PAPER 2 - SUMMARY

• What is the purpose of leaves in plants?

  Photosynthesis and transpiration occur in leaves
• What do roots do in plants?

  Roots absorb water and mineral ions
• What is the function of xylem in plants?

  Xylem transports water unidirectionally upwards
• What is the function of phloem in plants?

  Phloem transports sugars bidirectionally
• What factors can increase the rate of transpiration?

  Higher temperature, lower humidity, increased air movement
• What are the layers of a leaf and their functions?

  • Waxy cuticle: Prevents water loss
  • Upper epidermis: Allows light penetration
  • Palisade mesophyll: Main site of photosynthesis
  • Spongy mesophyll: Gas exchange
  • Vascular bundle: Contains xylem and phloem
  • Lower epidermis: Contains stomata for gas exchange
• What controls the size of stomata in leaves?

  Guard cells control the size of stomata
• What type of reaction is photosynthesis?

  Photosynthesis is an endothermic reaction
• What can glucose produced in photosynthesis be used for?

  Respiration, starch, fat, cellulose, amino acids
• What factors can limit the rate of photosynthesis?

  Light intensity, temperature, CO₂ concentration
• How can the rate of photosynthesis be measured practically?

  By measuring oxygen production from pondweed
• What is the relationship between light intensity and distance?

  Light intensity follows an inverse square relationship
• What role do gibberellins play in plants?

  They promote seed germination and flowering
• What is the function of ethylene in plants?

  Ethylene induces ripening of fruits
• What is phototropism in plants?

  Growth towards light due to auxins
• What is geotropism in roots?

  Roots grow downwards due to auxins
• What is homeostasis?

  Regulation of internal conditions in organisms
• What is thermoregulation?

  Control of internal body temperature
• How does the body respond when too hot?

  Sweating and vasodilation occur
• How does the body respond when too cold?

  Shivering and vasoconstriction occur
• What is the role of the endocrine system?

  Produces hormones that regulate body functions
• What is the function of the pituitary gland?

  It is the master gland producing hormones
• What hormone does the pancreas produce?

  The pancreas produces insulin
• What happens when blood glucose levels are too high?

  Insulin moves glucose into cells for respiration
• What happens when blood glucose levels are too low?

  Glucagon converts glycogen back to glucose
• What is type 1 diabetes?

  Insufficient insulin production by the pancreas
• What is type 2 diabetes?

  Cells do not absorb glucose properly
• How does the body maintain water balance?

  Kidneys regulate water levels in the blood
• What is the role of kidneys in water balance?

  Kidneys filter blood and produce urine
• What is the function of adrenaline?

  Increases heart and breathing rate in stress
• What does thyroxin control?

  Thyroxin controls metabolic rate
• What is negative feedback?

  Response that returns conditions to normal
• What is the role of ADH in the kidneys?

  ADH increases water reabsorption in kidneys
• What happens if kidneys fail?

  Dialysis is required to filter blood
• What initiates the menstrual cycle?

  FSH causes eggs to mature in ovaries
• What does estrogen do in the menstrual cycle?

  Thickens the uterus lining and inhibits FSH
• What does LH do in the menstrual cycle?

  Causes the egg to be released from the ovary
• What is the purpose of progesterone in the menstrual cycle?

  Maintains the uterus lining for pregnancy
• What are some contraception methods?

  Pills, injections, condoms, IUDs
• What is IVF?

  Fertilization of eggs in a lab for pregnancy