Neco 2020 Biology Question 2

A biology student is investigating the stages of mitosis in an onion (Allium cepa) root tip. Fresh root tips are harvested, fixed in Carnoy’s solution, stained with aceto‑orcein and squashed on a slide. The student examines the slide under a microscope and records the number of cells in each phase of mitosis as shown in Table 1.\n\nTable 1 – Untreated root tip (total cells examined = 500)\nProphase: 120 cells\nMetaphase: 80 cells\nAnaphase: 50 cells\nTelophase: 30 cells\nInterphase: 220 cells\n\nThe same procedure is repeated after the seedlings have been treated with 0.1\% colchicine for 4 hours. The counts obtained are shown in Table 2.\n\nTable 2 – Colchicine‑treated root tip (total cells examined = 400)\nProphase: 100 cells\nMetaphase: 200 cells\nAnaphase: 50 cells\nTelophase: 30 cells\nInterphase: 20 cells