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Biology class 9 lab practical, Lecture notes of Biology

Biology

This is used for class 9 practical. All the best!

Typology: Lecture notes

2025/2026

Uploaded on 02/17/2026

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NATIONAL PUBLIC SCHOOL- ITPL - BENGALURU
GRADE IX – BIOLOGY – PRACTICAL EXPERIMENTS
Experiment 1
AIM
To prepare stained temporary mount of onion peel cells and to record observations and draw labelled diagrams.
MATERIALS REQUIRED
Onion, plain slides, coverslip, watch glass, needles, forceps, brush, blade, safranin, blotting paper, glycerin and compound
microscope.
THEORY
Onion is a multicellular plant. Like other plant cells, the cell of onion peel consists of a cell wall, cell membrane,
cytoplasm, a large vacuole and a nucleus. The nucleus lies at the periphery of cytoplasm and vacuole is located in the
center. Presence of large vacuoles and cell wall confirms that cells of onion peel are plant cells.
PROCEDURE
1. Take a piece of onion and bend it to remove the transparent membranous structure called onionepidermal peel.With
help of forceps remove the peel from its inner side.
2. Place the peel in water in a watch glass.
3. Add a few drops of stain safranin, to the watch glass containing the peel for staining.
4. Now, wash the leaf peel with water and transfer it on to a clean slide with the help of brush.
5. Remove extra water from the slide surrounding the peel with the help of blotting paper.
6. To this slide, add a drop of glycerin over the peel and place the coverslip in a manner to avoid entry of air bubbles.
7. Soak away the extra glycerin with blotting paper.
8. Examine slide under the microscope.
OBSERVATIONS
1. A large number of rectangular cells with distinct cell wall can be observed.
2. Cytoplasm is seen as thin layer of deep coloured substance on inner surface of cell wall.
3. A big central vacuole is present in the cell.
4. A deeply stained round body called nucleus is seen in each cell.
RESULT
1. The epidermal peel of onion comprises of rectangular shaped cells. Each cell comprises of a nucleus, a central vacuole,
thin layer of cytoplasm and cell wall.
2. As cell walls and large prominent vacuole are present in each cell, the cells placed under observation are plant cells.
PRECAUTIONS
1. Always take a clean slide and hold it by its edges to avoid making the slide dirty.
2. Peel should be properly stain. Avoid under-staining or excessive staining of the peel.
3. Always transfer the peel with the help of brush.
4. Mounting of the peel should be done in centre of slide.
5. Avoid folding of the leaf peel.
6. Remove extra glycerin with the help of blotting paper.
7. Avoid entry of air bubbles while placing the cover slip.
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NATIONAL PUBLIC SCHOOL- ITPL - BENGALURU

GRADE IX – BIOLOGY – PRACTICAL EXPERIMENTS

Experiment 1

AIM

To prepare stained temporary mount of onion peel cells and to record observations and draw labelled diagrams. MATERIALS REQUIRED Onion, plain slides, coverslip, watch glass, needles, forceps, brush, blade, safranin, blotting paper, glycerin and compound microscope. THEORY Onion is a multicellular plant. Like other plant cells, the cell of onion peel consists of a cell wall, cell membrane, cytoplasm, a large vacuole and a nucleus. The nucleus lies at the periphery of cytoplasm and vacuole is located in the center. Presence of large vacuoles and cell wall confirms that cells of onion peel are plant cells. PROCEDURE

  1. Take a piece of onion and bend it to remove the transparent membranous structure called onion epidermal peel. With help of forceps remove the peel from its inner side.
  2. Place the peel in water in a watch glass.
  3. Add a few drops of stain safranin, to the watch glass containing the peel for staining.
  4. Now, wash the leaf peel with water and transfer it on to a clean slide with the help of brush.
  5. Remove extra water from the slide surrounding the peel with the help of blotting paper.
  6. To this slide, add a drop of glycerin over the peel and place the coverslip in a manner to avoid entry of air bubbles.
  7. Soak away the extra glycerin with blotting paper.
  8. Examine slide under the microscope. OBSERVATIONS
  9. A large number of rectangular cells with distinct cell wall can be observed.
  10. Cytoplasm is seen as thin layer of deep coloured substance on inner surface of cell wall.
  11. A big central vacuole is present in the cell.
  12. A deeply stained round body called nucleus is seen in each cell. RESULT
  13. The epidermal peel of onion comprises of rectangular shaped cells. Each cell comprises of a nucleus, a central vacuole, thin layer of cytoplasm and cell wall.
  14. As cell walls and large prominent vacuole are present in each cell, the cells placed under observation are plant cells. PRECAUTIONS
  15. Always take a clean slide and hold it by its edges to avoid making the slide dirty.
  16. Peel should be properly stain. Avoid under-staining or excessive staining of the peel.
  17. Always transfer the peel with the help of brush.
  18. Mounting of the peel should be done in centre of slide.
  19. Avoid folding of the leaf peel.
  20. Remove extra glycerin with the help of blotting paper.
  21. Avoid entry of air bubbles while placing the cover slip.

Experiment 2

AIM

To prepare stained temporary mount of human cheek cells and to record observations and draw labelled diagrams. MATERIALS REQUIRED Slide, coverslip, needle, blotting paper, tooth pick, methylene blue, watch glass, compound microscope. THEORY Animal cells lack cell wall and prominent vacuole. In these cells a semi-permeable membrane called cell membrane surrounds the cytoplasm. In comparison to plant cell, in animal cell cytoplasm is dense and occupies larger space. Vacuoles are absent or very small in size. In animal cells, the position of nucleus is usually central. Cheek cells are part of squamous epithelium. They are thin and flat cells. They found arranged like pavement tiles, i.e., arranged end to end forming a delicate lining. PROCEDURE

  1. Rinse your mouth to remove any food particles.
  2. With the help of the toothpick scrap the inner side of the cheek to get some epithelial cells.
  3. Place the scrapping’s in a drop of water over a clean slide.
  4. Spread the scrapping’s with the help of needle.
  5. Add a drop of methylene blue over the slide.
  6. Wait for 2 minutes and then remove the extra stain with blotting paper.
  7. Add a drop of glycerin on the slide.
  8. With the help of needle, gently place the coverslip over the slide to avoid entry of air bubbles.
  9. Observe the slide under the microscope. OBSERVATIONS
  10. Large number of flat polygonal cells with irregular boundaries attached edge to edge are seen.
  11. The cells have thin membrane called cell membrane which encloses jelly like substance called cytoplasm. RESULT Cells under observation do not have cell wall and large prominent vacuole. So, cells of specimen on the slide are animal cells. PRECAUTIONS

1. Scrap the cheek cells gently with help of clean toothpick to avoid injury.

2. Always rinse the mouth before scrapping the tissue so as to remove any food particles from mouth.

3. Place coverslip gently to avoid entry of air bubbles.

4. Remove extra glycerin with blotting paper.

5. Spread the scrapping’s so that cells are properly distributed.

II. Collenchyma:

  1. Collenchymatous cells are somewhat oval to elongated.
  2. Each cell possesses large central vacuole and peripheral cytoplasm with prominent nucleus.
  3. Thickenings are present at corners of cells. Thickening comprises of cellulose and pectin.
  4. Intercellular spaces are absent.
  5. Collenchymatous cells are commonly present below the epidermis in petiole, leaves and stems. Its
  6. Main function is to provide mechanical strength. III. Sclerenchyma:
  7. Cells of sclerenchyma tissue are dead with highly thickened walls.
  8. Thickenings consist of lignin.
  9. There are two types of sclerenchyma cells:  fibres which are elongated cells with tapering ends and  sclereids (also called stone cells), which are roughly isodiametric cells with narrow cavities.
  10. Sclerenchymatous cells have pits which act as connections with adjacent cells.
  11. The main function of sclerenchyma is to provide support and mechanical strength to the plant.

PRECAUTIONS

  1. Handle the microscope carefully.
  2. Always focus the slide first at low power (10x) and then at high power (40x).

Experiment 4

AIM

To identify striped muscle fibres and nerve cells in animals, from prepared slides and to draw their labelled diagrams. MATERIALS REQUIRED Prepared slides of non-striated, striated and cardiac muscle fibres and nerve cells, compound microscope. THEORY A tissue is a group of cells that are similar in structure, origin and function. PROCEDURE

  1. Clean the microscope and adjust the light in microscope.
  2. Place the prepared slide of tissue on the stage of microscope and focus first at low power and then at high power.
  3. Observe the structure of tissues and draw the diagram of tissues as seen under microscope. OBSERVATIONS I. Striated Muscles or Striped or Skeletal Muscles:
  4. Striated muscle cells are cylindrical, elongated and enclosed in a membrane called sarcolemma.
  5. These muscle cells are multinucleated.

4.A myelin sheath is present over the axon in some nerve fibres, these are called myelinated nerve fibre and when myelin sheath is absent these are called non-myelinated nerve fibres. 5.Myelin sheath is not continuous. There are gaps along the entire length. Each gap is called nodes of Ranvier.

  1. Nerve cells help in conduction of nerve impulse. PRECAUTIONS
  2. Handle the microscope carefully.

2. Always focus the slide first at low power and then at high power.

Experiment 5

AIM

To determine the mass percentage of water imbibed by raisins. MATERIALS REQUIRED A few raisins with stalk intact, blotting paper, weight box, physical balance, petri dish. THEORY Raisins are dehydrated grapes. These when kept in water swell up. This happens due to imbibition of water and endosmosis. Imbibition is the adsorption of water or any other liquid by the solid particles of a substance causing it to increase in volume without forming a solution. The solid particles which adsorb water or any other liquid are called imbibants. The liquid which is imbibed is called imbibate. The phenomenon of imbibition occurs due to presence of hydrophilic colloids. Proteins, starch and cellulose are some examples of hydrophilic substances. Different substances have different imbibing capacity. Proteins have very high imbibing capacity, starch has less imbibing capacity and cellulose is the weakest imbiber. Because of difference in imbibing capacities, proteinaceous pea seeds swell more on imbibition than starchy wheat seeds. PROCEDURE

  1. Select a few raisins with intact stalks and weigh them.
  2. Now place these raisins in petri dish filled with water and cover it.
  3. Keep the set-up undisturbed overnight.
  4. Take out the swollen raisins from the petri dish and place them on a dry blotting paper to soak away the extra water.
  5. Weigh the swollen raisins and note their weight.

OBSERVATIONS AND CALCULATIONS

  1. Weight of dry raisins taken = _X 1 g = __________
  2. Weight of swollen raisins = _X 2 g = __________
  3. Weight of water imbibed by raisins = (X 2 – X 1 )g = X g = __________
  4. Percentage of water imbibed by raisins = (X ÷ X 1 ) x 100 =………… % RESULT The percentage of water imbibed by raisins = ………...% PRECAUTIONS
  5. Raisins should be with intact stalks.
  6. Proper care should be taken while weighing is done.
  7. Sufficient water should be taken in petri dish for soaking raisins.
  8. Before taking final weight, raisins should be dried with blotting paper to remove excess water.