B4 Quizzlet

• What do plants use for their source of energy?

  light
• What is photosynthesis?


  The reaction where plants capture light energy and uses it to make food
• Is photosynthesis exothermic or endothermic? Why?

  Endothermic

  because they take in (light) energy

  & more energy is needed to BREAK the bonds that binds CO2 & H20 molecules together

  than the energy needed to MAKE the bonds of O2 & C6H12O6
• Where does photosynthesis take place?

  Leaves (chloroplast→ chlorophyll)
• Word equation for photosynthesis

  Carbon dioxide + water → glucose + oxygen (w/ light)
• Symbol equation for photosynthesis

  6H₂O + 6CO₂ → C₆H₁₂O₆ + 6O₂
• What is a limiting factor?


  A factor which, if in short supply, limits or reduces the rate of a reaction (photosynthesis in this case)
• Limiting factors of photosynthesis

  light intensity

  carbon dioxide concentration

  temperature

  amount of chlorophyll
• As light intensity increases, the rate of photosynthesis

  increases

  
• As CO2 concentration increases, the rate of photosynthesis

  increases

  
• Explain how light intensity & CO2 concentration affect the rate of photosynthesis

  Like in the graph:

  
• Where does a plant get CO2 and water from for photosynthesis?

  Atmosphere

  Soil
• How does temperature affect the rate of photosynthesis?

  Rate of photosynthesis increases w/ tterm-21emp.

  until it reaches optimal temp.

  where enzymes become denatures (normally around 40-50 degrees celcius)

  and photosynthesis ceases (no photosynthesis)
• When would light intensity be more limiting than other factors? Why?

  At night

  on cloudy/dark days

  b/c no light or lack of it
• When would temperature be more limiting than other factors?

  Cold days

  b/c temp. is low
• Why is CO2 conc. often the limiting factor of photosynthesis?

  B/c only about 0.04% of the atmosphere is CO2
• When would CO2 conc. be more limiting than other factors?

  On a warm, sunny day

  b/c light intensity & temp. will be at optimum levels
• What does iodine test for?

  starch (blue-black)
• What does magnesium do in plants?

  Makes chlorophyll
• Ways that farmers can get a greater rate of photosynthesis, and therefore a greater yield of crops

  Hydroponics

  Greenhouses

  (b/c you can control factors that affect rate of photosynthesis)
• Main benefit of artificially manipulating environment in which food plants are grown (e.g. greenhouses, hydroponics)

  Rate of photosynthesis will be at highest

  w/o having to rely completely on nature (as you can control the conditions of the environment)

  and temp. is higher inside than outside
• Why do farmers want to increase the rate of photosynthesis?

  To get a greater yield (of crops)
• What do greenhouses do to make the plant grow faster?

  Control all the limiting factors
• What are hydroponics?


  The plants are grown in water

  with a perfect balance of mineral ions instead of soil

  to make sure nothing slows their growth
• Advantages of hydroponics (9 things)

  Crops are clean & soil free

  Don't need to plough fields

  Fast yield (which means profits are high)

  Crops can be grown where the land in poor

  Mineral levels can be controlled more accurately

  Diseases can be controlled more effectively

  no weeds,

  no outdoor pests,

  can use in space and underwater exploration
• What could you control in greenhouses AND hydroponics to increase the rate of photosynthesis?

  The mineral content in the water

  (as theterm-24 plant grows)
• How can oil burners help gardeners in greenhouses?

  They release CO2 & heat at the same time
• Advantages of greenhouses


  Less staff needed

  Faster yield

  Final crops are larger
• Disadvantage of greenhouses to increase rate of photosynthesis and how it should be solved


  Expensive (so extra cost has to be justified by increase in yield)
• As the distance of the light from the plant increases...

  light intensity decreases
• Light intensity is inversely proportional to


  distance squared/square of the distance
• 6 uses of glucose from photosynthesis

  1) Used for respiration

  2) Convert to INSOLUBLE starch for storage

  3) Produce fats or oils for storage

  4) Produce cellulose (for cell wall)

  5) Produce amino acids for protein synthesis

  6) Growth and repair
• What are fats and oils used as by plants?

  Storage form of energy
• What does cellulose do in plants?


  Strengthens the cell wall.
• What do amino acids do in plants?

  Synthesise proteins
• How do plants produce amino acids from glucose?

  By combining sugars with nitrate and other mineral ions from the soil
• What is needed to make amino acids from glucose in plants? Where does this come from?

  Nitrate ions (+other mineral ions)

  from the soil
• Where do algae get their mineral ions from to produce amino acids?


  From the water they live in
• Why is some of the glucose made by photosynthesis converted into starch?

  B/c starch is insoluble

  and can be stored (for future) and converted back into glucose by the plant when it's needed (e.g. at night)

  and b/c glucose is soluble,

  (it would affect the way water moves in & out of cells by osmosis, and therefore the overall water balance of the plant)

  and starch is insoluble

  it would have no affect on the water balance of the plant

  so plants can store large amounts of it in their cells
• What is potato high in?

  Starch