Name: ANSWERS
Mitosis Workbook
Year 12 Science
Ruawai College 2014
Mitosis is the process of cell division for growth and repair of cells.
Mitosis produces 2 ‘daughter’ cells that are exact replicas of the ‘parent’ cell.
The ‘daughter’ cells are genetically identical to the ‘parent’ cell.
All organisms start life as a single cell and growth occurs by cells dividing into two repeatedly.
1.
What is mitosis?
Cell division
2.
When does mitosis occur?
For growth or to repair cells
3.
How many ‘daughter’ cells are produced from one ‘parent’ cell?
2
4.
How many cells are produced after 3 divisions?
8
5.
Are daughter cells genetically identical to parent cells?
yes
6.
Why are all the cells in the diagram above genetically identical?
All originated from same cell
Before cell division can occur the DNA of each chromosome
must be copied.
7. What shape is a chromosome?
X shaped
8. How many chromatids are there in a chromosome?
2
9. What is the joining point of the chromatids called?
centromere
Cells go through a series of stages in a cycle and mitosis is one part of the cell cycle. Although mitosis
is a continuous process, certain stages have been recognised and given names.
10.
How many stages are in the cell cycle?
8
11.
How many stages are in the mitosis?
4
12.
What are the names of the stages in mitosis?
Prophase, metaphase, anaphase, telophase
13.
How many stages in interphase?
3
14.
What are the names of the stages in interphase?
G1, S, G2
15.
What is the name of the stage between mitosis and interphase?
Cytokinesis
DNA replication occurs prior to cell division during interphase (the time between cell divisions). A
cell spends about 90% of its time in interphase – the cell grows, carries out processes such as protein
synthesis and production of ATP, and gains nutrients needed for DNA replication and mitosis.
16.
Put the stages of the cell cycle in order starting with interphase:
Prophase
Anaphase
Telophase
Interphase – prophase – metaphase – anaphase – telophase
Interphase
Metaphase
17.
How much time does a cell spend in interphase?
90%
18.
When does DNA replication occur in the cell cycle?
Interphase
19.
What processes occur during interphase?
Protein synthesis, ATP production
20.
When does the cell grow?
During interphase
21.
When does the cell gain nutrients for DNA replication and mitosis?
During interphase
22.
Put arrows into the diagrams to show the order of the stages of mitosis.
Interphase stages
G1
S
First gap – cell is active with all its jobs
(synthesising proteins and enzymes) and the
organelles such as ribosomes begin to be
duplicated
DNA replication occurs
G2
Second gap – cell prepares for mitosis
23.
What is G1 the abbreviation for?
First gap
24.
What happens during G1?
Proteins and enzymes are made, organelles duplicated
25.
What happens during S?
DNA replication occurs
26.
What is G2 the abbreviation for?
Second gap
27.
What happens during G2?
Cell prepares for mitosis
28. What happens during prophase?
Chromosomes become visible
Nuclear membrane disappears
29. What happens during metaphase?
Chromosomes line up in centre of the
cell
30. What happens during anaphase?
Chromosomes separate – chromatids go
to ends of the cell
31. What happens during telophase?
Nuclear membrane reforms
During cytokinesis The cytoplasm divides
between the two nuclei so two new
‘daughter’ cells are formed.
28.
Complete the paragraph using the keywords below:
growth
biochemical
Cytokinesis
replication
chromosomes
microtubule
membrane
mitosis
mitosis
interphase
chromatids
centromere
interphase
chromatids
interphase
The cell cycle
The cell cycles between interphase and division / mitosis, spending approximately 90% of the time
in the interphase and approximately 10% of the time in mitosis . Interphase is the time of growth
and biochemical activities eg. synthesis of proteins, DNA and ATP. DNA replication occurs during
interphase. At the end of interphase, the chromosomes shorten and thicken and become visible as
two chromatids joined by a centromere. They line up at the centre of the cell and then the
chromatids are separated to each end of the cell by microtubule contraction. Nuclear membranes
form around each set of chromosomes. Cytokinesis occurs and the two new identical cells that have
formed enter interphase.
The rate of mitosis is rapid:
 in periods of growth
 following tissue damage
Some areas are more active in replacing wornout or damaged cells than others:
 dermis of the skin in humans
 bone marrow active in forming new red
blood cells
 in plants – root tips, stems, side
branches
 in plants – springtime, seedlings
The rate of mitosis can be influenced by
temperature, availability of nutrients, presence
of cancer-causing agents
29.
Outline the main events in the cell cycle.
Cells cycle between interphase and dividing .
90% of the time, cells are in interphase – utilising nutrients, carrying out essential processes such
as synthesis of proteins and enzymes.
DNA replication occurs late in interphase – allowing for chromosome replication.
Mitosis ensures each new cell gets a full set of chromosomes, so it can grow and carry out
processes during interphase that follows.
30.
Draw a series of labelled diagrams to describe mitosis.
31.
The rate of mitosis is not always the same.
Evaluate the statement above. In your answer, you should include:

factors that affect the rate of mitosis

stages in the life of an organism when the rate of mitosis is likely to be higher

locations in an organism where the rate of mitosis is likely to be higher
Identifies and describes factors affecting the rate of mitosis.
Eg, temperature, pH, presence of mutagens such as alcohol or radiation, availability of raw
materials in the cell.
Mitosis is usually higher during periods of growth and repair during infancy /childhood /early
development in animals following the breaking of dormancy, and during seasonal growth in
plants following damage to the organism when repair of tissue is necessary.
Mitosis occurs at a higher rate in areas where most growth or replacement of cells is
occurring, such as:
 root /shoot tips
 hair follicles
 bone marrow
 skin cells
 mucous membranes etc.
Mitosis rates increase in areas of cellular repair, the site of damage. Mitosis rates increase in
Cancer cells.