Seed Plants Flashcards
What are the seed plants?
Gymnosperms and Angiosperms
When did they emerge?
360mya in the Permian
What is a seed?
Its embryo and food supply, surrounded by a protective coat
How have seed plants affected human society?
cultivation of cereal crops and domestication a massive cultural change, transformation to permanent settlers
What are the derived traits of seed plants?
Reduced gametophytes, heterospory, ovules, and pollen
What is the evolutionary trend in gametophytes?
reduction in size, until microscopic in most seed plants
What does a seed allow plants to do?
Reproduce and survive in a broader range of environments
Where do gametophytes of seed plants live?
In the sporangia of the sporophyte
What benefits come from gametophyte retained in the sporangia?
Moist reproductive tissue shield gametophyte from UV and can obtain nutrients from sporophyte
What is heterospory?
Megasporangia produce megaspores which give rise to female gametophytes and microsporangia produce microspores which gives rise to male gametophytes
What is the integument?
layer of sporophyte tissue , envelops and protects the megasporangium
How many integuments are present in Gymnosperms
1
How many integuments are present in angiosperms?
2
What is the ovule?
structure comprised of the megasporangium, megaspore and integument
What happens inside the ovule?
a female gametophyte develops from a megaspore, and produces the eggs.
What does the microspore develop into?
A pollen grain, consisting of male gametophyte enclosed within the pollen wall
What is pollination?
The transfer of pollen to the part of a seed plant that contains ovules
What happens when the pollen grain germinates?
gives rise to a pollen tube that discharges sperm into the female gametophyte
What did the evolution of the seed mean for reproduction?
No dependence on free water, could travel further distances to fertilise
What happens after pollen fertilises the female gametophyte?
Ovule develops into a seed
How does the seed coat form?
From the integument
What are the benefits of the seed having food supply?
Can be dormant for a long time after being released from the parent, and can germinate under favourable conditions with food supply providing critical nutrients for growth
