Biology

• enzymes are biological catalysts produced by living things which increase the speed of a reaction without being used up
• • active site fits the complimentary substrate perfectly
  • active site and substrate attach
  • breaks down substrate into products
• digestion is the breakdown of large insoluble food into small soluble molecules
• enzyme- lipase

  substrate- lipid

  products- fatty acids and glycerol produced- pancreas, small intestine
• liver produced bile (produced in liver and stored in the gallbladder) which emulsifies fat into smaller drops to increase surface area and speed up the rate of reaction
• enzyme- amylase

  substrate- starch

  products- sugars (glucose, maltose, dextrins) produced- mouth, small intestine, pancreas
• enzyme- protease

  substrate- protein

  products- amino acids

  produced- stomach (PH2, called pepsin), small intestine, pancreas
• blood components

  -blood plasma (carries dissolves food, hormones, urea and waste CO2)

  -platelets (no nuclear, clots blood, fragments of cells)

  -white blood cells (nuclear, help our immune system to produce antibodies and engulf pathogens)

  -red blood cells (carry oxygen in haemoglobin, thin membrane to diffuse gas easier, biconcave shape to increase surface area, able to press up walls, flexible, no nucleus to make room for oxygen)
• ARTERIES

  • thick walls (maintain pressure and push blood)
  • small lumen (blood stays under high pressure)
  • thick elastic tissue (stretch under pressure and spring back)
  • no valves
  • function = transport and distribute oxygenated blood to tissues away from the heart
• VEINS

  • thin muscle and elastic fibre
  • large lumen (less pressure)
  • general body muscles contract and move blood along
  • contains valves (blood flows against gravity and under low pressure)
  • function = collects deoxygenated blood and returns to the heart
• CAPILLARIES

  • smallest vessel
  • narrow lumen (but not under high pressure, blood moves from pressure from arterioles)
  • small pores
  • ones cell thick permeable walls (more efficient gas exchange)
  • no valves
  • function = exchange of substances (O2 and CO2) and links veins and arteries
• what do you use to test for reducing sugars?

  benedict’s solution
• testing for sugars (benedict’s)

  negative result = blue

  positive result = green, yellow, brick red
• what do you use to test for starch?

  iodine
• testing for starch (iodine)

  negative result = browny-orange

  positive result = blue-black or black
• what do you use to test for proteins?

  biuret solution
• testing for protein (biuret)

  negative = blue

  positive = purple / lilac or pink
• what do you use when testing for lipids?

  sudan III stain solution or ethenol
• testing for lipids (sudan III stain solution or ethenol)

  SIISS -

  negative = no change

  positive = mixture will separate, red layer will form

  ethanol -

  negative = no change

  positive = white emulsion
• define active transport 


  the movement of molecules or ions from a low to a high concentration (against concentration gradient) across a partially permeable membrane
• ACTOVE TRANSPORT

  • molecule arrived at carrier protein
  • combines with carrier protein
  • energy supplied to carrier protein
  • energy used by carrier protein to change shape (from mitochondria)
  • molecule is carried and released other side of the membrane
  • carrier protein returns to original shape
• where does active transport take place?

  -root cells

  -villi
• define diffusion

  the movement of particles from a high to a low concentration
• FACTORS EFFECTING DIFFUSION

  • temperature (increase in temperature, increase in kinetic energy, particles move at a quicker rate)
  • surface area (more particles exposed to react)
  • concentration gradient (higher concentration gradient , faster diffusion, particles increase in kinetic energy)
• ALVEOLI ADAPTATIONS

  • thin membrane
  • large surface area
  • moist
  • rick blood supply
• how do the alveoli work? gas exchange

  Air containing a high concentration of oxygen enters the alveoli upon inhalation. Capillarys surrounding have a low concentration of oxygen. Oxygen diffuses from a high to a low concentration in the blood. Also, the blood contains a high concentration of CO2, so it diffuses to a low concentration in the alveoli
• define osmosis

  movement of water from a dilute to a concentrated solution across a partially permeable membrane
• hypotonic solution


  solution is more dilute than potato
• isotonic solution 


  solution is the same concentration as potato
• hypertonic solution 


  solution is more concentrated than potato
• What happens when an enzyme is not at its optimum?

  denatures
• what happens when an enzyme denatures?

  the active site changes shape and can no longer fit its complementary substrate
• what is an optimum for an enzyme?

  the temperature or PH where an enzyme works best
• what is the optimum PH for pepsin/protease?

  2
• what is the optimum temperature and PH for amylase?

  PH- 7

  temperature- 37 °c
• denatured enzymes

  • irreversible
  • wrong PH (too acidic or alkali)
  • too cold= not denatured but reaction is slow
  • too hot= denatured
• Metabolism is the total sum of chemical reactions in an organism in which molecules are made or broken down
• respiration is the process of oxidising glucose to release energy
• where does respiration happen?

  every cell
• what is energy used for?

  • movement
  • contraction of muscles
  • repairing and replacing muscles
  • regulate temperature