Organisation

• What are the levels of organisation in organisms, from least complex to most complex?

  Organelles ➔ cells ➔ tissues ➔ organs ➔ organ systems
• What are cells?


  Cells are the basic units of structure and function in living things
• What are tissues?


  Groups of cells that are similar in structure and function
• What are organs?


  Aggregations of tissues performing specific functions
• What are organs organised into

  Organs are organised into organ systems, which work together to form organisms.
• why is the digestive system an example of an organ system ?

  As several organs work together to digest and absorb food
• Give three reasons why we can't just make our cells even warmer to increase the rate of reactions?

  Heating our cells more would require a lot of energy

  Higher temperatures could damage our cells

  Higher temperatures would also speed up non-useful reactions
• What is a catalyst?


  A substance which increases the speed of a reaction, without being changed or used up in the reaction
• What are enzymes?


  An enzyme is a special type of catalyst that is made by a living organism. We sometimes call them biological catalysts.

  
  

  Enzymes are large proteins, so made from a long chain of amino acids.
• lock and key theory


  a substrate fits into its enzyme just like a key fits a lock
• What does optimum temperature mean?

  The temperature where the enzyme is the most active and works best at.
• Explain how increasing the temperature can cause an enzyme to denature.

  High temperatures start to break the bonds holding the enzyme together

  This causes the enzyme and it's active site to change shape

  This means the enzymes active site will no longer be complementary to the substrate

  the enzyme denatures

  ( same can apply to ph if to high or low )
• what are biological molecules?

  carbohydrates, proteins, and lipids.
• carbohydases break down carbohydrates into what ? also give an example of carbohydrate and what it breaks down ?

  simple sugars , amylase is an example of carbohydrate an breaks down starch.
• what is amylase site of production ?

  salivary gland

  panaceas

  small intestine
• What do digestive enzymes do?

  Convert food into small soluble molecules that can be absorbed into the bloodstream
• What do proteases break down?

  protease break down Proteins into amino acids
• where can proteases be found ?

  small intestine

  pancreases

  stomach - we call it pepsin in there
• What are lipids?


  fats and oils
• what is lipases broken down to ?

  breaks down lipids to glycerol and fatty acids
• Where are lipases produced?

  Pancreas and small intestine
• what are the products of digestion used for ?

  Build new carbohydrates, lipids and proteins. Glucose is used for respiration
• What is metabolism?


  sum of all chemical reactions in the body
• How does bile help with the digestion of lipids?

  It emulsifies the lipids aka fat which increases the surface area for lipase enzymes to break them down
• What is bile and where is it stored?

  bile is made in the liver but stored in the gall bladder then realsed into small intestine.

  It is alkaline to neutralise hydrochloric acid from the stomach

  also emulsifies fat to form small droplets which increase surface area

  these alkaline conditions and large surface area make rate of digestion by lipase faster.
• The digestive system has two main roles. Briefly describe each of them.


  Digestion - process of breaking down large food molecules into smaller molecules

  Absorption - process of absorbing these small food molecules into the body
• What do the salivary glands do?

  the salivary glands in our mouth release saliva which lubricates the food and makes it easier to swallow.

  
  

  It also contains the enzyme amylase, which breaks down starch into maltose.
• 3 roles of the stomach

  The stomach contracts its muscular walls to churn and mix the food.

  It produces pepsin, which is a type of protease enzyme, and breaks proteins down into amino acids.

  It produces hydrochloric acid, which a) provides the right pH for pepsin to function, and b) kills microorganisms aka bacteria
• What is the main role of the large intestine?


  Reabsorbs excess water and stores and eliminates undigested food into rectum
• What is the order of the digestive system?

  mouth ( salivary gland), esophagus (gullet), stomach, small intestine ( get things from gall ballder pancreases and liver) then takes digestive food to blood stream , large intestine, rectum, anus
• investigating effect of pH on enzyme activity

  1) Put a drop of iodine solution into every well of the spotting tile.

  2) Place a Bunsen burner on a heat-proof mat and a tripod and gauze over until it is 35C use a warm bath to keep temp constant

  3) Use a syringe to the 1cm3 of amylase solution and 1cm3 of a buffer solution with a pH of 5 to a boiling tube.

  4) Next, use a different syringe to add 5cm3 of a starch solution to the boiling tube

  5) Immediately mix the contents of the boiling tube and start a stop clock

  6) Use continuous sampling to record how long it takes for the amylase

  7) When the iodine solution goes brown/orange, starch is no longer present.
• how to calculate rate of reaction


  Amount of reactant used or product formed / time

  
  

  or 1000/time
• What is Bendict's test used for ?

  reducing sugars eg biscuits, cereal and bread
• what is the iodine test used for ?

  starch eg pasta rice and potato
• what is the buriet test used for ?

  proteins such as meat and cheese
• What is the Sudan III test for ?

  test for lipids like olive oil milk and margarine
• how do you do Sudan III test for lipids

  Place 5cm3 of your food sample in a test tube.

  Add 3 drops of Sudan III stain solution.

  Gently shake.

  If a red layer separates out on top, then lipid was present.
• how do you do benedict's test for reducing sugars


  - place food sample in 5cm2 test tube

  - add Benedict solution of 10 drops to test tube

  - then place in water bath of 75* using test holder and face away from you

  - if present it will go from blue -- green yellow or brick red depending on sugar concentration if not stay blue
• how do you do an iodine test for starch ?

  - add drops iodine solution to food sample of 5cm2

  - shake if present change from browny organe - black or blue black
• How do you do an buriet test for proteins

  - add 2cm2 or buriet solution to 2cm2 of food sample

  - shake gently if present will change from blue - purple