Mitosis IB style questions - model answers.

The diagram represents the cell cycle of a eukaryotic cell.  A single cell diving into two is also shown.
 

a        Identify the parts of the cell cycle labelled A and B.

A: …………… Interphase ……………….

B: …………… Mitosis …………………………………….                          (2)

b        State three activities that occur during phase A

DNA replication

Replication of organelles

Cell growth

……………………………………………………………………………………………………...     (3)

c        Outline what happens to a to the cells DNA in the steps labelled 3

The third step of mitosis - (Prophase, metaphase, anaphase, telophase) is anaphase

Chromosomes (double stranded) split into two single stranded chromosomes (previously chromatids)

Chromosomes (chromatids) are pulled to opposite ends of the spindle

……………………………………………………………………………………………………..      (2)

d        Mitosis produces two genetically identical cells, ie: each nucleus has exactly the same genes.
 Explain how the S-phase of interphase and Anaphase each help to make this happen.

S-phase of interphase is when DNA replication happens.

In this phase the single stranded chromosomes become double stranded, ready to separate at the beginning of anaphase

Each of the two DNA strands is identical

During Anaphase, all of the chromosomes split into two.

This ensures that a copy of each chromosome can go into each 'daughter' cell

Together the daughter nuclei have 'identical DNA in each chromosome' and 'an identical number of chromosomes'

……………………………………………………………………………………………………...     (2)

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