Igcse Model Questions Vol1 2020 Biology Question 2

Practice practical question 2 from the 2020 Igcse Model Questions Vol1 Biology examination. This question covers Cell Division .

Igcse Model Questions Vol1 2020 Biology Practical
Topic: Cell Division
Question 2 IGCSE_MODEL_QUESTIONS_VOL1 • 2020 • BIOLOGY • practical

A student investigates mitosis in the root tip of an onion (Allium cepa). The root tip is harvested, fixed in 1 % acetic acid, stained with Feulgen stain, and a squash preparation is made for observation under a light microscope.

Question Parts

( a )
Outline the steps required to obtain a suitable squash preparation for observing mitosis in the onion root tip.
( b )
In the prepared slide the student examines 10 randomly selected fields and records the number of cells observed and the number of cells in mitosis as follows: Field 1: 120 cells, 6 mitotic Field 2: 115 cells, 5 mitotic Field 3: 130 cells, 7 mitotic Field 4: 118 cells, 4 mitotic Field 5: 122 cells, 6 mitotic Field 6: 119 cells, 5 mitotic Field 7: 124 cells, 6 mitotic Field 8: 117 cells, 5 mitotic Field 9: 121 cells, 7 mitotic Field 10: 123 cells, 6 mitotic Calculate the mitotic index (percentage of cells in mitosis) for the whole slide. Show all calculations.
( c )
Explain what a high mitotic index indicates about the growth activity of the root tip and suggest one factor that could artificially increase the observed mitotic index.

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About This Question

This is Igcse Model Questions Vol1 2020 Biology Question 2. It is one of the practical questions from the 2020 Igcse Model Questions Vol1 Biology examination.

The question covers Cell Division .

View More Igcse Model Questions Vol1 2020 Biology Questions More Igcse Model Questions Vol1 Practice Questions Back to Questions

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