Required Practicals

Question 1

RP1

Question 2

RP2: Calculating Mitotic Index in Plant Cells

Answer 2

-Mitotic Index = Number of cells undergoing mitosis / Total number of cells
-This ratio indicates the proportion of cells undergoing mitosis in a given sample.

Method
-Heat 1 mol dm⁻³ HCl to 60°C in a water bath.
-Cut a small segment of the root tip using a scalpel.
-Place the root tip in the heated HCl for 5 minutes to soften the tissue.
-Remove the root tip and wash it in cold distilled water.
-Place the tip on a microscope slide and add a few drops of toluidine blue stain to make chromosomes visible.
-Carefully lower a cover slip onto the slide, avoiding air bubbles.
-Place the slide under the microscope, starting with the lowest magnification.
-Use the coarse adjustment knob to bring the lens close to the slide, then the fine adjustment knob to focus the image.
-Identify and count cells in different stages of mitosis (prophase, metaphase, anaphase, telophase) and the total number of cells.
-Calculate the mitotic index.

Safety Considerations
-Hydrochloric Acid: Corrosive; wear eye protection and gloves. In case of contact, rinse immediately with cold water.
-Toluidine Blue Stain: Can cause irritation; handle with care and avoid contact with skin and eyes.
-Scalpel: Sharp instrument; cut away from the body and handle with caution.
-Glassware: Handle slides and cover slips carefully to prevent breakage and potential injury.

Question 3

RP3: Investigating Water Potential in Plant Tissue

Answer 3

Method Summary
-Prepare Dilution Series: Create sucrose solutions of varying concentrations (e.g., 0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1.0M) by diluting the 1 mol dm⁻³ stock solution with distilled water.
-Measure Solutions: Pour 5 cm³ of each sucrose solution into separate boiling tubes. 
-Prepare Potato Chips: Use a cork borer to cut uniform potato cylinders. Trim them to equal lengths using a scalpel and measure their initial masses after gently blotting to remove excess moisture. -Incubation: Place one potato chip into each boiling tube containing the different sucrose solutions. Leave them for a set period (e.g., 20 minutes). 
-Post-Incubation: Remove the potato chips, gently blot to remove surface solution, and measure their final masses.
-Calculate Percentage Change: For each chip, calculate the percentage change in mass using the formula: Percentage Change = (Final Mass -Initial Mass / Initial Mass) X 100

Data Analysis
-Plotting Results: Create a graph of percentage change in mass against sucrose concentration.
-Determining Water Potential: The point where the line crosses the x-axis (zero percentage change) indicates the sucrose concentration that is isotonic to the potato tissue. This concentration corresponds to the water potential of the potato cells.

Safety Considerations
-Scalpel Usage: Handle with care to avoid cuts. Always cut away from the body and use a cutting mat.
-Glassware: Handle boiling tubes carefully to prevent breakage and potential injury.

Question 4

RP4: