plant structures and their functions

• What is the process of photosynthesis


  A chemical reaction that takes place inside photosynthetic organisms (e.g. plants and algae) converting light energy into chemical energy
• Why are plants called producers 


  Because they produce their own food
• What are photosynthetic organisms


  Main producers of food and therefore biomass
• What is biomass


  The mass of living material at a particular stage in a food chain
• Photosynthesis equation

  Carbon dioxide + water = glucose + oxygen
• Symbol equation for photosynthesis

  $6CO_2\ +$$\ 6H_2O\ \rightarrow\ C_6H_{12}O_6\ +$$\ 6O_2$
• Why is photosynthesis important?

  used in respiration to release energy, converted to starch and stored and used to make complex molecules which are used for growth, making up an organisms biomass
• Where does photosynthesis take place

  Within chloroplasts
• what is chlorophyll

  a pigment found in chloroplasts that absorbs light
• two main stages of photosynthesis

  1. chlorophyll absorbs light energy which is used to split water into oxygen gas (waste products) and hydrogen ions
  2. carbon dioxide combines with hydrogen ions to form glucose
• what factors affect the rate of photosynthesis

  • temperature
  • light intensity
  • carbon dioxide concentration
• what is a limiting factor

  a variable that limits the rate of a particular reaction
• how does temperature affect rate of photosynthesis

  • higher temp provides more KE for enzymes involved so rate increases as temp rises
  • optimum is usually 25*c , so too high enzymes become denatured and the rate is decreased
• how light intensity effects rate of photosynthesis

  rate of photosynthesis is directly proportional to light intensity
• why does rate of photosynthesis plateau even if light intensity continues to increase

  another factor (temperature or C02 concentratio) becomes limiting
• how can the effect of light intensity on the rate of photosynthesis be measured in the lab?

  light meter, inverse square law
• how carbon dioxide concentration affects the rate of photosynthesis

  as carbon dioxide concentration increase, the rate of photosynthesis increases
• What are the main producers of food in ecosystems?

  Plants and algae
• What process do plants and algae use to synthesize food?

  Photosynthesis
• What type of reaction is photosynthesis?

  Endothermic reaction
• Where does photosynthesis occur in plants?

  In chloroplasts
• What is a limiting factor in photosynthesis?

  An environmental condition restricting photosynthesis
• How does temperature affect the rate of photosynthesis?

  Increases rate until enzymes denature
• How does light intensity affect photosynthesis?

  Higher intensity increases the reaction rate
• How does carbon dioxide concentration affect photosynthesis?

  Higher concentration increases the reaction rate

  
• What happens to the rate of photosynthesis when one factor is limiting?

  The rate levels off despite other factors increasing
• What is the experimental setup to measure the rate of photosynthesis using pondweed?

  • Place pondweed in a sealed test tube with water
  • Use a capillary tube and syringe to measure oxygen
  • Position a lamp at a fixed distance
  • Measure oxygen production over time
• What is the purpose of the capillary tube in the photosynthesis experiment?

  To measure oxygen production
• What does a graph with one line leveling off indicate?

  One limiting factor affecting photosynthesis
• What does a graph with two lines represent?

  Two limiting factors in two experiments
• How is light intensity measured in experiments?

  In lux
• How can farmers use knowledge of limiting factors?

  To enhance greenhouse conditions for growth
• What is the setup for measuring the rate of photosynthesis in a simple experiment?

  Sealed flask, gas syringe, pondweed, lamp
• What is the inverse square law in relation to light intensity?

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

  1/4 of its original value
• What are the adaptations of root hair cells?

  • Large surface area for water uptake
  • Large permanent vacuole for water movement
  • Mitochondria for energy in active transport
• What are the adaptations of xylem cells?

  • Lignified dead cells for water transport
  • Hollow structure for continuous flow
  • Spiral lignin for pressure resistance
• What are the adaptations of phloem cells?

  • Sieve plates for substance movement
  • Living cells for transport functions
  • Companion cells provide energy for transport
• What is transpiration?

  Loss of water vapor from plants
• How does transpiration occur?

  Water evaporates through open stomata