Cell Division

Question 1

Why is mitosis important to organisms?

Answer 1

Allows organisms to grow and repair damaged tissue.

Question 2

Describe the structure of a chromosome.

Answer 2

A chromosome is made up of 2 sister chromatids joined at the centromere.

Question 3

Describe the stages of mitosis.

Answer 3

DNA found in the nucleus is copied in preparation for mitosis.
Chromosomes have become visible as pairs of identical chromatids joined at the centromere.
The nucleur membrane disintegrates, chromosomes become attached to spindle fibres and line up along the equatorial the cell.
The spindle fibres contract and pull the chromatids of each chromosome to opposite poles of the cell.
Nucleur membrane reforms around each group of chromosomes and the cytoplasm begins to divide.
Two identical daughter cells have been formed with the same number (diploid) of chromosomes as the original cell.

Question 4

What is chromosome complement?

Answer 4

All organisms have a specific chromosome complement.
Their diploid number.
Humans have 46 chromosomes
Mitosis ensures that daughter cells maintain the same number of chromosomes and have the same genetic information as the parent cell.

Question 5

Name 2 forms of growth media.

Answer 5

Pedro dish containing nutrient agar

Glass bottle containing nutrient broth

Question 6

What are aseptic techniques.

Answer 6

They are techniques that prevent contamination to an experiment.

Question 7

Name 5 precautions which must be taken to ensure aseptic conditions and explain why was he precaution must be taken.

Answer 7

Sterile petroleum dishes of nutrient agar are kept closed until required to prevent entry of contaminants.

Hands are washed before and after experiment to remove microbes.

Inoculated dishes are sealed with tape to prevent entry and exit of microbes.

Autoclave is used to sterilise glassware.

Lid held over Kerri dish inoculation to prevent entry of contaminants