Biology
     
                                       
     

Biology

Plant Tissues

            
                             
     

           
                           
                                       
               
Plant Tissues:
groups of cells that perform a common function.
          
                                       
 

• Ground Tissues - provides storage, metabolism, and support.

Parenchyma

• Large, loosely packed, rectangular cells with thin cell walls.
• Responsible for photosynthesis and food storage.
• Over 80 % of the cells in non-woody plants.

Collenchyma

• Elongated cells with uneven, flexible cell walls.
• This tissue supports the growth regions of a plant.

Sclerenchyma

• Cells are short-lived with thick cell walls.
• Serves to support the plant.
• The cells that give a plant its "woody" characteristics.

  
                       
                                       
  • Dermal Tissues - forms the outside covering of plants and provides protection.
                                       
           

Epidermis

• The outer layer of cells.
• Protects the plant and reduces water loss.

Stomata

• Regulate gases passing into and out of the plant
• Usually located on the under side of leaves.
• Guard cells regulate the opening by changing water pressure within the cell to swell or shrink.

Cork: closely packed cells protecting a woody stem.

        
             
                   
                                       
   

Vascular Tissues - transport water and food through the plant.

Phloem: straw-like tubes conducting food downward in a plant.

Xylem: straw-like tubes conducting water and minerals upward in a plant.

To remember which of these tissues does what, think of this:

Glucose is produced by leaves - high on the plant - and "flows" (like phloem) downward.


        
                     
                                       
      Water is moved to the tops of very tall trees by capillary action, the adhesion/cohesion of water, transpirational pull, and root pressure.                    
 
The Process That Produces Transpiration Pull:
 

The largest force (transpirational pull) results from the evaporation of water from the leaves at the top of the tree. A tree behaves like a big straw, as water moves out of the leaves at the top and water moves in at the roots to replace it.
Capillary action (what holds the water together) is a consequence of the high surface tension of water due to hydrogen bonding.
Theoretically this process could continue at a very great height, but in practical terms trees are restricted to a maximum of about 400 feet (California redwoods) because of the requirements of stability. Water has been measured traveling up the stems of some oak trees at a rate of 60 meters per hour.
 
   
                                       

EOI Question # 50

Turgor is the internal cytoplasmic pressure that results from the amount of water absorbed by plant cells. The pictures above show a turgor pressure demonstration using stalks of celery in different salt solutions. Which of these shows the celery stalks in order from the one with the most turgor pressure to the one with the least turgor pressure?


Each of these celery stalks has been in its solution the same length of time. What can you tell about each of the solutions?

 
   

A. Q, T, S, R
B. R, S, T, Q
C. S, R, T, Q
D. T, Q, R, S

 
       

 

• Meristems: growth regions where cells divide rapidly and tissue differentiation occurs.

Apical meristem - located at the tips of stems and roots.

Apical meristems produce growth in length, primary growth.

Lateral meristem - located around the edge of stems and roots.

    

Lateral meristems produce growth in circumference, secondary growth.

Two types of lateral meristems:

1. Vascular cambium - located between the xylem and phloem, producing additional vascular tissues.
2. Cork cambium - located outside the phloem, producing cork.
                             
 

 

Create a Power Point as instructed. Use the photos provided. Have this assignment done before class tomorrow.

Create a title slide with yor name, hour and class on it.
1. Paste this picture onto a PowerPoint slide with this layout.

• Title the slide "Ground Tissues".

• On the text side of the slide, use three or four words to tell what each type of tissue does for the plant.

2. Paste this picture onto a new slide with the same layout.

• Title the slide "Guard Cells".
• Label the guard cells in the top half of the picture.
• On the text side of the slide, briefly describe how the cells are able to change shape to open or close the stoma.

3. Paste this picture onto a new slide with the same layout.

• Title the slide "Vascular Tissues".
• On the text side of the slide, briefly describe the function of each tissue.

Save this set of slides and show them to your science facilitator.
Your next assignment will add to these slides.

 

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