Mitosis & Meiosis (Genetic information)-Unit 1.6

Question 1

What type of cells does mitosis produce? (3)

Answer 1

Two identical daughter cells
Diploid
For growth and repair of tissues

Question 2

At which stage of mitosis do chromosomes line up along the centre of the cell?

Answer 2

Metaphase.

Question 3

During what stage of mitosis are chromatids pulled to opposite poles of the cell?

Answer 3

Anaphase.

Question 4

What is the first stage of mitosis?

Answer 4

Prophase.

Question 5

What is the second stage of mitosis?

Answer 5

Metaphase.

Question 6

Name the third stage of mitosis.

Answer 6

Anaphase.

Question 7

What is the final stage of mitosis?

Answer 7

Telophase.

Question 8

What happens to the nuclear membrane during the telophase of mitosis?

Answer 8

It reforms.

Question 9

During what phase are the chromatids finally considered chromosomes again during mitosis?

Answer 9

Telophase.

Question 10

What do the chromosomes do during the telophase of mitosis?

Answer 10

Uncoil and lengthen.

Question 11

What happens to the spindle and nucleolus during the telophase of mitosis?

Answer 11

Spindle breaks down and nucleolus reappears.

Question 12

What are chromsomes made up of?

Answer 12

One long molecule of DNA which is wound in histone proteins to make DNA coil tightly for support.

Question 13

Why is mitosis needed?

Answer 13

For growth of multicellular organisms and repairing damaged tissue.

Question 14

Give some examples of what happens during the interphase of mitosis.

Answer 14

• Replication of DNA
• Making new organelles
• Synthesis of ATP and ribosomal material
• Increase in cell size (not growth)

Question 15

List the cell cycle: (3)

Answer 15

1.Interphase
2.Mitosis
•Prophase
•Metaphase
•Anaphase
•Telophase
3.Cytokinesis

Question 16

What is a centromere?

Answer 16

The specialised region in which chromatids are joined.

Question 17

What are homologous pairs?

Answer 17

Matching pairs

Question 18

What is the difference between diploid and haploid cells?

Answer 18

Diploid- total number of chromosomes (body cell)

Haploid- half number of chromosomes (gametes)

Question 19

What happens during the interphase? (5)

Answer 19

• Replication of DNA
• Replication of organelles that have their own DNA (mitochondria & chloroplasts)
• Making new organelles that DO NOT have own DNA
• Synthesis of ribosomal material, ATP & proteins
• Increase in cell size

Question 20

What happens during prophase in mitosis? (5)

Answer 20

1. DNA condenses forming chromosomes
2. Chromatids become visible
3. Centrioles move to opposite poles
4. Protein microtubules form and spindle developed from pole to pole
5. Nuclear membrane disintegrates and nucleolus disappears.

Question 21

What happens during the metaphase in mitosis? (2)

Answer 21

1. Chromosomes arrange at equator of spindle and become attached to spindle fibres at centromere.
2. Contraction of spindle fibres draw individual chromatids apart.

Question 22

Describe the anaphase in mitosis. (4)

Answer 22

1. Is very rapid
2. Centromere spilts
3. Spindle fibres contract
4. Chromatids separate and pulled to opposite poles

Question 23

Describe the telophase in mitosis. (4)

Answer 23

1. Chromatids have reached piles and are referred to as chromosomes again.
2. They uncoil and lengthen.
3. Spindle breaks down.
4. Nucleolus reappears and nuclear membrane reforms.

Question 24

What does cytokinesis mean?

Answer 24

Cytoplasm splitting

Question 25

Mitosis lacks genetic variation. What is an advantage and disadvantage of this?

Answer 25

Ability to increase numbers quickly to take advantage of an ideal environment. Lack leads to inability to adapt if environment changes.

Question 26

How does cancer form?

Answer 26

Result of uncontrolled mitosis. Cancerous cells divide repeatedly with no control, with the formation of a tumour. Thought to stem from mutations occurred in genes that control mitosis.

Question 27

What cells does meiosis produce?

Answer 27

4 genetically different daughter cells that are haploid.

Question 28

What happens in prophase 1

Answer 28

Paternal & maternal chromosomes associate as homologous pairs. (each pair called bivalent)

Question 29

Metaphase 1:

Answer 29

Maternal & paternal chromosomes (bivalents) arrange randomly in equator- source of genetic variation.

Question 30

Anaphase 1:

Answer 30

Homologous pairs are separated. Centromere DOES NOT SPLIT. Chromosomes remain intact at this stage.

Question 31

Telophase 1:

Answer 31

The first meiotic division. Chromosomes remain in condensed form. Cytokinesis occurs after, followed by meiosis 2. (animal cells)

Question 32

Prophase 2:

Answer 32

New spindle develops at right angles to old ones

Question 33

Metaphase 2:

Answer 33

Chromosomes line up separately on spindle fibres. | Each chromosome is attached to spindle by centromere.

Question 34

Anaphase 2:

Answer 34

Spindle fibres contract. Centromere spilts. Chromatids pulled to opposite poles.

Question 35

Telophase 2:

Answer 35

Chromatids lengthen and spindle disappears. | Cytokinesis takes place.