6.3 Meiosis

Question 2

meiosis produces:

Answer 2

haploid cells (and genetic variation by independent assortment and crossing over). aka gametes for sexual reproduction

Question 3

in sexual reproduction two ….. fuse in fertilisation to form ……

Answer 3

gametes, zygote

Question 4

Meisosis occurs

Answer 4

the testes and ovaries;

Question 5

significance of mitosis in life cycles

Answer 5

To include growth, tissue repair and asexual
reproduction in plants, animals and fungi.

Question 6

meiosis process is known as

becuase it forms haploid cells

Answer 6

reductive division

Question 7

humans have how many chromosones?

Answer 7

46

Question 8

humans have how many chromosone pairs

Answer 8

23 one from mum one from dad

Question 9

homologous chromosone pairs have the same…..

Answer 9

genes but different versions/variants of the gene aka alleles

Question 10

stages of meiosis

Answer 10

pmat 1
pmat 2

Question 11

what happens in prophase 1

in bold is dif to mitosis

Answer 11

• chromosones condense
• nuclear envelope dissolves
• spindle formation begins
• homologous chromosones pair up and form biavlents
• chromatids entangle aka crossing over

Question 12

what happens in metaphase 1

Answer 12

• homologous pairs of chromosones line up along the metaphase plate
• orientation of homologous pairs is random and independent of other paris aka independt assortment aka dif allele facing dif poles aka genetic variation

Question 13

what happens in anaphase 1

Answer 13

• chromatids centromeres stay intact
• homologous pairs get pulled to either poles
• sections of dna that were entangled during crossing over are exhanged at the point of chiasmata this exchange forms recombiant chromatids aka genetic variation sister chromatids are no longer identical

Question 14

what happens in telophase 1?

Answer 14

• chromosones assemple at opposite poles
• nuclear membrane reforms
• chromosones uncoil
• cytokenisi begins
• diploid cells are now haploid

Question 15

what happens in prophase 2?

Answer 15

• chrromosones that still consist of two chromatids condense
• nuclear envelope breaks down
• spindle fibre formation begins

Question 16

what happens at metaphase 2

Answer 16

• chromosones assemble on the metaphase plate
• **due to the crossing over chromatids arent identical and so independednt assortment occurs again and more genetic variation occurs **

Question 17

what happens at anaphase 2?

Answer 17

• chromatids are pulled to opposit poles by shortening spindles fibres
• centromeres divide

Question 18

what happens in telophase 2?

Answer 18

• chromosones unravel and from chromatin again
• nuclear envelope reforms and nucleas reforms
• cytokenesis occurs
• 4xhaploid cells dut to reduction division all genetically def due to crossing over and independent assortment