CP3 Squash root

Question 1

Where in plants can cell undergoing mitosis be found?

Answer 1

• Meristem tissue and roots + shoot.

Question 2

What is the mitotic index?

Answer 2

• Ratio of number of cells undergoing mitosis to total number of cells in a sample.

Question 3

Outline the procedure to prepare a root tip slide.

Answer 3

• Heat 1M HCl to 60°C.
• Cut root tip w/ scalpel + add to HCl for 5 mins.
• Remove from HCl + wash w cold distilled water.
• Dry + place on slide.
• Macerate w/ needle to spread cells.
• Add few drops of stain.

Question 4

Why is stain added?

Answer 4

• To make c’somes visible.

Question 5

What is the formula for mitotic index?

Answer 5

• Mitotic index = number of cells w/ visible c’somes / total number of cells.

Question 6

What are the hazards and precautions for reagents used in this experiment?

Answer 6

• HCl - Corrosive - avoid contact w/ skin + wear eye protection.
• Stain - irritant - avoid contact w/ skin + wear eye protection.
• Scalpel - cut away from fingers.

Question 7

Why is root tip placed in hot HCl?

Answer 7

• Dissolves middle lamella to break up cellulose wall.
• Allows stain to permeate + be squashed more easily.

Question 8

Why is sample squashed?

Answer 8

• To flatten + reduce number of layers.
• Reducing overlap - cell can be seen more easily.