Introduction

How do the cells in the leaf support photosynthesis?


A10.1 Photosynthesis
The leaf is where the majority of photosynthesis takes place in plants. This means leaves have their own system with tissues and specialized cells that focus on the process of photosynthesis. Remember, photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose (a type of sugar used for energy) and oxygen. The chemical equation for this process is

«math» «msub» «mi»CO«/mi» «mn»2«/mn» «/msub» «mo»§#160;«/mo» «mfenced» «mi mathvariant=¨normal¨»g«/mi» «/mfenced» «mo»+«/mo» «msub» «mi mathvariant=¨normal¨»H«/mi» «mn»2«/mn» «/msub» «mi mathvariant=¨normal¨»O«/mi» «mo»§#160;«/mo» «mfenced» «mi mathvariant=¨normal¨»l«/mi» «/mfenced» «mo»+«/mo» «mi»Sunlight«/mi» «mo»§#8594;«/mo» «msub» «mi mathvariant=¨normal¨»C«/mi» «mn»6«/mn» «/msub» «msub» «mi mathvariant=¨normal¨»H«/mi» «mn»12«/mn» «/msub» «msub» «mi mathvariant=¨normal¨»O«/mi» «mn»6«/mn» «/msub» «mo»§#160;«/mo» «mfenced» «mi mathvariant=¨normal¨»s«/mi» «/mfenced» «mo»+«/mo» «msub» «mi mathvariant=¨normal¨»O«/mi» «mn»2«/mn» «/msub» «mo»§#160;«/mo» «mfenced» «mi mathvariant=¨normal¨»g«/mi» «/mfenced» «/math»

In this way, plants create their own food and do not need to eat to survive like animals do.

In this lesson, you will learn the different specialized tissues and cells needed for photosynthesis. You will also learn where they are located in the leaf and complete an activity around this.

  Did You Know?


A10.2 Fossil of a fern

Today, the air is made up of 78% nitrogen, 21% oxygen, and less than 1% carbon dioxide. When Earth was first formed, there was little to no oxygen on the planet, but as plants evolved, they took the carbon dioxide present and converted it into oxygen for other life forms to use.


  Targets

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

        • describe how the cells of the leaf system have a variety of specialized structures and functions
        • identify the structure and function of the epidermis, including guard cells, palisade tissue cells, spongy tissue cells, and phloem and xylem vascular tissue cells that support the process of photosynthesis

          Virtual Lab


        Photosynthesis Lab © Explore Learning
        Background Information:

        This lab gives you an idea of how much oxygen is produced through photosynthesis and the factors that affect production.

        1. Launch the Gizmo by clicking on the play button. Print students can access the Gizmo in the Online Resources for Print Students section of their online course.


        1. This part of the Gizmo allows you to play with the carbon dioxide present, temperature, and light intensity to see how those factors affect the production of oxygen. You can see the amount of oxygen produced by reading the measurements in the oxygen tube or looking at the oxygen flow reading.
        2. Change the three variables and see how they affect the oxygen output.
        3. Record the ideal «math» «msub» «mi»CO«/mi» «mn»2«/mn» «/msub» «/math», temperature, and light intensity you found. The ideal «math» «msub» «mi»CO«/mi» «mn»2«/mn» «/msub» «/math», temperature, and light intensity are the values of those variables that allow for the most amount of oxygen to be produced.

        ©Explore Learning
        A10.3 Where to read oxygen flow
        1. Switch to the “Color” tab.
        2. In this set up, you can see which colour of light and temperature produces the most oxygen. Move the carbon dioxide level up to 1000 ppm, and the light intensity to 100%

        ©Explore Learning
        A10.4 How to switch tabs
        1. Now move the light wavelength around until you find the colour of light that produces the most oxygen.
        2. Once you have found the light wavelength, move the temperature up and down until you find the temperature that produces the most oxygen.
        3. Please return to the top of this page and click on analysis to complete the analysis questions.


        1. What were the best conditions for photosynthesis with the white light?
        Having 81 to 88% intensity and 1000 ppm of carbon dioxide were the best conditions. This makes sure the plant has all the light and carbon dioxide needed to perform photosynthesis, ensuring these factors are not limiting that process. You will learn more about how plants are affected by light in this lesson.

        1. What was the ideal colour of light for photosynthesis?
        Blue light (or a wavelength of 450 nm) is the ideal light for photosynthesis.

        1. What was the ideal temperature for photosynthesis in the different coloured lights?
        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.