Respiration vs Photosynthesis

By Celine Leong, Marion Bregiannis and Laura Mason.

^^ is the link to our presentation.

* Give the equation for each with a detailed explination.
Chemical equation:

6CO2 + 6H20 + Energy -----> C6H12O6 + 6O2
Worded equation:
Carbon Dioxide + Water + Sunlight ----> Glucose + Oxygen

Photosynthesis is the process of converting light to chemical energy and storing it on the bonds of sugar.

Chemical Equation:

C6H12O6 + 6O2 -------> 6CO2 + 6H2O + Energy
Worded Equation:
Glucose + Oxygen -----> Carbon Dioxide + water + Energy

Respiration is when plants and animals convert starch that has been stored into energy. It is the process where organisms release energy from food.

*Some numbers in the chemcial equations could not be written in correct format.

Though the equations for photosynthesis and respiration are similar, the processes for the two differ immensely. They both use a different sequence of steps, different enzymes and different locations of occurance.

* Use labelled digrams to explain where and how the reactions occur in a plant.
Photosynthesis can only be carried out in plants. It is when the plant makes its own food, called glucose, by combining carbon dioxide from the air and water from its roots. It also must include chlorophyll, the green pigment in plants, which is also the cause of most plants to be green. Photosynthesis is split into two reactions; the first being the light reaction and the second being dark reaction. In the light reaction, the lights energy is changed to a chemical energy. In the dark reaction, glucose is formed by an enzyme-controled reaction when carbon dioxide and hydrogen ions combine.
In respiration, plants (and animals) convert the sugars back into energy. The chemical equation for respiration is the opposite of the equation for photosynthesis. It shows that the sugars from photosynthesis are combined with oxygen instead of using carbon dioxide from the air and water from the soil react with the sun’s energy to form carbohydrates (sugars and starches).
external image photosynthesis1.gifexternal image photosynthesis.gif

*Explain how each of the reactions occur-ie factors affecting their rates.
The availability of carbon dioxide, the amount of light available, the amount of availability of water, the amount of nutrients available and the temperature can all affect the rate of photosynthesis. If any of these factors are increased or decreased, then the same would generally happen to the rate of photosynthesis. The photosynthesis rate rises quickly if the light intensity is raised as there is more energy accessible. However, once it reaches a certain point, the increasing of the rate of photosynthesis is halted; and this leads to carbon dioxide limiting the reaction. The carbon dioxide then decides the maximum rate of photosynthesis after levelling out the different rates of photosynthesis. Once the temperature reaches 30 C, the rate of photosynthesis is decreased as enzymes are affected by higher temperatures and therefore cannot function properly. The rate of photodynthesis is highest during the day (with sunlight) and lowest at night. Photosynthesis may occur up to ten times faster than respiration on sunny days. In comparison, the photosynthesis rate at night is severely less than the respiration rate at night as there is no sunlight to help photosynthesis