The role of plants in their natural environment is to absorb excess carbon dioxide and produce oxygen to replace the CO2 in the air. Carbon dioxide is harmful because it is toxic and because it is one of the gases that causes the greenhouse effect. Oxygen is essential to life and it also forms ozone (O3), which protects earth's inhabitants from ultraviolet rays.
2. Photosynthesis involves a series of chemical reactions, where the product of the first reaction is used as a reactant in the second, and so on. This is called a biochemical pathway. This pathway can be broken down into three steps.
1) CO2 diffuses into the stroma from the cytosol. An enzyme then reacts with the CO2 and combines it with a molecule known as RuBP. Product immediately splits into 2 molecules called PGA.
2) The PGA is then converted into PGAL by receiving a phosphate group from an ATP molecule and a proton from NADPH.
3) Most of the PGAL is converted back into RuBP, releasing energy. But some is sent to other parts of the plant cell to make other organic compounds.
3. Photosynthesis and cellular respiration both involve the absorption of gases and the release of a by-product, but photosynthesis involves the absorption of carbon dioxide and water and the release of organic compounds and oxygen, while respiration is exactly the opposite. The amount of CO2 in the are will also affect photosynthesis, since CO2 is imperative to photosynthesis.
4. Factors affecting photosynthesis would be light intensity and temperature. As light intensity increases, the rate of photosynthesis increases rapidly and then levels off at a maximum. As temperature increases, the rate of photosynthesis increases, levels off, and then declines at the same rate.
5. Adaptations that maximize conditions for photosynthesis would be the plants that arrange their leaves in different ways so that most of them are available to the sunlight. Another would be that all plants grow towards the sun.