2.7

Question 1

What is sexual reproduction?

Answer 1

The formation of offspring from the fertilisation of two germline cells.

Question 2

How are offspring with genetic variability produced?

Answer 2

When a male and female gamete fuse and a new cells with two sets of chromosomes is formed.

Question 3

Name the stages of meiosis

Answer 3

Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Anaphase 2, Telophase 2, and Cytokinesis.

Question 4

What are the two sections of meiosis?

Answer 4

Meiosis 1 and Meiosis 2

Question 5

What is “crossing over” in prophase 1?

Answer 5

When non-sister chromatids touch, break, and re-join, exchanging genetic material whilst lined up in the centre of the cell ready to split the chromatids to divide.

Question 6

What are sister chromatids?

Answer 6

The identical duplicated copies of a chromosome, joined together by a common centromere.

Question 7

What is a homologous pair?

Answer 7

Two chromosomes paired together with the same length, centromere position, and specific gene location.

Question 8

Describe independent assortment

Answer 8

During metaphase 1, each homologous pair lines up at the metaphase plate in a random orientation, with their paternal or maternal chromatid facing random poles. Because of this, the first meiotic division results in daughter cells with its maternal and paternal chromatids sorted with random combinations.

Question 9

Why is crossing over and independent assortment importance?

Answer 9

So there is genetic variation in daughter cells.

Question 10

What are the products of mitosis and meiosis?

Answer 10

Mitosis produces two cells with the same number of chromosomes as the parent cell. Meiosis produces four cells with a half of the number of chromosomes than the parent (from diploid to haploid).

Question 11

What is the difference between mitosis and meiosis?

Answer 11

Mitosis results in a diploid parent cell splitting into two diploid daughter cells, genetically identical to the parent. Meiosis results in a diploid parent cell splitting into 4 haploid daughter cells with genetic variation. Meiosis involves two cell divisions, mitosis only has one division.

Question 12

Define fertilisation

Answer 12

The process of the fusion of a haploid maternal egg cell and haploid paternal sperm cell.

Question 13

Define the term gamete

Answer 13

a reproductive cell in an animal or plant

Question 14

What occurs during prophase 1?

Answer 14

Chromosomes condense and become visible, homologous pairs sit together as a pair, nuclear envelope is broken down, crossing over occurs, spindle fibres are produced and begin to move the homologous pairs towards the metaphase plate.

Question 15

What occurs during metaphase 1?

Answer 15

spindle fibres arrange homologous pairs at the equator of the cell, independent assortment occurs.

Question 16

What occurs during anaphase 1?

Answer 16

homologous pairs are separated by spindle fibres which move the whole chromosomes to opposite poles.

Question 17

What occurs during telophase 1?

Answer 17

Two haploid sets of chromosomes are located at each pole, spindle apparatus disappears, new nuclear enveloped begin to form.

Question 18

What occurs during cytokinesis 1?

Answer 18

A cleavage furrow forms and two haploid daughter cells are produced.

Question 19

What occurs during prophase 2?

Answer 19

New spindle apparatus form in each cell, sister chromatids begin moving towards the metaphase plates.

Question 20

What occurs during metaphase 2?

Answer 20

chromosomes are positioned at the centre of the metaphase plate.

Question 21

What occurs during anaphase 2?

Answer 21

Centromeres divide and sister chromatids are pulled apart towards opposite poles, each chromatid is now known as individual chromosomes as counted by their centromeres.

Question 22

What occurs during telophase 2?

Answer 22

Nuclear membrane reform and nucleoli reappear for each cell.

Question 23

What occurs during cytokinesis 2?

Answer 23

Division of cells occur to form four haploid daughter cells, each with a haploid set of genetically different, unduplicated chromosomes.

Question 24

Define diploid

Answer 24

having two complete sets of chromosomes

Question 25

Define haploid

Answer 25

having one single set (half of diploid) of unpaired chromosomes.

Question 26

What is a zygote?

Answer 26

The fertilised egg cell

Question 27

What is the difference between daughter cells of sexual and asexual reproduction?

Answer 27

Daughter cells of asexual reproduction are genetically identical to the parent cell. Sexual reproduction results in genetically unique daughter cells being produced from two parents that contribute different genetic information.

Question 28

What is a diploid number and haploid number?

Answer 28

Diploid number is the number of chromosomes in a cell with paired chromosomes. Haploid number is the number of single chromosomes in a cell with unpaired chromosomes.

Question 29

When is DNA replicated in the cell cycle?

Answer 29

Interphase

Question 30

What is chiasmata

Answer 30

The point where overlapping occurs during crossing over.

Question 31

What is a recombinant chromosome?

Answer 31

Results of crossing over, individual chromosomes that carry genes from two different parents.

Question 32

What is synapsis?

Answer 32

The pairing of each chromosome from each parent, allowing crossing over to occur in meiosis