digestion RP?

  time taken for starch to be digested
• whats the control variable (one we keep the same) of digestion RP?

  temp, concentration and volume of starch and amylase
• what liquid is blood made of?

  plasma
• what 3 components are suspended in plasma?

  red blood cells, white blood cells, platelets
• what is haemoglobin?

  pigment in red blood cells that carries oxygen to the organs
• what do red blood cells do?

  • contain haemoglobin
  • do not contain a nucleus (more room for haemoglobin)
  • are very small, so they can fit through capillaries
  • shaped like biconcave disks, giving them a large surface area that oxygen can quickly diffuse across
• what do white blood cells do?

  • help to protect the body against infection
  • can change shape, so they can squeeze out of blood vessels into the tissues or to surround and engulf microorganisms (bacteria)
• what do platelets do?

  they are fragments of cells which collect at wounds and trigger blood clotting
• what does the heart do?

  pumps blood around the body in a double circulatory system