ASEI Lesson Plan on Biology

Lesson Note on Transport in Plants

Subject: Biology

Theme: Transport in Plants

Topic: Transport in Plant II

Sub Topic: Internal Structure of a Dicotyledonous Stem

Date: dd/mm/yyyy

Class: S.S.S 2

Duration: 35 Minutes

No of Learners: 30

Learning Objectives:

By the end of the lesson learners should be able to:
  1. Identify and draw the internal tissues of dicotyledonous stem under a light microscope.


  2. Identify the plant tissue that is involved in the transportation of water and mineral salts in dicotyledonous stem using a light microscope.

  3. The part that transports water and mineral salts are;

    • Vascular bundle
  4. Compare the internal structure of a stem of monocotyledonous and dicotyledonous plants

  5. Vascular bundles in dicotyledonous plants are arranged like a ring while those in monocotyledonous are scattered

Rationale:

The stem is a plant organ whose primary functions are to support the shoot, conduct water and mineral salts from the roots to the leaves and transfer manufactured food from the leaves to the other parts of the plants. Various tissues in the stem carry out these functions. Knowledge of this will make learners appreciate that the internal structures of monocotyledonous and dicotyledonous stems differ in a relation to the arrangement of their tissues.

Prerequisite/ Previous knowledge:

  • Use of a light microscope
  • Cell specialisation (Cells, tissues, organs)
  • Preparation of temporary slides
  • The internal structure of the monocotyledonous stem.

Learning Materials:

Light microscopes, scalpels, slides and cover slips, young dicotyledonous plant e.g. Bidens pilosa L. (Asteraceae) 'the black jack' and monocotyledonous plant, Petri dishes, water, eosin solution and a chart of the internal structures of stems, photomicrograph of a dicotyledonous stem, white tiles

Reference Materials:

Biology A New Approach For Senior Secondary Schools and Colleges By E. O. Egho,
Modern Biology for SSS By Kucy I. Aunwa et-al



Lesson Development:

STAGE
TEACHER'S ACTIVITY
LEARNER'S ACTIVITY
LEARNING POINTS
INTRODUCTION
full class session (5mins)
The teacher provides Learners with 2 plants in flasks labelled A and B dipped in eosin dye, and ask learners:
  1. to identify the two major groups the plants' A and B belong to.
  2. List down the external observation that helped you to classify the two plants.
  3. Looking at the chart showing the internal structure of the monocotyledonous stem, predict which of the labelled parts would be stained red with the dye. Give your explanation for the answer you have given.

    The teacher draws a table and list down the differences.

Learners observe the two plants and identify the groups the plant belongs to.

  1. Plant A: monocotyledonous plant,
  2. Plant B: dicotyledonous plant.
Learners account for their classification by listing down the differences between the two plants (Minds-on activity).
The external differences between them are:
  1. Monocotyledonous plants have parallel venation while dicotyledonous have network venation.
  2. Monocotyledonous plants have narrow leaves while dicotyledonous have broad leaves.
  3. Monocotyledonous plants have fibrous roots while dicotyledonous plants have a tap root system.

Observation and identification of plants
The teacher asks learners the following questions;
  1. Which of the part labelled would have stained red with the dye? And why?
  2. What is the part that transports water and mineral salts
  3. Identify the two types of tissues in V/bundle

Learners observe the two plants and notice what has happened to the red dye.

Learners look at the chart of a plan diagram of the internal structure of the monocotyledonous stem.

  1. The red dye has moved through the root, stem to the leaves.
  2. The vascular bundle is the part that transports water and mineral salts.
  3. the two types of tissues in V/bundle are Xylem and phloem.

Development
(20 minutes)
Activity 2 (Sectioning):

The teacher provides material, apparatus and students worksheets.
The teacher gives brief instruction and necessary CAUTION.

Teacher guide learners to perform the following activity;

  1. Cut a slit in a potato tuber.
  2. Insert a piece of the stem of the dicotyledonous plant between the potatoes slit, for firm holding of the stem.
  3. Cut suitable thin transverse sections through a dicotyledonous stem.
  4. Keep the sections in water in a Petri dish.
  5. Select the thinnest section from the Petri dish, mount on the slide, and place a coverslip.
  6. Examine the section under the microscope (low power objective, then medium power objective).
  7. Draw a large labelled plan diagram of the section.


Teachers supervise and guides students.

The learners form working groups.


The learners cut and mount transverse sections of the stem (Hand-on activity).

Learners observe sections under the light microscope.

CAUTION: about handling sharp cutting instruments (scalpel).
Sectioning and manipulation of the microscope.

For the vascular bundle of the stem to be seen learners must cut the transverse section.

The specimen should be very thin to pass through light.

(Drawing and labelling)
Learners draw a plan diagram of what they observe and they label the diagram as they discuss (Minds-on activity).
Learners answer the following questions.
  1. - In which tissue are the cells coloured red?
  2. How do you explain this?
Recording observation by drawing

Reasoning and clarification
  1. Xylem is the part that is coloured red.
  2. Dye dissolved in water and moved through the stem.
EVALUATIONbr (10 minutes) The teacher evaluates the lesson by posing questions;
  1. generalize the internal structure of a stem of a dicotyledonous plant using a chart.
  2. compare the monocotyledonous and dicotyledonous internal structures of the stem.
  1. Major plant tissues to be identified include vascular tissue (xylem and phloem), cortex, cambium and epidermis).
  2. Organising the concepts through comparison and contrast
    Vascular bundles in dicotyledonous plants are arranged like a ring while those in monocotyledonous are scattered
Asking the learners questions to assess the achievement of the set objectives.
CONCLUSION
5mins
The teacher consolidates the main points and corrects any misconceptions. Learners consolidate the key areas of drawing and labelling plan diagrams. The main points are no shading, continuous lines, use of sharp pencil and to draw what is observed.
ASSIGNMENT
  1. Give a comparison between the internal structure of a monocotyledonous and a dicotyledonous stem.
  2. Give a reason why each of the following steps is followed:
    1. Cutting very thin sections
    2. Using a sharp razor blade during the cutting
    3. Placing the sections in water
    4. Staining the sections before observing under the microscope
Learners answer other questions Improving their level of understanding