Class XI Practical: Cytology - Stages of Mitosis in Onion Root Tips

Objective

To prepare a temporary squash mount of onion root tips and observe different stages of mitosis.

Guidelines

1. Root Tip Preparation: Obtain actively growing onion root tips. Fix them in an appropriate fixative (e.g., Carnoy's fluid) and then hydrolyze them in HCl.
2. Staining: Stain the root tips with acetocarmine or aceto-orcein stain.
3. Squashing: Place a stained root tip on a slide, add a drop of water, and gently squash it under a coverslip using the thumb, ensuring cells are spread in a single layer.
4. Observation: Observe the slide under a compound microscope. Systematically scan for cells undergoing different stages of mitosis: prophase, metaphase, anaphase, and telophase.
5. Drawing: Draw neat, labeled diagrams of each identified mitotic stage.

Expected Outcome

Identification and differentiation of the various stages of cell division (mitosis) in plant cells.