Cells: Division (DP IB Biology: SL)

The photomicrograph shows cells in different stages of mitosis.

In which order do these stages occur?

Which of the following does not happen in an animal cell cycle?

1. DNA is transcribed and translated.
2. Spindle is formed from microtubules.
3. Cell plate forms to divide daughter cells
4. Plasma membrane pulled inwards around cell equator to form cleavage furrow

Tumors are formed from uncontrolled cell division of cancer cells.

Which statement describes the difference between a normal cell and a cancer cell?

The cell cycle is shown in the diagram below.

If dividing cells are supplied with radioactive nucleotides, at which point will the nucleotides be incorporated into the chromosomes?

What properties does a human cell have just before it enters prophase?

	Nuclear membrane present	Spindle present	Number of chromatids
A	No	Yes	92
B	Yes	No	92
C	Yes	Yes	46
D	Yes	No	46

The graph shows the survival probabilities for current smokers and for those who never smoked among men 20 to 70 years of age.

What can be concluded from this graph?

Each of the following events takes place during mitosis.

1	Chromosomes uncoil.
2	Chromatids move to opposite poles of the cell.
3	Centromeres divide.
4	Chromosomes line up along the equator of the spindle.
5	Two chromatids are joined by a centromere.

In which order do the events take place?

	First     →→→→→→→→→→→→→→→→→     Last
A	1	2	4	5	3
B	3	1	2	4	5
C	4	5	3	1	2
D	5	4	3	2	1

The table below shows the number of cells in different stages of mitosis in a sample from a garlic root tip.

Stage of mitotic cell cycle	Number of cells
Interphase	80
Prophase	11
Metaphase	2
Anaphase	4
Telophase	3

What is the mitotic index for this tissue?

The risk of developing a cancerous tumour is increased by exposure to which of the following?

	Ultraviolet light	Viruses	Carbon monoxide	X-rays
A	✓	✓	✗	✓
B	✓	✗	✗	✓
C	✗	✓	✓	✗
D	✓	✗	✓	✗

         

                        Key: ✓ = increases risk, ✗ = does not increase risk

The diagram shows the chromosomes of a squashed cell during mitosis.

Which stage of mitosis is the cell in and what is the haploid chromosome number of this species?

	Stage of mitosis	Haploid chromosome number
A	Early prophase	5
B	Late prophase	5
C	Metaphase	10
D	Anaphase	10

The graph shows some mice cells undergoing DNA replication.

Some cells contain a protein called cyclin D which stimulates the activation of DNA polymerase.

Which of the following statements applies to the action of cyclin D?

The table shows the number of chromosomes and the mass of DNA in different nuclei of a human body cell.

Which row in the table correctly identifies the number of chromosomes and mass of DNA found in the nucleus during the named stage of the cell cycle?

An androgen receptor (AR) found in the cytoplasm of cells interacts with the sex hormone testosterone. 

A repeating nucleotide base sequence, CAG, found in the gene for AR has been associated with the risk of developing prostate cancer.

The table below shows the results of two statistical tests which found an association between the number of CAG repeats and the risk of developing prostate cancer.

Number of CAG repeats in AR gene	Association is significant at this probability level
≤ 10	0.02
≥ 20	0.25

A null hypothesis stated that:

'There is no significant association between the number of CAG repeats and the risk of developing prostate cancer'

Identify the conclusion which can be drawn from the data in the table.

In humans, cell division is regulated by several genes, one of which, p53, inhibits cell division at a particular checkpoint in the cell cycle through the following mechanism.

• p53 stimulates transcription of a gene to produce protein X
• Protein X combines with a cyclin-dependent kinase (CDK) protein
• The complex prevents the initiation of mitosis

A heritable mutation in the p53 gene produces a dominant allele which inhibits the normal function of p53.

Which of the following explains the potential result of inheriting a mutant version of the p53 gene.

Some scientists were investigating mitosis in plant cells.  They applied a chemical agent called colchicine, which interferes with tubulin proteins in the cytoplasm. An image of some chromosomes from a treated cell can be seen below.

How does treatment with colchicine prevent the progression of cell division in plant cells?