Question

1. youre examining a thin section of onion root tip under a microscope. you record the number of cells that are in each stage of the cell cycle and observe the following: 94 cells in interphase, 14 cells in prophase, 3 cells in prometaphase, 3 cells in metaphase, 5 cells in anaphase, and 1 cell in telophase. (a) what is the proportion of cells at each stage? (b) if the complete cell cycle of the onion root tip requires 22 hours, what is the average duration of each stage in the cell cycle? assume that all cells are in the active cell cycle (5 pts).

Explanation:

Step1: Calculate total number of cells

$94 + 14+3 + 3+5 + 1=120$

Step2: Calculate proportion of cells at each stage

Interphase

Proportion = $\frac{94}{120}\approx0.783$

Prophase

Proportion = $\frac{14}{120}\approx0.117$

Prometaphase

Proportion = $\frac{3}{120}=0.025$

Metaphase

Proportion = $\frac{3}{120}=0.025$

Anaphase

Proportion = $\frac{5}{120}\approx0.042$

Telophase

Proportion = $\frac{1}{120}\approx0.008$

Step3: Calculate average duration of each stage

Interphase

Duration = $0.783\times22\approx17.23$ hours

Prophase

Duration = $0.117\times22\approx2.57$ hours

Prometaphase

Duration = $0.025\times22 = 0.55$ hours

Metaphase

Duration = $0.025\times22 = 0.55$ hours

Anaphase

Duration = $0.042\times22\approx0.92$ hours

Telophase

Duration = $0.008\times22\approx0.18$ hours

Answer:

(A) Interphase: 0.783, Prophase: 0.117, Prometaphase: 0.025, Metaphase: 0.025, Anaphase: 0.042, Telophase: 0.008
(B) Interphase: 17.23 hours, Prophase: 2.57 hours, Prometaphase: 0.55 hours, Metaphase: 0.55 hours, Anaphase: 0.92 hours, Telophase: 0.18 hours