Igcse Model Questions Vol1 2021 Biology Question 2

Practice practical question 2 from the 2021 Igcse Model Questions Vol1 Biology examination. This question covers Cell Division .

Igcse Model Questions Vol1 2021 Biology Practical
Topic: Cell Division
Question 2 IGCSE_MODEL_QUESTIONS_VOL1 • 2021 • BIOLOGY • practical

A student prepares a fresh root‑tip squash of an onion and observes it under a microscope using a 40× objective and a 10× ocular lens. From a random field containing 120 cells the student records the following numbers of cells in each stage of mitosis:

Question Parts

( a )
Calculate the percentage of cells observed in each stage of mitosis (prophase, metaphase, anaphase, telophase) and the percentage of cells in interphase.
( b )
The observation is repeated on three different fields giving the following percentages of cells in mitosis (i.e. the sum of the four mitotic stages): 45 %, 48 % and 42 %. Calculate the mean percentage of cells in mitosis and the standard deviation (to one decimal place). Use the sample standard deviation formula.
( c )
Based on the results, discuss what the proportion of cells in mitosis indicates about the growth activity of the onion root tip.
( d )
Identify one procedural error that could lead to an over‑estimation of the mitotic index and suggest how to avoid it.

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About This Question

This is Igcse Model Questions Vol1 2021 Biology Question 2. It is one of the practical questions from the 2021 Igcse Model Questions Vol1 Biology examination.

The question covers Cell Division .

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