Plant structures & functions

• What are the main producers of food through photosynthesis?

  Plants and algae
• What is the process by which plants and algae synthesize food from sunlight?

  Photosynthesis
• What type of reaction is photosynthesis?

  It is an endothermic reaction
• Where does photosynthesis occur in plants?

  In chloroplasts
• What is the equation for photosynthesis?

  Light + carbon dioxide + water → glucose + oxygen

  
• What is the chemical symbol for carbon dioxide?

  CO₂

  
• What is the chemical symbol for water?

  H₂O
• What is the chemical symbol for oxygen?


  O₂
• What is the chemical formula for glucose?

  C₆H₁₂O₆
• What factors affect the rate of photosynthesis?

  • Temperature
  • Light intensity
  • Carbon dioxide concentration

  
• What is a limiting factor in photosynthesis?

  An environmental condition that restricts the rate of photosynthesis at low levels
• How does temperature affect the rate of photosynthesis?

  It increases the rate up to a certain point, after which enzymes denature
• How does light intensity affect the rate of photosynthesis?

  Higher light intensity generally increases the rate of photosynthesis

  
• What happens to the rate of photosynthesis as carbon dioxide concentration increases?

  The rate of reaction increases

  
• What is the procedure to measure the rate of photosynthesis using oxygen production?

  1. Place pondweed in a sealed test tube with water.

  2. Use a capillary tube and syringe to measure oxygen production.

  3. Position a lamp at a measured distance.

  4. Measure the distance the oxygen bubble moves.

  5. Change variables like temperature and light intensity.

  
• What is the purpose of controlling variables in an experiment measuring photosynthesis?

  To ensure a valid experiment
• How can a graph indicate a limiting factor in photosynthesis?

  If it has one line that levels off
• What does a graph with two lines represent in terms of limiting factors?

  Two limiting factors in two experiments
• What does the inverse square law state about light intensity and distance?

  Light intensity is inversely proportional to the square of the distance
• If a lamp is 2 meters away from a plant, what is the light intensity compared to its original value?

  It is a quarter of its original value
• What are the adaptations of root hair cells?

  • Large surface area due to root hairs
  • Large permanent vacuole for water movement
  • Mitochondria for energy from respiration
• What are the adaptations of xylem cells?

  • Lignin causes cells to die and become hollow
  • Joined end-to-end to form continuous tubes
  • Lignin deposited in spirals for pressure resistance
• What are the adaptations of phloem cells?

  • Sieve plates for substance movement
  • Cells are alive
  • Energy supplied by companion cells' mitochondria
• What is transpiration?


  The loss of water vapor from the leaves and stems of the plant
• How does transpiration occur in plants?

  Water evaporates at open stomata, pulling more water up through the xylem
• What are the functions of guard cells?

  • Open and close stomata
  • Kidney-shaped with thin outer walls and thick inner walls
  • Respond to water availability and light
• What is translocation in plants?


  The movement of food substances through the phloem
• Where does translocation occur in plants?


  Only in the phloem
• What are sources and sinks in the context of translocation?

  Sources are where substances are made, and sinks are where they are used or stored
• How can the location of sources and sinks change with the seasons?

  In spring, the source could be in the root and the sink in the leaf, and vice versa in summer
• What are the adaptations of leaves for photosynthesis?

  • Broad surface area for light absorption
  • Thin structure for gas exchange
  • Contain chlorophyll for capturing light energy
• What is the process by which water leaves the plant?

  Evaporation
• Where are more stomata typically found on a leaf, and why?

  More stomata are found on the bottom of the leaf to minimize water loss by evaporation.
• What is translocation in plants?

  Translocation is the movement of food substances, such as sucrose, in the phloem.
• In which part of the plant does translocation occur?

  Translocation occurs only in the phloem.
• What are the sources and sinks in the context of translocation?


  Sources are where sucrose is made, and sinks are where it is used or stored.
• How can the location of sources and sinks change with the seasons?

  In spring, the source could be in the root and the sink in the leaf, while in summer, this could reverse.
• What are the adaptations of leaves for photosynthesis?

  • Stomata: Close to minimize water loss and open for gas exchange.
  • Chlorophyll: Green pigment that absorbs light efficiently.
  • Thinness: Short distance for gas diffusion.
  • Large surface area: Maximizes light absorption.

  
• How does an increase in temperature affect transpiration?

  An increase in temperature causes molecules to move faster, increasing the rate of evaporation and transpiration.
• What happens to the rate of transpiration when relative humidity increases?

  Higher relative humidity reduces the concentration gradient, resulting in a slower rate of transpiration.