Question

Plants produce oxygen and animals and humans use oxygen. About 21 percent of Earth’s atmosphere is oxygen, enough for all living creatures. For many years, plants and animals have kept a bargain. Animals breathe the oxygen produced by plants. At the same time, plants use the carbon dioxide that animals exhale. They mix it with water and sunlight to produce a sugar called glucose. As it turns out, glucose is the basic energy source for both plants and animals. The waste produced by this process is oxygen. The bargain between plants and animals has been in the right balance for many millions of years. If we humans are smart enough not to upset that balance too much, all life on Earth will benefit from it for millions of years to come.

Plants are able to use water, carbon dioxide, and sunlight to produce glucose plus oxygen. What's the effect of this for animals?

What might be a cause that would break the bargain between plants and animals?

Answer 1

A good answer should contain the following:

Animals need the oxygen to breathe, and glucose is the basic energy source for animals.

If humans or animals destroy too many plants, there may not be enough oxygen for animals.

Step-by-step explanation:

Answer 2

I don't know if I would call it a bargain. Ocean phytoplankton, produce 50 to 85% of the world's Oxygen as a by product of photosynthesis. With trees and shrubs producing the other half. This is where the food chain begins. These plants covert the light of the sun into engery we all use in the form of sugars our animal bodies need for energy and life. Animals throughout the food chain including us really on those plants for food and oxygen. Human activity is the biggest danger to this. If humans continue to pollute the oceans by releasing carbon into the atmosphere the planet will warm and the oceans will become too acidic for these organisms to thrive. Between desertification, deforestation, and pollution there might not be much of a bargain left.