Neco 2022 Biology Question 2

Practice practical question 2 from the 2022 Neco Biology examination. This question covers Cell Division .

Neco 2022 Biology Practical

Topic: Cell Division

Question 2 NECO • 2022 • BIOLOGY • practical

A biology student investigates the effect of a growth regulator (GA3) on the mitotic activity in onion (Allium cepa) root tip cells. Two sets of root tips are prepared: a control (no treatment) and a treated set soaked in 0.5 mg/L GA3 for 24 h. For each set, a squash preparation is made and 5 fields are examined under a microscope. The following counts are obtained: Control: total cells counted = 500; cells in prophase = 45; metaphase = 30; anaphase = 20; telophase = 15. Treated: total cells counted = 480; cells in prophase = 30; metaphase = 50; anaphase = 25; telophase = 20.

( a )

Calculate the mitotic index (MI) for each set, expressed as a percentage to one decimal place.

( b )

Determine the percentage increase or decrease in MI of the treated set relative to the control.

( c )

Based on the changes in the distribution of cells among the phases, infer which phase is most affected by GA3 and provide a brief explanation.

( d )

Suggest one precaution the student should observe when preparing the squash to avoid artefacts that could affect the counts.

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This is Neco 2022 Biology Question 2. It is one of the practical questions from the 2022 Neco Biology examination.

The question covers Cell Division .

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