(modified from http://www.hobart.k12.in.us/jkousen/Biology/phobig.html)
PHOTOSYNTHESIS - Q and A
What is photosynthesis?
Exactly why is photosynthesis so important?
What is photosynthesis?
- Photosynthesis is a chemical reaction in which light energy is converted to chemical energy in glucose. It is the means by which the energy in sunlight becomes usable to most living things. Heterotrophs can eat glucose, but we can't eat sunlight.
Exactly why is photosynthesis so important?
- Two big reasons. One product of photosynthesis is glucose (sugar), which provides the basis for most food chains. The second product of photosynthesis is oxygen which comes in handy if your happen to be an organism that requires oxygen for survival.
Where does photosythesis occur?
What raw materials are needed for the process of photosynthesis?
To which "life function" is photosynthesis related?
How can we summarize photosynthesis?
What else should we remember about photosynthesis?
- This question can be answered on various levels:
- In terms of organisms, photosynthesis occurs in autotrophes that contain the green pigment chlorophyll. This would include the entire Plant Kingdom and approximately half of the Protists Kingdom (the algae)
- On the multicellular level, photosynthesis occurs in the leaves of plants.
- On the cellular level, the reactions for photosynthesis occur in organelles called chloroplasts (in eukaryotic cells). Blue-green algae (which are prokaryotic) carry-out the photosythesis reactions in the cytoplasm since they do not have membrane-bound organelles.
What raw materials are needed for the process of photosynthesis?
- As mentioned above, chlorophyll must be present. (Chlorophyll absorbs solar energy).
- Sunlight is necessary. That's why we call it PHOTOsynthesis. (PHOTO = light; SYNTHESIS = to put together with)
- From the environment, photosynthetic organisms must get water & carbon dioxide.
- Therefore, in order for photosynthesis to take place, plant need: chlorophyll, sunlight, water, and carbon dioxide
To which "life function" is photosynthesis related?
- Photosynthesis falls under nutrition, autotrophic nutrition to be exact. Nutrition has to do with how organisms obtain the materials necessary for energy, growth, etc. We call these necessary materials nutrients.
- "Autotrophic" means that the organism makes the nutrients on its own using materials in the environment
How can we summarize photosynthesis?
- In words, remember this:
- As a chemical reaction it looks like this:
What else should we remember about photosynthesis?
- Well, it's an important component of the Oxygen-Carbon Dioxide Cycle.
- Organisms that carry-out photosynthesis are like oxygen factories. At the same time they are removing CO2 from the atmosphere.
- Increasing levels of CO2 appear to go hand in hand with increasing global temperature ("Global Warming"). So damaging the ecosystems where photosynthesis occurs (i.e. the rainforests, the oceans) reduces the amount of oxygen being pumped into the air (that's a bad thing) & slows the rate at which carbon dioxide is removed from the atmosphere (which also appears to be a bad thing).