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How does the seta aid moss reproduction?
- Stores spores as they mature
- Releases the spores when the cap twists and falls off
- Located high off ground so spores can go farther
- Helps prevent overcrowding of plants
How do the antheridia and archegonia aid moss reproduction?
- Water stimulates the antheridia to release the sperm and it either swims or is splashed to the archegonia
- Archegonia is cup shaped to aid water splash
- It allows fertilisation to occur
- It means mosses are limited to a moist enviroment
How do spores aid moss reproduction?
- Is the embryo for the gametophyte plant, it needs to germinate in a moist area so that fertilisation can occur later on.
- Tough exterior and waterproof coat mean it isn't easily damaged and can survive dry areas
- Can survive months without germinating
How does the annulus aid fern reproduction?
- Ring of cells holding onto the sporangium in the sori
- It dries out, stretches backwards and then snaps forward flinging out the spores
- Allows ferns to colonise new areas and prevents overcrowding
How does the prothallus aid fern reproduction?
- Low lying so that water can cover it
- Water stimulates antheridia to release sperm which swim to the archegonia of another plant
- The archegonia releases a hormone attractant
- Antheridia and Archegonia develop at different times
- Limits ferns to a moist enviroment
How do spores help to aid fern reproduction?
- It is the embryo for the gametophyte plant, this mean it must germinate in a moist enviroment for fertilisation later on
- tough waterproof coat meaning it wont dry out and isn't easily damaged
- Can survive for months without germinating
How does seed dispersal aid angiosperm reproduction?
- Seeds grow fruit around them
- Animals eeat fruit and seeds are carried internally
- Helps colonise new areas and prevents overcrowding
How does the pollen tube assist angiosperm reproduction?
- Pollen grain lands on stigma, grows tube down to the ovaries allows fertilisation to occur
- Happens internally so not reliant on any external sources eg water for fertillisation to occur
- Doesn't restrict angiosperms on their enviroment which they can grow in
- Prevents gametes from being damaged
How does the stigma help angiosperm reproduction to occur?
- Stigma is higher than the anther which prevents self fertilisation from occuring
- This helps to increase the genetic diversity of the species
Compare and contrast sperm transfer mechanisms between the three species
- In mosses and ferns, sperm transfer happens externally and relies on water molecules to carry the sperm from the antheridia to the archegonia. It restricts ferns and mosses to moist enviroments
- In angiosperms, sperm transfer happens internally with the pollen grain landing on the stigma and the genetic material being transfered through a pollen tube. It doesn't rely on any external sources meaning that angiosperms aren't limited in their enviroment
Compare and contrast the dominance of the sporophyte generation between the three plant species
- The gametophyte is the main form of the moss with the sporophyte growing on top of the gaametophyte plant during fertilisation and being reliant on the gametophyte plant for survival
- In ferns the sporophyte plant is the main form. The gametophyte is a seperate plant called the prothallus which grows from a spore and is needed for fertilisation to occur. Once fertilisation has occurred the gametophyte plant grows into the sporophyte plantIn angiosperms, the gametophyte has been reduced to a 3-nucleus pollen grain and an 8-nucleus egg. This is because fertilisation happens internally so another plant isn't needed. It also means that angiosperms aren't limited in where they can grow by external resources
Compare and contrast how the three plants avoid self-fertilisation
- In mosses, the archegonia and antheridia are grown on different plants
- In ferns the antheridia and archegonia develop at different timesIn angiosperms, there is a nectary which encourages insects to perform cross pollinisation and the stigma is taller than the anther so that the wind can't blow the two into each other