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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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