Introduction

Plants, just like animals, exchange gases. They exchange oxygen for carbon dioxide.


A11.1 The mitochondria is the location of cellular respiration.
All plant cells undergo cellular respiration, just like animal cells. This is the process where glucose and oxygen are used to create energy, carbon dioxide, and water. It is essentially the opposite process to photosynthesis. The chemical equation for cellular respiration is

C6H12O6 s+O2 g→CO2 g+H2O l+energy

This process is used to create the energy the cells need to perform the basic life functions. To review what cells use energy for, reread Lesson 4 on the parts of the cell and Lesson 6 on the cell membrane.

Plants create all the glucose they need through photosynthesis and, depending on the amount of sunlight available, produce all the oxygen they need as well. In fact, they often produce more oxygen than is needed and release the extra into their environment. This means while plants use oxygen and undergo gas exchange just like animals, they tend to do it backward. They take in carbon dioxide and release oxygen.

By the end of this lesson, you will understand how a plant exchanges gases.

  Targets

By the end of this lesson, you will be able to

  • explain the gas exchange system in plants and how diffusion is used in this system
  • identify the structure and function of the lenticels, guard cells, and stomata

  Interactive Activity


Cell Energy Cycle © Explore Learning


Background Information:

This activity gives a great visual for how photosynthesis and cellular respiration are complementary processes. It will help you understand what reactants are needed for each process.

Please note: if you scroll down while in the Gizmo you will see a list of questions. You DO NOT need to complete these questions. You are able to complete them for extra practice if you would like.

  1. Launch the Gizmo by clicking on the play button.
  2. Check off “Show formula of chemical equation” at the bottom of your screen.
  3. This will take you to the “Photosynthesis” tab. In this tab, you need to drag the two chemicals needed for photosynthesis into the chloroplast.
  4. Once you have dragged the chemicals needed over, add light by clicking on the “Add light” button.
  5. This will show you the chemicals photosynthesis creates.
  1. Click on the “Respiration” tab.
  2. Check off “Show formula of chemical equation” at the bottom of your screen.

©Explore Learning
A11.2 How to switch tabs
  1. In this tab, you need to drag the two chemicals needed for cellular respiration into the mitochondrion.
  2. Once you have dragged the chemicals needed into the mitochondrion, click the “Next” button in the top right-hand corner.
  3. Read the explanations in the bottom left corner of your screen and keep clicking the “Next” button to see the process of cellular respiration.
  4. Click on the “Cycle” tab.
  5. Drag the chemicals to the processes they are needed for. The animation will move the chemicals in place for you to show how these two processes create a cycle.
  6. Please return to the top of this page and click on analysis to complete the analysis questions.
  1. Explain why cellular respiration and photosynthesis are complementary processes.
They are complimentary processes because the products of one are the reactants of the other. This means photosynthesis produces the chemicals needed for cellular respiration and cellular respiration produces the chemicals needed for photosynthesis.

  1. What gases are exchanged when an animal breathes? What gases do plants exchange when they perform photosynthesis?
The lungs of animals breathe in oxygen and breathe out carbon dioxide because the cells in an animal body perform only cellular respiration. A plant will release oxygen and absorb carbon dioxide. We will look at how plants exchange these gases in this lesson.
Around 23 to 25 degrees Celsius was the best temperature no matter what light colour was used. You will learn more about how temperature affects photosynthesis in this lesson.