Mitosis and meiosis

Question 1

What is mitosis

Answer 1

Cell division that produces two daughter cells genetically identical to the parent cell.

Question 2

What is the purpose of mitosis

Answer 2

Growth and repair

Question 3

Where does mitosis occur

Answer 3

In all stem cells/mother cells
e.g. skin, bone, blood, muscle

Question 4

How does mitosis occur

Answer 4

starts with one body cell with 46 chromosomes
the cell replicates all chromosomes once and then divides them
produces two new daughter cells each with 46 chromosomes

Question 5

What happens when mitosis goes wrong?

Answer 5

Cells begin to divide uncontrollably
Becomes cancer

Question 6

What does homologous mean?

Answer 6

Chromosomes are the same and contain the same genes in the exact same location

Question 7

Mitosis processes in order;

Answer 7

prophase, metaphase, anaphase, and telophase, then cytokinesis( overlaps ana and telophase)

Question 8

What occurs during first stage interphase?

Answer 8

DNA molecules duplicate and the centrioles replicate

Question 9

What occurs during first stage prophase?

Answer 9

Nucleolus disappears
-nuclear membrane breaks down
Chromosomes appear as pairs of chromatids
Homologous chromosomes migrate towards cell equator then condense
Centrioles migrate to opposing poles of molecule
Spindle forms between these poles

Question 10

What occurs during first stage metaphase?

Answer 10

Chromosomes line up on the cell equator
Each has a spindle fibre attached to it’s centromere

Question 11

What occurs during first stage anaphase?

Answer 11

Pairs of chromatids separate to now be referred to as chromosomes (double chromatids)
Chromosomes then pull apart at the centromeres towards opposite ends of the cell

Question 12

What occurs during first stage telophase?

Answer 12

Spindle disappears
Two nuclei form
One nuclear membrane
New nucleolus form in each new nucleus and each have diploid number (46 chromosomes)

Question 13

What occurs during cytokinesis?

Answer 13

Division of cytoplasm
Separating cell into daughter cells

Question 14

What is meiosis?

Answer 14

Cell division producing gametes with half the number of chromosomes of the parent cells (4 daughter cells)

Question 15

What is the purpose of meiosis?

Answer 15

To produce gametes for fertilisation

Question 16

Where does meiosis occur?

Answer 16

In sex organs i.e. testes and ovaries

Question 17

What occurs during second stage prophase?

Answer 17

Chromosomes migrate-move toward the equator of cell
New spindle forms between the poles

Question 18

What occurs during second stage metaphase

Answer 18

Chromosomes line up along the cell equator

Question 19

What occurs during second stage anaphase

Answer 19

Chromosome split apart at the centromere
Two chromatid moves to opposite poles of cell
Resulting in chromatids remaining intact
Chromatid from one chromosome being at each pole

Question 20

What occurs during second stage telophase

Answer 20

Nuclear membranes begin to form
Cytoplasm starts to divide (cytokinesis)
Four new cells formed (each have half number of chromosomes of original cell)

Question 21

What is meant by centromere?

Answer 21

The link between 2 chromatids

Question 22

What is a chromatid?

Answer 22

One of the two identical halves of a chromosome that has been replicated in preparation for cell division

Question 23

What is cancer?

Answer 23

Uncontrolled cell division

Question 24

What is a tumor?

Answer 24

Mass created by uncontrolled growth of abnormal cells

Question 25

Difference between malignant and benign tumours

Answer 25

Malignant- may spread through body through metastasis

Benign- cannot invade normal tissues, blood, or lymph vessels/other body parts
Can be removed due to the tumour being surrounded by a capsule

Question 26

Causes of cancer:

Answer 26

-carcinogens
-genetics

Question 27

Types of carcinogens

Answer 27

-UV radiation
-X-rays
-Ionising radiation
-Viruses
-Chemical carcinogens

Question 28

Cancer prevention:

Answer 28

-Education
-Legislation

Question 29

What is spermatogenesis

Answer 29

The formation of spermatozoa in the testis

Question 30

What is oogenesis

Answer 30

The formation of ova in ovary

Question 31

Where does spermatogenesis occur?

Answer 31

Occurs within the seminiferous tubules in each testis
-seminiferous tubules are lined with immature cells called spermatogonia

Question 32

Draw out process of spermatogenisis

Answer 32

1. 2n Spermatogonium
2. 2n spermatogonium (process mitosis) and 2N Spermatogonium
3. 2n primary spermatocyte
4. n x2 secondary spermatocytes (first meiotic division)
5. x4 n spermatids (secondary meiotic division)
6. x4 spermatozoa (maturation)

Question 33

Draw out process of oogonium

Answer 33

1. 2n oogonium
2. 2X 2n oogonium
3. 2n primary oocyte
4. x2 n secondary oocyte and first polar body (first meiotic division)
5. x2 n ootid and second polar body (second meiotic division
6. Mature ovum n