Theory & Procedure, Characteristics of Dicot and Monocot Stem and Root | Additional Study Material for NEET PDF Download

Objective

Our objective is to prepare temporary stained glycerine mounts of transverse sections of the stem and root of Dicot and Monocot plants.

Theory

What is plant anatomy?

Stems and roots of plants are made up of different types of tissues. These tissues form different layers in the composition of stems and roots.  Plant anatomy is the general term for the study of the internal structure of plants.

To study the structural details of the stem or root of a monocot or dicot plant, it is essential to be familiarized with the sectioning and staining techniques used with plant materials.  It is also necessary to take the sections with uniform thickness so that the light passes through them equally and the different tissues found in the material are clearly visible under the microscope. To examine the tissues clearly, it is desirable to stain the section with suitable stains, as different stains colour the tissues differently.

Anatomy of Plant Stems and Roots

We will now look at the anatomy of dicot and monocot stems and roots.

Comparison of the Anatomy of Dicot  and Monocot Stems

Comparison of the Anatomy of Dicot and Monocot Roots

Points to Note

Conjoint:  Xylem and phloem occurs in same bundle.

Collateral: Phloem lies towards the outerside and xylem occurs towards the inner side.

Open: Cambium is present between phloem and xylem.

Closed: Cambium is absent between phloem and xylem.

Exarch: Protoxylem lies towards the outerside and metaxylem towards the centre.

Endarch: Metaxylem lies towards the outer side and protoxylem towards the inner side.

Learning Outcomes

• Students learn sectioning and staining techniques used with plant materials.
• Students learn about anatomy of monocot and dicot stems and roots.

Materials Required

Real Lab Procedure

• Take a blade and a sunflower stem to be sectioned.
• Dip the top of the material and the blade in water.
• Hold the material to be sectioned horizontally between the thump and the first finger of your left hand.
• Hold the blade in the right hand with the edge of the blade facing you and handle at right angles to it.
• Cut the sections of the material quickly using the blade.
• Transfer the sections in Petri dish containing water.
• Using a brush, select a thin uniform and complete section and place it on the glass slide.
• Using a dropper, take some safranin solution.
• Pour one drop of safranin solution over the section and allow it to stand for two minutes.
• Remove  excess stain using a filter paper.
• Pour a drop of glycerine over the section.
• Place a coverslip gently on the section with the aid of a needle.
• Remove the excess glycerine using a filter paper.
• Repeat the same procedure for the sunflower root, maize stem and maize root and prepare the slides.
• Observe each section under the microscope.

Simulator Procedure (as performed through Online Labs)

• To select a particular transverse section of stem or root sample, click on the corresponding icon.
• Click and drag the prepared slide of sample and place it on the stage of the compound microscope.
• Click on the eye piece of the compound microscope to view the transverse section of the sample.
• The power of the lens can be changed by selecting the required lens power from the drop down list ‘Select objective lens’.
• You can move the slide to observe each part of the sample by clicking on the directional arrow of the ‘Slide adjustment’.
• To repeat the experiment, click the ‘Reset’ button.

Precaution

• Dip the top of the material and blade in water before cutting the section.
• Brush should be used while handling the section.
• Remove extra glycerine with filter paper.