photosynthesis

• photosynthesis is an endothermic reaction which means energy that is transferred from the surroundings to the reaction
• the word equation for photosynthesis is carbon dioxide + water = glucose + oxygen
• the symbol equation for photosynthesis is 6CO(2)+6H(2)O=C(6)H(12)O(6)+6O(2)
• chlorophyll is a pigment that is found in the chloroplasts of green plants. they absorb energy from light which is used to make glucose
• photosynthesis is an endothermic reaction used by plants to make their own food. Energy is required in the form of sunlight.
• solar energy is absorbed by chlorophyll in the chloroplasts of the leaf. this energy is used to convert carbon dioxide and water into oxygen and glucose
• there are three factors that can affect the rate of photosynthesis: light intensity, temperature and concentration of carbon dioxide
• as light intensity increases so does photosynthesis although eventually the graph stops going upwards and begins to form a straight line, this is because the maximum amount of light has been reached as well as the limit of photosynthesis.
• the temperature increases the rate of photosynthesis until the enzymes begin to lose energy at 40 degrees then they begin to denature ,meaning the active site changed shape and cannot function, at the optimum temperature.
• if there is plenty of light lots of photosynthesis can take place. but if there is little to no light photosynthesis will stop or decrease.
• temperature can affect all chemical reactions. as temp rises the rate of photosynthesis increases as the reaction speeds up. however photosynthesis is controlled by enzymes. Most enzymes denature once the temp reaches 40-50 degrees after this the rate will drop
• as the level of carbon dioxide rises the rate of photosynthesis will increase. On a sunny day the most likely limiting factor is the co2 concentration. The concentration tends to rise at night because plants are respiting not photosynthesising.
• to calculate light intensity we can use the inverse square law the equation for this is I is proportional to 1/d^2 d=distance measure in metres and I=intensity measure in arbitrary units (A.U)
• the word equation for photosynthesis is carbon dioxide + water = (sunlight, chlorophyll) glucose + oxygen
• photosynthesis is an endothermic reaction as it takes in energy from the environment to the chloroplasts by light
• glucose produced in photosynthesis can be used for respiration, making starch, making cellulose, producing proteins and making fat and oils
• to produce proteins plants also need nitrate ions that are absorbed from the soil
• the bigger the rate go photosynthesis the faster the plant can grow causing the biomass to also increase
• the less chlorophyll in a leaf the less photosynthesis
• a leaf may have less chlorophyll because of tobacco mosaic virus or if the plant doesn't have enough mineral ions
• explain the graph for light intensity factors on photosynthesis

  . at low light intensities the increase in the rate of photosynthesis is linear

  . at one point the factor become limiting

  . the graph levels off and the rate becomes constant
• explain co2 concentration and its graph

  .the same as light intensity graph

  .at some point the factor becomes limiting and stays constant
• explain the graph for temperature and its limiting factor

  At low temperatures, the rate of photosynthesis is limited by the number of molecular collisions between enzymes and substrates. At high temperatures, enzymes are denatured causing the graph to fall
• why are limiting factors important in green housing?

  .Levels of carbon dioxide in the atmosphere are rising because of greenhouse gas emissions. They are currently at around 0.04 per cent. This concentration is still very low in terms of being the optimum for photosynthesis.

  .Most scientists think that with rising temperatures, crop production will be negatively affected by climate change.
• why is light important when growing plants?

  Increasing the light intensity in greenhouses will increase the growth of crop or horticultural plants.

  Plant growers can:

  • use greenhouses constructed from glass or alternative materials that enable maximum transmission of light
  • position plants for maximum light absorption

  Artificial lighting systems can be used:

  • with increased light intensities
  • that provide optimum wavelengths of light for photosynthesis
  • that lengthen a plant's growing season so that crops can be grown in more months of the year
• what is the glucose used for in plants?

  respiration They break down glucose and the chemical energy thus released is used by the plant for other cellular activities