Biology

• Red blood cell


  Transport oxygen around the body
• Red blood cell


  • No nucleus so more room to carry oxygen
  • Contains a red pigment called haemoglobin that binds to oxygen molecules
  • Flat bi-concave disc shape to increase surface area-to-volume ratio
• Root hair cell


  Absorb mineral ions and water from the soil
• Root hair cell


  • Long projection speeds up the absorption of water and mineral ions by increasing the surface area of the cell
  • Lots of mitochondria to release energy for the active transport of mineral ions from the soil
• Palisade cell


  Enable photosynthesis in the leaf
• Palisade cell


  • Lots of chloroplasts containing chlorophyll to absorb light energy
  • Located at the top surface of the leaf where it can absorb the most light energy
• Key terms


  • cell membrane
  • cell wall
  • chloroplast
  • chromosome
  • concentration
  • cytoplasm
  • dilute
  • DNA
  • eukaryotic
  • gill filaments
  • gradient
  • magnification
  • mitochondria
  • nucleus
  • partially permeable membrane
  • passive process
  • permanent vacuole
  • plasmid
  • prokaryotic
  • resolution
  • ribosome
  • root hair cell
  • stomata
• Enzymes


  Large proteins that catalyse (speed up) reactions. Enzymes are not changed in the reactions they catalyse.
• Heart


  Organ that pumps blood around the body
• Lock and key theory

  1. The enzyme's active site (where the reaction occurs) is a specific shape.

  2. The enzyme (the lock) will only catalyse a specific reaction because the substrate (the key) fits into its active site.

  3. At the active site, enzymes can break molecules down into smaller ones or bind small molecules together to form larger ones.

  4. When the products have been released, the enzyme's active site can accept another substrate molecule.
• Heart


  • Made from cardiac muscle tissue
  • Supplied with oxygen by the coronary artery
• Heart rate


  Controlled by a group of cells in the right atrium that generate electrical impulses, acting as a pacemaker
• Artificial pacemakers


  Used to control irregular heartbeats
• Parts of the digestive system

  • Mouth
  • Salivary glands
  • Oesophagus
  • Stomach
  • Liver
  • Gall bladder
  • Pancreas
  • Small intestine
  • Large intestine
  • Rectum
  • Anus
• Salivary glands


  Make saliva containing the enzyme amylase
• Artery


  • Carries blood away from the heart (high pressure)
  • Thick, muscular, and elastic walls
  • The walls can stretch and withstand high pressure
  • Small lumen
• Stomach


  Churns food, releases protease to digest proteins, releases hydrochloric acid to kill pathogens
• Vein

  • Carries blood to the heart (low pressure)
  • Have valves to stop blood flowing the wrong way
  • Thin walls
  • Large lumen
• Liver


  Makes bile
• Capillary


  • 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
• Gall bladder


  Stores bile, which is alkaline to neutralise hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area
• Double circulatory system


  • Blood passes through the heart twice for every circuit around the body
  • Right ventricle pumps blood to the lungs where gas exchange takes place
  • Left ventricle pumps blood around the rest of the body
• Components of blood

  • Red blood cells
  • Plasma
  • Platelets
  • White blood cells
• Red blood cells


  Bind to oxygen and transport it around the body
• Plasma


  Transports substances and blood cells around the body
• Platelets


  Form blood clots to create barriers to infections
• White blood cells


  Part of the immune system to defend the body against pathogens
• Pancreas


  Makes enzymes: amylase, lipase, and protease
• Small intestine


  Where digested food is absorbed into the blood
• Large intestine


  Where water and minerals are absorbed into the blood
• Rectum


  Stores faeces
• Anus


  Expels faeces
• Digestive enzymes


  • Amylase
  • Proteases
  • Lipases
• Breathing in


  1. Air moves into the body through the mouth and nose

  2. Down the trachea

  3. Into the bronchi

  4. Through the bronchioles

  5. Into the alveoli (air sacs)
• Amylase


  Breaks down starch into glucose
• Oxygen then diffuses into the blood in the network of capillaries over the surface of the alveoli
• Transpiration


  Movement of water from the roots to the leaves through the xylem
• Proteases


  Break down proteins into amino acids
• Lipases


  Break down lipids into fatty acids and glycerol
• Viruses


  Live and reproduce rapidly inside an organism's cells, can damage or destroy the cells