Describe the importance of Photosynthesis for life on Earth

A WebQuest for 8th Grade (Botany)

Designed by

John Ringold

Introduction | Task | Process | Evaluation | Conclusion | Credits


Photosynthesis is one of the most basic life processes on earth.  It may have been one of the characterisitics of some early life to evolve.  Understanding how photosynthesis impacts the rest of life  on the planet is important to understanding the global ecology of today.  The majority of organisms the conduct photosynthesis reside in the ocean and are not trees.

The Task

Using what you already know about climate chemistry and the websites listed below; I want you to offer a prediction as to the consequences if the Earth suddenly had twice as many photosynthesizing organisms.  What would happen if the Earth had only half as many photosynthesizing organisms?  Construct your predictions as a short essay.

The Process

First, visit the websites to gain any insights that you can in relatin to input and outputs then construct your essay and provide a defense of your predictions (the predictions don't have to be correct, just well defended).

To construct your essay try looking at photosynthesis in terms of input and output and then imagine it on a massive, global scale.

This is where you list a few web sites, include some images, and ask some very specific questions students are supposed to answer by visiting the sites.


Describe to the learners how their performance will be evaluated. Specify whether there will be a common grade for group work vs. individual grades.












Stated Objective or Performance


Discussion does not include key elements of photosyntesis
Key elememts identified but not placed in a logical sequence.
Identify key elements in a logical sequence of reactions and how they relate to the Earth
Identify key elements in a logical sequence of reactions and how they relate to the Earth and relate to the geological record.



Hopefully this exercise has given you the oportunity to consider  how some of the most simple and common biological processes  can have consequences on the geological and global scale.

Credits & References

Intro image from:,r:7,s:0

Last updated on May 9, 2010.