PAPER 2

• Photosynthesis is going to take water, carbon dioxide, and turn it into oxygen and glucose
• Light


  Not a reactant in photosynthesis, but a condition that's needed
• Photosynthesis formula


  Water (H2O) + Carbon dioxide (CO2) → Oxygen (O2) + Glucose (C6H12O6)
• The photosynthesis formula needs to be balanced, with the numbers in the right place
• Endothermic reaction


  Photosynthesis takes in energy
• Requirements for photosynthesis


  • Chlorophyll
  • Water
  • Carbon dioxide
  • Sunlight
• Percentage level of carbon dioxide increases

  Rate of photosynthesis increases (up to a point)
• Temperature increases


  Rate of photosynthesis increases (up to an optimal point)
• Enzymes in photosynthesis


  They are denatured, not killed, when it gets too hot
• Light intensity increases


  Rate of photosynthesis increases (up to a point)
• Even when the graph is flat, there is still a steady rate of photosynthesis
• The actual rate of photosynthesis depends on many different factors
• Glucose from photosynthesis


  Stored as starch, with potatoes being an obvious example
• Leaf structure


  • Palisade mesophyll (photosynthesis), cuticle, upper and lower epidermis, spongy mesophyll (gas exchange), guard cells and stomata (transpiration)
• Xylem


  Carries water upwards from roots to leaves
• Phloem


  Carries ions and food downwards from leaves to roots
• Factors affecting rate of transpiration

  • Bright light
  • High temperature
  • High wind
  • Low humidity
• Parts of the endocrine system

  • Pituitary gland
  • Thyroid
  • Adrenal glands
  • Pancreas
  • Ovaries
  • Testes
• Testosterone


  Produced by testes, has effects like growing muscles, making genitals grow, increasing hair growth
• Estrogen


  Produced by ovaries, responsible for egg maturation and menstrual cycle
• Insulin


  Produced by pancreas, important for regulating blood glucose levels
• Adrenalin


  Produced by adrenal glands, part of the fight or flight response
• Thyroxine


  Produced by thyroid, important in regulating metabolism
• Follicle stimulating hormone (FSH) and luteinizing hormone (LH)

  Produced by pituitary gland, important for egg maturation and release
• Contraception methods

  • Condoms (barrier)
  • Pill (hormonal)
  • Coil/IUD (hormonal)
  • Diaphragm (barrier)
  • Sterilization (permanent)
• Around one in six people have difficulty conceiving naturally
• IVF


  Involves taking many drugs with nasty side effects, is very expensive, and has a 40% success rate
• Homeostasis is the maintenance of a constant internal environment
• Brain


  The control center for homeostasis, sending signals to other parts of the body
• Control of blood glucose levels

  Blood glucose rises after a meal → Pancreas produces insulin → Insulin causes cells to remove glucose from blood → Blood glucose falls → If too low, pancreas produces glucagon → Stored glycogen converted to glucose and returned to blood
• Type 1 diabetes


  Pancreas doesn't produce enough insulin
• Type 2 diabetes


  Cells become insensitive to insulin
• Symptoms of both types of diabetes include weight loss, increased urination, thirst, blurred vision, fatigue, and hunger
• Diffusion


  Movement of substances from high concentration to low concentration down a concentration gradient
• Glycogen


  Stored form of glucose in muscle and liver cells
• Glucagon converting glycogen into glucose


  Causes blood glucose levels to rise again
• Type 1 diabetes


  Pancreas doesn't produce the right amount of insulin
• Symptoms of diabetes


  • Loss of weight
  • Increased need to urinate
  • Increased thirst
  • Blurry vision
  • Fatigue
  • Hunger
• Treatment for type 1 diabetes

  Insulin injections
• Treatment for type 2 diabetes

  Controlling diet, exercise