Flashcards in Ch 30 Seed Evolution in Gymnosperms Deck (31):
Consists of an embryo and nutrients
What surrounds the seed?
A protective seed coat
Why are plant seeds an advance in the evolution of life on land?
They enabled the plants that possessed them to become the dominant producers in most terrestrial ecosystems
In addition to seeds, the following are common to all seed plants:
1) Reduced gametophyte
In nonvascular plants, what is the dominant free-living stage?
In seedless vascular plants, what is the dominant free-living stage?
What is true of the gametophytes of seed plants?
They develop within the walls of the spores and are retained within tissues of the sporophyte
The ancestors of seed plants were likely homosporous or heterosporous?
Possessing one type of sporangia
Seed plants are homosporous or heterosporous?
Possessing male and female sporangia
Give rise to the female gametophyte (produces eggs)
Give rise to the male gametophyte (pollen grains)
An ovule consists of:
3) One or more protective integuments
What occurs once a pollen grain reaches the ovule?
It extends a pollen tube that discharges sperm into the female gametophyte within the ovule
Advantages of seeds over spores:
1) Can remain dormant for days to years until conditions are favorable for germination
2) Have supply of stored food
3) May be transported long distances by wind or animals
Two groups of seed plants:
Seeds are exposed on groups of sporangia that form cones
Flowering plants with seeds within fruits
Four phyla of gymnosperms
One living species, Ginko biloba
Gnetum, Ephedra, and Welwitschia
Conifers (pine, fir, redwood, etc.)
Have large cones
Are cycads palms?
NO! Palms are angiosperms and cycads are gymnosperms
What is the largest gymnosperm phyla?