chapter 16 Flashcards
describe asexual reproduction
the process that produces genetically identical offspring from 1 parent
Describe some properties of asexual reproduction
- does not involve gametes or fertilisation
- only 1 parent required , so no variation and no mixing of genetic info
- offspring is genetically identical
identify examples of asexual reproduction
- plants
- bacteria via binary fission
identify advantages of asexual reproduction
only 1 parent needed
no gametes needed
no fertilisation needed
less energy needed
good characteristics passed onto offspring
population can be increased rapidly with right conditions
time and energy efficient
faster than sexual reproduction
identify disadvantages of asexual reproduction
less or no adaptations to changing evironment
increase risk of extinction
less or no resistance to disease
natural selection cannot occur
describe sexual reproduction
a process involving the fusion of the nuclei of 2 gametes to form a zygote and the production of offspring that are genetically different from each others
describe fertilisation
the fusion of the nuclei of gametes
describe the difference of gametes and zygote
Gametes
- sex cell
- contain half the number of chromosomes 23
- haploid nuclei
Zygote
male and female gametes fuse together
diploid nucleus ( 46 chromosomes )
describe the advantages of sexual reproduction
has variation
has adaptation to changing environment
lower risk of extinction
has resistance to some disease
natural selection can occcur
describe the disadvantages of sexual reproduction
2 parents required
gametes and fertilisation needed
more energy
difficult for isolated members to reproduce
state the structure of flowering plants and the functions
Sepal - protect flower bud
Petals - colourful, attract insects
Anther - produce pollen ( male gametes ), meiosis occur
Filaments - supports anther
Stigma - receive pollen
Style - connect stigma to ovary
Ovary - contains ovule
Ovule - contain female gametes , for fertilisation
Describe the differences between insect and wind pollinated flowers
Insect - pollinated :
Petals - bright & colourful
Scent & Nectar - present
Number of pollen - small amounts
Feature of pollen - sticky and spicky, larger , heavier
Anther - inside flower, to allow insect to brush against them while taking nectar
Stigma - inside the flower , to receive pollen easily as insect brush against them
Wind-pollinated :
Petals - dull and small
Scent & Nectar - not present
Number of pollen - large quantities
Feature of pollen - light and small, smooth
Anther - hangs outside, to release pollen easily as wind blows
Stigma - Hard outside , feathery to increase surface area to catch pollen
Describe pollination
the transfer of pollen grains from an anther to a stigma
Describe self pollination
The transfer of pollen grains from anther to stigma within the same plants
Describe cross pollination
The transfer of pollen from anther to stigma of different plants but same species
Describe the advantages of self pollination
no pollinators needed
less / no wastage of pollen
higher chance of pollination and fertilisation