Biology paper 2 plant structures and their functions

• What is the process by which plants make their own food?

  Photosynthesis
• What are the raw materials for photosynthesis?

  Carbon dioxide and water
• What is the chemical equation for photosynthesis?

  6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• What are the limiting factors in photosynthesis?

  • Light intensity
  • CO₂ concentration
  • Temperature
• How does light intensity affect the rate of photosynthesis?

  Increases rate until a certain point
• What happens to the rate of photosynthesis when light intensity is increased beyond a certain point?

  The rate increases slowly and plateaus
• What is the relationship between distance from a light source and light intensity?

  They are inversely proportional
• What is the formula for the inverse square law regarding light intensity?

  1/d²
• If the distance from a lamp is halved, how does light intensity change?

  It becomes four times greater
• What happens to light intensity at 20 cm from the lamp?

  0.0025 arbitrary units
• What is the effect of too little carbon dioxide on photosynthesis?

  It slows down the rate
• What happens to the rate of photosynthesis when CO₂ concentration is increased?

  Increases until a certain point
• What is the role of temperature in photosynthesis?

  It must be optimal for enzyme activity
• At what temperature do enzymes in plants typically start to denature?

  About 45°C
• What is transpiration in plants?

  The loss of water from the plant
• What do root hairs do in plants?

  Take up water
• What are the functions of phloem and xylem in plants?

  • Phloem: Transports food from leaves
  • Xylem: Carries water from roots
• What is the main purpose of stomata in plants?

  Gas exchange
• How does transpiration affect water uptake in plants?

  It draws more water from roots
• What are auxins?

  Plant growth hormones
• Where are auxins produced in plants?

  At the tip of shoots and roots
• How do auxins affect shoot growth?

  They promote elongation on the shaded side
• What is the effect of auxins on root growth?

  They inhibit elongation on the shaded side
• How can you investigate plant growth responses to light?

  1. Use cress seeds in a Petri dish
  2. Surround with black card
  3. Create a hole for light
  4. Measure growth towards light
• What is the purpose of plant growth regulators (PGRs)?

  To control plant growth and functions
• How do PGRs help in reducing fruit drop during transit?

  They prevent leaf loss after cutting
• How can PGRs affect the ripening of fruits?

  They can slow or hasten ripening
• What is the effect of treating seeds with chemicals?

  Helps them germinate under right conditions
• What is the significance of uniform crop production?

  Ensures consistent quality and yield