Plants and photosynthesis

• What is the function of leaves in plants?

  Photosynthesis and transpiration
• How does transpiration occur in plants?

  Water evaporates from leaves
• What do roots do in plants?

  Absorb water and mineral ions
• What is the role of xylem in plants?

  Xylem transports water unidirectionally
• What is translocation in plants?

  Transport of sugars up and down
• What factors can increase the rate of transpiration?

  Higher temperature, lower humidity, more air movement
• What is the function of the waxy cuticle on leaves?

  Prevents water loss through evaporation
• What is the role of the palisade mesophyll layer?

  Site of most photosynthesis due to chloroplasts
• What is the function of the spongy mesophyll layer?

  Facilitates gas exchange with gaps
• What are stomata?

  Holes for gas exchange on leaves
• How do guard cells regulate stomata?

  Change size to control gas exchange
• What is the balanced chemical equation for photosynthesis?

  6CO'2 + 6H'2O → C'6H'12O'6 + 6O'2

  Carbon dioxide + water → glucose + oxygen
• What type of reaction is photosynthesis?

  Endothermic reaction requiring light energy
• What happens to glucose produced in photosynthesis?

  Used for respiration, stored as starch or fat
• What factors can limit the rate of photosynthesis?

  Light intensity, temperature, CO2 concentration
• How can we measure the rate of photosynthesis practically?

  By measuring oxygen production in pondweed
• What is the inverse square relationship in light intensity?

  If distance doubles, light intensity quarters
• What are gibberellins in plants?

  Hormones that promote seed germination and growth
• What is the role of ethylene in plants?

  Induces ripening of fruits
• What is phototropism?

  Growth towards light due to auxins
• What is geotropism?

  Growth response to gravity in roots