2.3 b) Meiosis

Question 1

Meiosis is the ___ of the ___ which results in the production of ___ gametes from a ___ ___.

Answer 1

division, nucleus, haploid, diploid gametocyte

Question 2

A gametocyte is a cell which ___ (by meiosis) to form ___.

Answer 2

divides, gametes

Question 3

In diploid cells, chromosomes typically appear as ___ ___.

Answer 3

homologous pairs.

Question 4

Homologous chromosomes are chromosomes of the same ___, ___ ___, and sequence of ___ at the same loci.

Answer 4

size, centromere position, genes

Question 5

Meiosis is split into which stages?

Answer 5

Meiosis I and Meiosis II

Question 6

The chromosomes (which replicated ___ meiosis I) each consist of two genetically ___ chromatids, attached at the ___.

Answer 6

before, identical, centromere

Question 7

During meiosis I the chromosomes ___ and the ___ chromosomes line up along the ___ of the ___.

Answer 7

condense, homologous, equator, spindle. (They line up perpendicular to the equator)

Question 8

___ form at the points of contact between the non-___ chromatids of a ___ pair, and sections of ___ are ___.

Answer 8

Chiasmata, sister, homologous, DNA, exchanged

Question 9

What is a chiasmata?

Answer 9

the point at which non-sister chromatids of a homologous pair touch/cross over, before sections of DNA are exchanged

Question 10

The crossing over of non-___ ___ occurs at a chiasmata, resulting in new ____ of ___ in the affected ____.

Answer 10

non-sister chromatids,
combinations, alleles, genes

Question 11

Linked genes are those in the ___ ___.

Answer 11

same chromosome (they are close together)

Question 12

The exchange of DNA sequences at a chiasmata leads to the ___ of ___ of linked genes.

Answer 12

recombination, alleles. (Linked genes are more likely to stay together when sections of DNA are exchanged at the chiasmata -as they are close together)

Question 13

The transfer of DNA at a chiasmata is ___, and produces genetically ___ recombinant ___.

Answer 13

random, different, chromosomes

Question 14

Recombination is responsible for the production of genetically different ___.

Answer 14

gametes

Question 15

Spindle fibres attach to the ___ ___ and line them up parallel to the…

Answer 15

homologous pairs, equator of the spindle

Question 16

The ___ of the pairs of ___ ___ at the equator is ___.

Answer 16

orientation, homologous chromosomes, random

Question 17

Each pair of ___ ___ is positioned ___ compared to the other pairs at, the equator of the spindle.
They are arranged irrespective of their ___ or ___ origin.
This is known as ___ ___.

Answer 17

homologous chromosomes, independently, maternal, paternal.

independent assortment

Question 18

What is independent assortment?

Answer 18

the fact that homologous chromosomes are positioned independent of the other pairs, regardless of its maternal or paternal origin.

Question 19

Chromosomes of each ___ pair are separated, and move towards ___ ___ of the cell.
Then ___ occurs, creating two ___ ___.

Answer 19

homologous, opposite poles.
cytokinesis, daughter cells

Question 20

In meiosis II, each of the two cells produced in ___ _, undergoes a further ___ in which the ___ ___ of each ___ are separated.

Answer 20

meiosis I, division, sister chromatids, chromosome.

Question 21

At the end of meiosis II, a total of _, ___ cells are formed.

Answer 21

4, haploid (tho the cells produced in meiosis 1 were also haploid, just with two chromatids per chromosome)

Question 22

What happens in meiosis I?

Answer 22

1. the (homologous) chromosomes condense and line up along the equator.
2. sections of DNA are exchanged between non-sister chromatids at the chiasmata.
3. Spindle fibres attach to the homologous pairs and line them up along the equator of the spindle. (independent assortment happens)
4. The chromosomes are pulled to opposite poles of the cell.
5. cytokinesis happens, producing 2 haploid cells

Question 23

What happens in meiosis II?

Answer 23

the 2 haploid cells produced in meiosis I divide into 4 haploid gametes

Question 24

During the Prophase of Mitosis, the chromosomes (condense/decondense), and they (condense/decondense) during the Telophase.
At the start of Meiosis I, the chromosomes (condense/decondense).

Answer 24

Prophase: condense
Telophase: decondense
meiosis I: condense