b3 and b4

• amylase is produced in salivary glands, pancreas, small intestine.
• Protease is produced in stomach , pancreas , small intestine
• Lipase is produced in pancreas and small intestine
• Enzymes are large proteins that catalyse reactions
• Lock and key theory

  Enzymes active site is a specific shape

  The enzyme will only catalyse a specific reaction because the substrate fits into its active site

  At active site , enzymes can break molecules down into smaller ones

  When products are released, the enzymes active site can accept another substrate molecuke
• Large intestine - water and minerals are absorbed into blood
• Rectum stores faeces , anus expels faeces
• Stomach - churns food , releases protease - digests proteins , release hydrochloric acid
• Oesophagus - carries food to stomach
• salivary glands - make saliva containing amylase
• small intestine - digested food is absorbed into blood
• gall bladder - stores bile - neutralises hydrochloric acid from stomach and emulsifies fat to form droplets with large surface area
• as the temperature increases,

  the rate of reaction increases

  because enzyme and

  substrate molecules move

  around faster and collide

  more frequently
• the human circulatory system is described as a double circulatory system:

  Right ventricle pumps blood to lungs where gas exchange take place

  Left ventricle pumps blood around rest of body
• aorta - carries oxygenated

  blood around the body
• pulmonary vein - brings oxygenated

  blood from the

  lungs
• vena cava - brings

  deoxygenated

  blood into the

  heart
• pulmonary artery - takes deoxygenated

  blood to the lungs
• Coronary heart disease is caused by a build up of fatty material in the coronary arteries, making them narrow, and reducing blood flow. Stents can be used to help keep the coronary arteries open.
• When breathing in, air moves into the body through the mouth and nose

  then down the trachea then into the bronchi then through the bronchioles then lastly into the alveoli (air sacs).
• arteries - carries blood away from the heart. they are thick , muscular and have elastic walls. It can stretch and stand high pressure they have small lumen.
• veins - carries blood to the heart at low pressure. They have valves to stop flowing the wrong way, thin walls and large lumen
• capillaries - carries blood to tissues and cells connects arteries and veins. one cell thick – short diffusion distance for substances to move

  between the blood and tissues

  • very narrow lumen
• Palisade mesophyll - tightly packed cells, lots of chloroplast - absorb light for photosynthesis
• Spongy mesophyll - spherical cells. lots of air spaces to allow gases to diffuse quickly. Large surface area to increase gas exchange
• Guard cell - tiny openings on lower surface of the leaf that allow gases to move into and out of leaf.
• Translocation - movement of dissolved sugars from leaves to rest of plant through phloem
• Transpiration- movement of water from roots to leaves in xylem. Water is lost through stomata by evaporation