Question

Reflection questions need to be answered using complete sentences. Some questions may require a longer explanation in paragraph form.
1. Based on your data, what can you infer about the length of time spent in each stage of the cell cycle?

2. What stages were the longest and shortest? Give a brief explanation of why these stages may have that time period.

3. What is a distinguishing visible feature of each stage of the cell cycle?

4. What differences can you see when you compare the nucleus of a dividing cell with that of a nondividing cell?

5 .If your observation had not been restricted to the tip of the onion root, how would the results be different?

Answer 1

1) Interphase is the longest phase and most of the cells are present in that very stage !!


2) Interphase is the longest phase and Anaphase is the shortest phase !! Interphase is the longest phase as in this phase the cells prepare themselves for dividing and it takes most of the time for gathering energy for division ; in this phase DNA also replicate !!


3)
Interphase: DNA replicates;

Prophase: Nuclear membrane starts disappearing and Centrioles go on opposite poles !! DNA condense to form Chromosome.

Metaphase: Chromosome attach to spindle fibre and starts to move to equitorial plate.

Anaphase: Centromere divide and half the chromatid goes on either pole

Telophase: Nuclear membrane starts to reassemble; Chrmosome goes to normal uncoiled state ; Other organelles starts appearing

Cytokinesis: Cell furrow forms and cell divides into two half.


4) In dividing cell nucleus membrane is absent while in non dividing cell the membrane is intact


5) Tip of the onion root is meristamatic cell which divides but if it is permanent cell ; there would be no division !!