Seed Plants And Gymnosperms Flashcards
What is the advantage of having pollen
Water is not required as a medium for reproduction
Seeds can lay dormant until conditions for germination are optimal
What the four main groups of gymnosperm plants
Cycads
Ginkgos
Gnetophytes
Conifers
What are the characteristics of seeded plants
Produce pollen
Produce seeds
Contain wood
What innovations led to the diversification of seed plants
Seed plants are heterosporous
The seed is a well protected resting stage
They form wood which allows them to grow outwards
How is pollen produced
Microsporangium divides via mitosis to form microspores
These microspores then divide to form the male gamete (pollen)
What is the microspores and macrospore
Microspores: develop into male gamete, pollen
Megaspores: develop into female gamete, ovules
How are female gametes formed
Megasporangium divides through meiosis
Remaining megapode divides into female gametophyte
What happens during pollination
Pollen lands near a female gametophyte
What are the three generations within seeds
Seed coat: develops from integument
Haploid female gametophyte tissue: supplies nutrients for developing embryo
Embryo: the new sporophyte generation
What does gymnosperm mean
Naked seeds
Ovules and seeds are not protected by ovary or fruit tissue
What are the characteristics of cycads
Palm like plants
Possible the earliest living clade
Many toxic species
What are the characteristics of ginkgos
Only one species (rest are extinct)
Common during the Mesozoic
Male and female trees are separated
Have chromosomal gender determination
What are the characteristics of Gnetophytes
Long lived desert plants
Strap like leaves that sprawl on the sand
Long deep set roots
What are the characteristics of conifers
Most abundance of the gymnosperms
Contains male cones and female cones
Often extremely tall and long lived
Some have fleshy fruit like tissue round the seeds (not true fruit)
