meiosis

Question 1

meiosis

Answer 1

cell division of sex cells

Question 2

karyotype

Answer 2

a complete set of chromosomes arranged according to shape size and number in a organism

Question 3

where does meiosis take place in animals

Answer 3

in the gonads (reproductive cells) , testes in the male and ovaries in the female

Question 4

what is are cells produced by meiosis

Answer 4

gametes [ gametes are formed through the process gametogenesis]
in the male sperm cells are produced, through the process spermatogenesis and in the female egg cells are produced , through the process of oogenesis

Question 5

what are plant gametes called

Answer 5

spores

Question 6

where does meiosis occur in plants

Answer 6

in the anthers to produce pollen grains in the male and in the ovary to produce ovules in the female

Question 7

interphase

Answer 7

DNA replication takes place where the chromosomes duplicate and the genetic material is doubled
the two copies of chromosomes are called homologous pairs

Question 8

meiosis 1

Answer 8

a reduction division where the diploid cell is separated to create 2 haploid cells.

Question 9

prophase 1

Answer 9

• the spindle is formed
• the chromatin network contracts and the single threaded chromosomes become visible
• the nuclear membrane and and nucleolus disappear
• the chromosomes arrange themselves and pair homologously
• the homologous chromosomes lie next to each other and at the chiasma ( a point along the chromatid) the chromatids cross over and genetic material is exchanged

Question 10

metaphase 1

Answer 10

• the spindle extends across the whole cell
• the homologous pair arrange themselves at the equator
• the spindle fibers attach to the centrosome of the homologous pairs

Question 11

anaphase 1

Answer 11

the spindle contracts and the homologous pairs separate and they move tp the opposite ends of the cells poles

Question 12

telophase 1

Answer 12

the spindle disappears
the nucleus membrane and nucleolus form
the cytoplasm divides thus forming 2 haploid cells with different genetic materials due to crossing over

Question 13

meiosis 2

Answer 13

• the 2 daughter cells from meiosis 1 divide again

- the centromeres of these daughter cells separate resulting in 4 haploid cells

Question 14

prophase 2

Answer 14

• nucleus membrane and nucleolus disappear
• spindle threads form
• the daughter cells are now visible as chromatids

Question 15

metaphase 2

Answer 15

• the spindle threads extends across the cell
• the sister chromatids arrange themselves at the equator
• the spindles attach to the centromeres of the daughter cells

Question 16

anaphase 2

Answer 16

the spindle fibres contract ,then separating the sister chromatids and pulling them to the opposite poles of the cell

Question 17

Telophase 2

Answer 17

-the spindles disappear
-the nucleus membrane and nucleolus reform
-the cytoplasm divides thus resulting in 4 haploid daughter cells
the new daughter cells are genetically different from each other

Question 18

genome

Answer 18

set of genes in a organisms haploid set of chromosomes

Question 19

what is the importance of meiosis

Answer 19

• it ensures genetic variation
• it prevents the doubling effect of fertilisation
• it results in the formation of mature gametes in the process of gametogenesis

Question 20

gametogeneiss

Answer 20

process whereby gametes are formed

Question 21

explain how the random arrangement of chromosomes results in genetic variation

Answer 21

• at the equator each homologous chromosome pair is randomly arranged , which results in the random separation of chromosomes
• the paternal and maternal chromosomes randomly move to opposite poles of the cell, this ensures that the combination of genetic material received by each gamete is random

Question 22

explain how crossing over allows for genetic variation

Answer 22

crossing over results in the exchange of genetic material between the paternal and maternal homologous chromosome pairs , a new genetic combination occurs between the exchanged chromosomes , this ensures that all the gametes have a unique gene combination

so when the gametes of the same parents come together for fertilisation the resultant offspring will have a unique karyotype thus ensuring variation in the offspring

Question 23

what is non-disjunction

Answer 23

when one pair of chromosomes does not separate and the one cell receives two copies of chromosomes and the other cell doesnt

Question 24

explain where does non-disjunction occur

Answer 24

it happens during anaphase 1 when the homologous chromosomes do not separate or in anaphase when the sister chromatids do not separate