The Leaf is for Photosynthesis

The leaf is designed with photosynthesis in mind.



A10.13 Cross section of a plant leaf
The leaf is a photosynthesizing machine! The entire structure of the leaf is designed to catch as much sunlight as possible and to allow for the gases needed by photosynthesis to enter. Each type of cell in the leaf has a specific function to carry out in regards to photosynthesis. The tissues in the leaf that are made up of these cells have the specialized function of making food for the rest of the plant.

Plants, just like animals, still undergo cellular respiration, even while performing photosynthesis. In the next lesson, we will look at how cells are specialized to allow for gas exchange and cellular respiration to occur.

Scroll down to complete a virtual lab on plant structure.




 

  Digging Deeper

A10.14 Coca plant leaves

In ancient civilizations, including Indigenous cultures, the coca plant (famous as it produces cocaine) was used as an anesthetic. In South America, the Incans were using the coca plant as a painkiller and in preparation for surgery long before western medicine started researching the plant in 1884. Go to the following link for more information on the uses of the coca plant. https://en.wikipedia.org/wiki/Coca#Traditional_uses

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Virtual Lab

Microscope Lab - Plant Structure and Function


Background Information:

Structures often look very different under a microscope than they do in diagrams. This virtual lab will give you practice identifying the structures we have talked about in a microscope setting. 

If you need a refresher on how to use the virtual microscope, please review Exercise 1 under Lab 1.  This microscope has an ocular lens magnification of 10x.

  1. Click on the play icon to open the virtual lab. Print students can access the Virtual Microscope in the Online Resources for Print Students section of their online course.
  2. Click on Exercise 3 under Lab 1
  3. Click on the procedures tab found on the right side of the screen.  This will open the procedures.  You will need to complete both procedures in this lab.
  4. Follow the directions found in the procedures. Remember, finding these tiny structures can take time. Some are very difficult to see, so try not to get frustrated! It is ok if you cannot find a structure or do not understand what you are seeing. Diagrams and real cells are very different things.
  5. Please return to the top of this activity and click on analysis to complete the analysis questions.
  1. Include the images or drawings you took of your cells in Procedure 1 in your notes to study from at a later date.  For more information on how to draw proper scientific diagrams, see page 481 in your textbook.


©Lord of Konrad, via Wikimedia Commons
Caption: A10.16 Leaf cross section with labels


  1. Include the images or drawings you took of your cells in Procedure 2 in your notes to study from at a later date.  For more information on how to draw proper scientific diagrams, see page 481 in your textbook.

  1. What is the total magnification used for the diagrams you created for each procedure?

In procedure 1 the total magnification used was 100x.  The ocular lens has a magnification of 10x and the 10x objective lens was used.
In procedure 2 the total magnification used was 400x.  The ocular lens has a magnification of 10x and the 40x objective lens was used.

  1. What was your estimated size of an open stomata?  How does that compare to the estimated size of one of the surrounding cells? Using the knowledge you have gained in this course, do those estimated sizes make sense according to the stomata's function?

The estimated size of the open stomata is 0.02 mm wide.  The estimated size of a surrounding epidermal cell is 0.1 mm wide.  This makes sense as the stomata needs to be wide enough to allow for transpiration and gas exchange, but cannot be too wide.  If it was too wide, too much water would escape through transpiration.  Different species of plants living in different conditions will have slightly different sizes of stomata as well.