Question

how much time is spent in each phase of the cell cycle?
you will have slides of onion root tips where cells are undergoing mitosis. the slides are prepared by \fixing\ the cells and staining them. they are no longer dividing, but trapped in time.
to determine the amount of time the cell spends in each phase, you will count the number of cells that are in observed in each phase. the total time for the cell cycle in an onion cell is 720 minutes (12 hours). to calculate the amount, this formula can be used:
\\(\frac{\text{number of cells in a specific phase}}{\text{total number of cells counted}} \times 720 \text{ minutes} = \text{time for specific phase}\\)

1. this is an onion root tip at low power (100x). the cells are too small to distinguish individual phases. what phase do most of the cells appear to be in?
2. make a prediction about what phases will be longest and what phases will be shortest:

Explanation:

Question 6:

In the cell cycle, interphase (which includes G₁, S, and G₂ phases) is the longest phase as the cell grows, replicates DNA, and prepares for division. At low power, most cells in an onion root tip (where cells are in various cell cycle stages) appear to be in interphase because it occupies the majority of the cell cycle time. So the phase most cells appear to be in is Interphase.

Question 7:

The cell cycle has interphase (G₁, S, G₂) and mitotic phase (prophase, metaphase, anaphase, telophase). Interphase is longest because the cell spends time growing, replicating DNA, and preparing for division. The mitotic phase (M - phase) is shorter as it involves the actual division (chromosome separation, cell division). Among mitotic sub - phases, anaphase and telophase might be relatively shorter than prophase and metaphase, but overall interphase (G₁, S, G₂) is the longest, and the mitotic phase (especially sub - phases like anaphase/telophase) is the shortest. So a prediction could be: Interphase (including G₁, S, G₂) will be the longest phase(s), and the mitotic phase (or specific mitotic sub - phases like anaphase, telophase) will be the shortest phase(s).

Answer:

Question 6: Interphase

Question 7: Interphase (G₁, S, G₂) will be the longest; Mitotic phase (or its sub - phases like anaphase, telophase) will be the shortest.