Biology: Topic 2 - Organisation

• Levels of organisation. least complex to most complex

  Organelles -> cells -> tissues -> organs -> organ systems
• What are enzymes?


  Catalysts produced by living things
• Explain the lock and key theory

  that the enzyme's active site and the shape of the substrate molecule are complementary to one another. This allows the substrate to fit into the enzyme, like how a key would fit into a lock. If the substrate doesn't fit, then the enzyme will not act on it
• Explain why enzymes have an optimum pH of 7

  if the pH is too high or low it can interfere with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme
• Investigating the 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

  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 to break down all starch

  7) When the iodine solution goes brown/orange, starch is no longer present.

  8) repeat experiment with buffer solutions of different pH values to see how it affects time take for starch to be broken down
• what are the sites of amylase production

  - salivary glands

  - pancreas

  - small intestine
• what are the sites of protease production?

  - stomach (it's called pepsin there)

  - pancreas

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

  To build new carbohydrates, lipids and proteins. Some glucose is used in respiration
• what is bile

  Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
• what does the salivary glands do?


  releases saliva which lubricates food making it easier to swallow

  produces amylase enzyme

  
• What does the liver do?

  produces bile which neutralises stomach acid and emulsifies fats.

  
• what does the gall bladder do?

  It stores bile before it's released into the small intestine

  
• Food tests - Iodine solution test for starch

  1. make a food sample, transfer 5cm3 to test tube

  2.add a few drops of iodine solution and gently desk the boiling tube

  3. if starch is present the solution will change from browny orange to black, or if starch isn't present it will change to red

  
• Food tests - Biuret test for proteins

  1) Prepare food sample and transfer 2cm3 of it to a test tube

  2) add 2cm3 of biuret solution to sample and mix contents by gently shaking it

  3) if food sample contains protein solution will change from to blue to purple.

  if not it will remain blue

  
• Food tests - Sudan III test for Lipids


  1) prepare food sample (no need to filter) and transfer 5cm3 into test tube

  2) use a pipette to add 3 drops of solution to test tube and gently shake it

  3) If lipids are present the mixture will separate into two layers and top layer will be red .

  
• How the lungs are adapted for gaseous exchange

  Large surface area - many alveoli are present in the lungs with a shape that further increases surface area.

  Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance.

  Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface.
• How does the alveoli carry out gas exchange in the body

  1) alveoli in our lungs are tiny air sacs. They are surrounded by capillaries - where gas exchange occurs

  2) Oxygen diffuses out of alveolus into the blood. Carbon dioxide diffuses out of the blood into the alveolus to be breathed out.

  3) When blood reaches body cells oxygen is released from the red blood cells and diffuses into the body cells.

  4) at the same time, carbon dioxide diffuses into the blood . Then carried back into the lungs

  
• what is the heart?

  an organ that pumps blood around the body in a double circulatory system.

  
• What stops blood from flowing backwards

  valves

  
• what are the four chambers of the heart?

  right atrium, right ventricle, left atrium, left ventricle

  
• How does the heart pump blood around the body?

  1) Blood flows into the two atria from the vena cava and the pulmonary vein.

  2) The atria contract, pushing the blood into the ventricles.

  3) The ventricles contract, forcing the blood into the pulmonary artery and the aorta, and out of the heart.

  4) The blood then flows to the organs through arteries, and returns through veins.

  5) The atria fill again and the whole cycle starts over.
• what is the function of the coronary arteries?

  They supply oxygenated blood to the heart itself
• What is the pacemaker of the heart?

  a group of cells in the right atrium that produce small electric impulse which spreads to surrounding muscle cells causing them to contract.
• Why is an artificial pacemaker used?

  To control heartbeat if the natural pacemaker cells don't work properly e.g irregular heartbeat
• what are three different types of blood vessels

  arteries - these carry the blood AWAY from the heart

  capillaries - these are involved on the exchange of materials at . the tissue

  veins - these carry blood TO the heart
• structure of arteries


  - strong and elastic walls as the heart pumps blood out at HIGH PRESSURE

  - thick walls/ layer of muscle to make them strong and elastic fibres to allow them to stretch and spring back

  
• structure of capillaries


  - permeable walls, so substances an diffuse in and out

  - really tiny - to small to see

  - supply food and oxygen, and take away waste like CO2

  - thin walls to increase the rate of diffusion by decreasing the distance over which it occurs.

  
• Structure of veins


  - thinner walls than arteries a blood is at a lower pressure

  - bigger lumen than arteries to help blood flow

  - have valves to make sure blood flows in right direction

  
• Function of white blood cells

  - defends against infection

  - some change shape to ingest bacteria (phagocytosis)

  - others produce antibodies to fight microorganisms as well as antitoxins to neutralise any toxins produced by microorganisms

  
• function of platelets

  - help blood clot

  - small fragment of cell (no nucleus)

  - help blood to clot at a wound to stop blood from pouring out and o stop microorganisms getting in

  - lack of platelets can cause excessive bleeding and bruising

  
• What is coronary heart disease? (Cardiovascular diseases)

  is when the coronary arteries that supply the blood to the muscle of the heart get blocked by layer of fatty materials building up.
• What are statins?


  Drugs that can reduce the amount of 'bad' cholesterol present in the bloodstream. This slows down the rate of fatty deposits forming.
• What is cholesterol?

  a lipid that your body produces and needs to function properly.

  Having too much of LDL (bad) cholesterol in the bood stream can cause fatty deposits to form in the arteries.
• What are artificial hearts and what are they used for?

  they are mechanical devices that pump blood for a person whose own heart has failed. They are used temporary to keep a person alive until a donor heart can be found.
• advantages and disadvantages of artificial hearts

  ADVANTAGES

  - less likely to be rejected by body's immune system because they are made from metals or plastics so the body doesn't recognise them as 'foreign' and attack in the same way as it does with living tissues

  DISADVANTAGES

  - surgery can lead to bleeding and infection

  - don't work as well as healthy natural ones (parts of the heart could wear out or electrical motor could fail.

  - blood doesn't flow through artificial hearts as smoothly which blood clots and lead to strokes.
• advantages and disadvantages of mechanical valves.

  ADVANTAGES:

  - they can last a lifetime unlike biological valves

  - provide better blood flow and may not need to be replaced as often.

  DISADVANTAGES:

  - requires life-long use of blood-thinning medication to prevent blood clots (people may forget)

  - they can also produce a clicking sound which may bother some.
• Artificial blood


  in emergencies, when someones lost lots of blood, artificial blood eg salt solution/saline can restore the volume of the blood safely for a while.
• advantages and disadvantages of artificial blood

  ADVANTAGES

  - can be stored for longer periods of time

  - it doesn't carry the risk of transmitting diseases that donated blood may have

  DISADVANTAGES:

  - it is still being developed and may not be as effective as real blood in terms of oxygen-carrying capacity

  - expensive to produce and may not be readily available in all medical settings
• What is health?

  the state of physical and mental well-being.
• What are communicable diseases?

  Diseases that can be spread from person to person or between animals and people. They can be caused by pathogens and can be described as contagious or infectious. Examples include measles and malaria