Reproduction in Plants Flashcards
What is sexual reproduction?
Is when there are two parents and there are two gametes which fuse in fertilisation and the offspring shares the genes of both parents.
What is asexual reproduction?
Is when there is only one parent, no gametes and no fertilisation occurs. The offspring is genetically identical to the parent.
What are the advantages of sexual reproduction?
-Variation
-Adapt and evolve quicker
DIS: slower, longer to grow family, don’t pass on many of your genes
What are some aspects of sexual reproduction in plants
- Sex cells are formed by meiosis
- Pollen grains are produced in the anther of the stamen
- Pollen contains the plant’s male gametes called sperm
- Ova are produced in the ovules and are the female gamete
What are the different ways pollination can occur?
Wind, Insect
How is the position of the stamen different for wind pollinated and insect pollinated flowers?
- Wind: Exposed so that wind can easily blow pollen away
- Insect: Enclosed within flower so that insect must make contact
How is the position of the stigma different for wind pollinated and insect pollinated flowers?
- Wind: Exposed to catch pollen blowing in the wind (hanging outside flower)
- Insect: Enclosed within flower so that insect must make contact
How is the type of stigma different for wind pollinated and insect pollinated flowers?
- Wind: Feathery to catch pollen blowing in the wind
- Insect: Sticky so pollen grains attach from insects
How is the size of petals different for wind pollinated and insect pollinated flowers?
- Wind: Small
- Insect: Large to attract insects
How is the colour of petals different for wind pollinated and insect pollinated flowers?
- Wind: Not brightly coloured, usually green (not waste energy to make this as not needed?)
- Insect: Brightly coloured to attract insects
How is the nectaries different for wind pollinated and insect pollinated flowers?
- Wind: Absent
- Insect: Present (nectar is a ‘reward’ for insects)
How is the pollen grains different for wind pollinated and insect pollinated flowers?
- Wind: Smaller, smooth inflated grains to carry in the wind (large quantity)
- Insect: Larger, sticky grains to stick to insects’ bodies
Why do plants generally ensure that they cross pollinate?
Greater chance of genetic variation
What is fertilisation?
The fusion of female and male gametes to produce a zygote in sexual reproduction, that undergoes cells division and develops into an embryo
Describe plant fertilisation
- Pollen lands on stigma on carpel
- Pollen tube grows down the style and enters the ovary and then enters the ovule through the micropyle
- The pollen then enters the ovum where it is fertilised to become a zygote
- There are also polar nuclei which are also fertilised to form cotyledons which provide a food source to the zygote
What is the female part of the plant called?
The carpel
What is the function of the stigma?
The platform on which the pollen lands
What is the function of the style?
A stalk which holds and supports the stigma in the best position
What is the function of the ovary?
A hollow chamber which contains the female gametes inside ovules. The ovules develop to form the walls of the ovary
What is the function of the micropyle?
Entry point for the male nucleus at fertilisation
What is the male part of the plant called?
The stamen
What is the function of the anther?
Contains four pollen sacs filled with pollen grains. Each pollen grain contains a male gamete.
What is the function of the filament?
A long stalk that holds and supports the anther in the best position to release pollen onto a visiting insect.
What is cross pollination?
Cross pollination is when pollen from a flower is transferred to the stigma of another flower (Sexual reproduction). They rely on insects or wind to help them pollinate.