Sexual Reproduction Flashcards
1
Q
What is sexual reproduction?
A
- Involves two parents, one male and one female
- Each parent produces many haploid gametes by meiosis
- one male and one female gamete fuse in fertilisation to produce a diploid cell/zygote
2
Q
Why is sexual reproduction important?
A
- creates new combinations of exisiting genetic variation
- a large gene pool helps it to survive when conditions change
- if a species has a large gene pool, it is likely that at least some individuals will have alleles to enable them to survive new threat.
3
Q
How do new alleles arise ?
A
- are always created by mutations
- sexual reproduction creates new combinations of exisiting genetic variation.
4
Q
Differences between sexual and asexual reproduction?
A
- Asexual
- Quicker
- no males needed
- very little genetic variration
- only die to mutation
- Sexual
- takes time to find a male
- lot more genetic variation
- meiosis - crossing over, independent assortment
- survival to genetic variation
5
Q
How does crossing over increase genetic variation?
A
- prophase 1
- chromatids twist around each other and swap alleles
- recombinants contains the same genes by new combinations of alleles
6
Q
How does independent assortment increase genetic variation?
A
- each pair of maternal and paternal chromsomes aligns independently of other - maternal or paternal can face either pore
- creates unique combinations
7
Q
What is independent assortment of chromatids?
A
- metaphase 2
- each replicate chromsomes aligns in a position that is independent of the previous on the metaphase plates
- This creates unique combinations of chromatids in each daughter cell of the second division.
8
Q
What is Random fertilisation?
A
- any sperm can fertlise any egg
- each individual is unlike any to have existed before any that will exist again.
9
Q
How many possibilities are there?
A
- 2X - where ‘x’ is number pairs of chromosomes
