Theory:

Activity - cut section of the stem:
  1. Take a plant stem and cut into very thin slices or sections with the help of your teacher.
  2. Stain the slices with safranin and place one neatly cut section on a slide and put a drop of glycerine.
  3. Cover the slide with a cover slip and observe the cut section under the microscope. Carefully, observe the different types of cells and the arrangement of the cells.
Figure_30_01_02f.jpg
Cross section of a stem
 
Answer the following based on your observation.
  1. Are all cells similar in structure?
  2. How many types of cells are seen through the microscope?
  3. Why there are so many types of cells? Can we think of reasons?
We can also try to cut plant roots' sections. We can even try cutting sections of roots and stem of different plants.
 
Ranunculus_Root_Cross_Section.png 
Cross section of a root
 
Answers:
  1. No, the cells are not similar in structure.
  2. Different types of cells that can be seen in the cut section of the stem are;
    a) Epidermis
    b) Phloem vessels
    cCambium
    d) Cork
    e) Pith
    f) Xylem vessels
  3. The presence of different types of cells in the stem is due to the various functional requirements of the plant for their survival. Each cell has its own specific function.
diagramshowinginternalstemstructure130834117.jpg
Internal structure of a stem
Important!
a) Epidermis: Outer protective layer of the stem.
b) Phloem vessels: Tubes that carry food and water.
c) Cambium: Responsible for secondary growth of stems and roots.
d) Cork: Protective covering of the stem.
e) Pith: Store and transport nutrients throughout the plant.
f) Xylem vessels: Vessels that carry water.
Reference:
https://www.freepik.com/free-vector/diagram-showing-internal-stem-structure_5837811.htm
https://upload.wikimedia.org/wikipedia/commons/b/b1/Plant_stem_%28255_06%29_Cross-section_of_stem_of_Aristolochia.jpg
https://upload.wikimedia.org/wikipedia/commons/9/9e/Ranunculus_Root_Cross_Section.png