Topic 11 - seed plants gynopserms Flashcards
what changes do seed plant have in dominance?
- they have sporophyte dominant and gametophyte dependent on the sporophyte.
what changes do seedless vascular plants have in dominance?
- have sporophyte dominant, but gametophyte is still independent.
explain the changes in dominance in mosses and other nonvascular plants?
- Gmateophyte –> dominant
- sporophyte –> reduced and dependent on gametophyte for nutrition
explain the changes in dominance in ferns and other seedless vascular plants
- gametophyte –> reduced and independent
-sporophyte –> dominant
explain the changes in dominance in seed plants (gymnosperms and angiosperms)
- gametophyte –> reduced and dependent on surrounding sporophyte tissue for nutrition
- sporophyte –> dominant
what are the five features of seed plants?
- Independent sporophyte and dependent gametophyte
- heterospory
a. (almost all seedless plants are homosporous, but all seed plants
produce two sizes of spores, megaspores and microspores) - ovules
a. an ovule is a megaspore retained within parent sporophyte - Pollen
a. (microspores develop into pollen grains) - seeds
a. (fertilized ovule develops into seed containing next-generation
sporophyte)
what is a megaspore?
-spore develop into female gametophytes (1n)
what is a microspore?
- spore developed into male gametophytes
where is the megaspore produced?
- it is produced within the sporophytes megasporangium (2n) which is wrapped in an extra layer called an integument (2n)
what is a megasporangium?
- where the megaspore is produced.
- it is diploid
what is an ovule?
- a combination of integuement + megasporangium +megaspore
what is an ovum?
- means egg
where are the male haploid microspores retained?
- they are retained in the 2n microsporangium, which is on the parent sporophyte.
what do male microspore undergo?
- they undergo mitosis to produce very tiny haploid male gametophytes which is often immature pollen.
how many cells does a pollen grain have?
- it has 2
- one is generative and one is a tube cell
- they both produce sperm and pollen tube.
what are pollen grains coated with?
- they are coated with sporopollenin, which makes them tough.
what does this tough coat help them withstand?
- drying, UV, and
physical bashing
what happens in the pollen reaches an ovule?
- it is lucky and can pollinate and then fertilize the ovule
what is pollen packaged as?
- single grains
or small clumps of 4, 8, or 16 grains
what do orchids produce?
- much
larger clumps with 1000’s to millions of
grains - it is called pollinia