Teacher Information Sheet: Photosynthesis

Posted By on Dec 16, 2013


Palm leaf in Mexico

Palm leaf in Mexico

1. What does photosynthesis mean? You may be able to figure it out just by looking at the prefix photo and the root word synthesis. 

When looking at the word photosynthesis, I can see photo and synthesis. When you think of photo, what do you think of? Photo means light. When you think of synthesis, what do you think of? Do you think synthesis means putting something together, or pulling it apart? Synthesis means putting together. So, if we combine or synthesize photo and synthesis, what does photosynthesis mean? Yes, photosynthesis means putting together light.

2. What are the major players in photosynthesis? In other words, photosynthesis consists of what major components?

If photosynthesis depends on light, what is our planet’s major source of light? Yes, sunlight from the sun. So the sun is one of the major players in photosynthesis. Additional major players in photosynthesis are trees and green plants.

3. How important is the sun in photosynthesis and what role does it play?

Did you know that the sun is a star? It is essentially a huge ball of hot gas (hydrogen and helium) that undergoes nuclear reactions. It is located at the center of our solar system and provides energy in the form of sunlight and heat to our planet. Without the sun, plants and animals could not exist.
4. How important are trees and green plants in photosynthesis and what role do they play?

Did you know that trees are often referred to as the lungs of the planet? Why do you think that is? Basically, trees and green plants absorb carbon dioxide (a greenhouse gas) and produce oxygen upon which all animals depend on for survival. Rainforests play a huge and critical role in the amount of oxygen in Earth’s atmosphere. Even though they cover less than 2 percent of Earth’s surface, rainforests house more than 50 percent of the plants and animals on Earth! Note: This incredible diversity of life (biodiversity) will be discussed in Lesson 3.

5. Can you describe the process of photosynthesis? What happens first, second, third, etc? (Sketch each step on the board as you discuss each one)

First: Trees and plants absorb: (a) water from the ground through their roots; (b) carbon dioxide from the air through tiny openings on the underside of leaves called stomata; and (c) sunlight from the sun by tiny organelles on the surface of leaves called chloroplasts.
Second: These chloroplasts contain chlorophyll (a green pigment). When
sunlight shines on the surface of a leaf, the light energy is trapped by the
chlorophyll. This energy is used to drive chemical reactions.
Third: This chemical reaction consists of carbon dioxide (absorbed through
stomata) and water. [Note: When the stomata open to absorb carbon dioxide, they also lose water (transpiration, Lesson 1).] However, water absorbed from tree and/or plant roots and carbon dioxide undergo a chemical reaction and are converted (synthesized) into sugar and oxygen. Both oxygen and water are released into Earth’s atmosphere and
the sugar remains inside the tree and/or plant leaves. Trees and plants use sugar as energy and store the rest.
6. How and why is photosynthesis important to our planet?

Like the water cycle (Lesson 1), photosynthesis is one of the driving forces of life on our planet. Since rainforests are located along the equator (show map or globe) they receive approximately 12 hours of sunlight each day all year round. So, we can surmise that perhaps rainforests have a higher rate of photosynthesis, which means they absorb more carbon dioxide and emit more oxygen and water into Earth’s atmosphere. Planet earth would not be able to sustain life without oxygen and water. Plants are dependent on photosynthesis in addition to all animals.
7. How and why is photosynthesis important to animals?

All animals depend on both sugar (glucose) and oxygen for their survival.
Without glucose and oxygen, the brain simply cannot survive. And without a
brain, an animal cannot survive.
8. Could we live without photosynthesis? Why? Explain your answer.

No, we could not live without photosynthesis because all life is dependent on
the sun. Without the sun, the process of photosynthesis could not occur.
Without photosynthesis, there would be no plants. Without plants, there would be no animals (that includes humans).
9. What would happen if the process of photosynthesis became disrupted, i.e., loss of trees due to deforestation (cutting down forests), too much carbon dioxide due to burning non-renewable sources of energy (oil, gasoline, coal) and wood?)

The quality of life for all animals would suffer significantly. There would be less oxygen in Earth’s atmosphere and more carbon dioxide from the loss of trees and burning of fossil fuels. The air pollution would become unbearable. More people would most likely develop respiratory problems (asthma) and other illnesses. In addition to air pollution, water pollution would occur as well. Basically the water would become more acidic which is harmful, if not deadly, to aquatic plants and animals.
10. Is there anything human beings can due to decrease the amount of carbon dioxide released into Earth’s atmosphere? Why is this important?

We must use our brains to invent creative solutions using renewable forms of energy (solar, wind, geothermal, etc) rather than the old, archaic, traditional forms we are still using today (oil, gasoline, coal, nuclear, burning wood, etc.) There are solutions. We just need to work together and think ‘outside the box’ to find them.

References:

  • Rainforests by Rhett Butler copyright 2011
  • http://www.biology4kids.com/files/plants_photosynthesis.html
  • http://meridianacademy.org/parents_&_students/hw_portal/mst/documents/Photosynthesis.pdf
  • PDF Version