Section 27.1 (Exam 2) Flashcards
Pollen, Seeds, and Wood Contributed to the Success of Seed Plants
What are the 3 innovations of gymnosperms and angiosperms that allowed plants to colonize drier habitats and spread across earth?
Woody stems, pollen grains, and seeds
Woody stems appeared in ____________________, seedless vascular plants which are now extinct.
progymnosperms
What is the benefit of pollen grains?
Transfer of sperm no longer requires water
What is the function of seeds?
Protect the embryo until conditions are ideal for germination
The first seed plants were _______________, which are now extinct.
woody seed ferns
Living seed plants fall into which two groups?
Gymnosperms and angiosperms
Gametophyte generations in seeded plants are ____________ dependent on the sporophyte and highly ___________.
nutritionally; reduced
Seed plants are ________________ because they contain both megaspores and microspores.
heterosporous
Microspores divide mitotically to produce ________________.
pollen grain
Pollen grain walls contain ________________, the most resistant biological compound known; prevents dehydration and chemical damage.
sporopollenin
Megaspores of seeded plants are not shed, they remain within the ________________.
megasporangia
One haploid megaspore develops into the female gametophyte by ____________.
mitosis
The megasporangium and its protective integument form the _______, which develops into the seed after fertilization.
ovule
______________ is when a pollen grain lands near a female gametophyte.
Pollination
A ____________ elongates and digests its way through the sporophyte tissue to the megagametophyte.
pollen tube
__________ are released from the pollen tube and fertilization results in a ________________.
Sperm; diploid zygote
The diploid zygote divides mitotically to become an _____________________.
embryonic sporophyte.
The embryo enters a dormant stage and the result is a multicellular ____.
seed
Seed tissues contain _________ generations.
three
The seed coat develops from the ____________, the diploid sporophyte parent.
integument
The haploid female gametophytic tissue provides ___________ for the developing embryo.
nutrients
The embryo is the new ______________________ generation.
diploid sporophyte
The earliest seed plants had thickened woody stems, produced by _________________.
secondary growth
Wood, or secondary _______, gives support and allows plants to grow above their competitors.
xylem
Many seed plants have lost the _____________ habit, but have other adaptations.
woody growth
