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
what causes allergies?-
-proteins associated with sporopollenin
coat
what is pollination in general?
the process by which pollen moves from
male to female structures represents
another drastic change in tactics
what is pollination in non-seed plants?
- it is the single-celled
sperm that goes in search of eggs
– requires water to swim through
what is pollination in seed plants?
- entire male gametophyte
goes in the form of pollen
– wind, animals or (rarely) water can transport
pollen
what happens in the seed after the egg in the ovule is fertilized?
- the zygote undergoes mitosis to
produce an embryonic sporophyte
what is a seed?
- the sporophyte embryo in
gametophyte tissues that are
wrapped it a coat from its own parent
sporophyte
what is the main source of variation in seeds?
is amount of gametophyteproduced food
what is the disperal stage for most seed plants?
seed
what is the travelling stage for non-seed plants?
-spore
what protects the embryo and food supply?
- tough coat
How long can seeds remain dormant for?
- for days to many years
what do large seeds need to germinate and grow?
- need lot of food and can grow in low light
what do seeds with little food need to germinate and grow?
- they need light to grow into strong seedlings
what are the two main clades of extant seed plants?
- gymnosperms:
a. gymos =naked
b. sperm = seed
c. ovule and seed lie on surface of sporophylls - Angiosperms: (flowering plants)
a. angio = container,
vessel
what are sporophylls normally in?
- in cones
what are the 4 phyla of gymnosperms?
- Ginkgophyta
- Gnetophyta
- cyacadophyta
- coniferophyta
What is Ginkgophyta?
- has 1 species Ginkgo biloba
- all associated with human habitations
- common tree on the street and can withstand harsh environments
- sporophytes are large and woody
- separate male and female gametophytes
- sperm is flagellated, moves into the receiving female.
- fleshy coated seeds that smell awful.
what is ginkgophyta used for?
- increased blood flow
- improves memory
what is cadophyta?
- 300 species in tropical areas
- have flagellated sperm as a seed plant
- pollinated by insects
- separate male and female sporophytes. (large cones)
- females have cones with fleshy coated seeds. (they are poisonous)
- stem starch can be extracted and made into a sort of flour called sago.
what is gnetophyta?
- three genera with 76 species
- Gnetum –> 1/2 of sp
a. tropical trees and veins - welwitschia –> 1 sp in Africa. (gets moisture from morning fog, only has 2 leaves)
- Ephedra –> from deserts around the world (many contain alkaloids called epinephrine which is used to dilate lungs)
what is coniferophyta?
- has 600 sp
- named cuz of cones
- have clusters of sporophylls
- cone = cone
- fer = to bear
-usually are woody and trees some can be very tall and old.
- many have long needles (pine tree)
- many have scale-like leaves (small and densely packed)
- many have flat leaves (in humid environments, monkey-puzzle tree)
- many are evergreen and do not drop leaves in autumn.
- they are well adapted to cold, dry habitats
a. wax coating on leaves
b. photosynthesis in winter
c. early head start in making food right away in spring .
what is deciduous?
- leaves do drop annually.
- they do fall in fall.
How is the conifer species threat?
- fire and pests.
- pests because bark beetles bore into the trees and lay eggs
- they can also bring fungi in.
what can healthy conifers trees pinch out beetles with?
- pin resin –> which can be called pitch
what is amber?
- it is a fossilized resin.
- can be derived form angiosperms as well
Pine as a gymnosperm example?
- mature tree is 2n sprophyte
where are the sporangia located in a pine tree?
- on scale leaves (sporophylls) in clusters (cones)
do pines have a megasporangium (female) and a microsporangium (male) on the same tree?
true
how is pollen transported in pine tree?
- by wind
steps of a pine life cycle?
- each tree has an ovulate and pollen cones.
- The microsporophytes divide by meiosis, which produces micropores which develop into a pollen grain.
- The ovulate scale has 2 ovules and each contain a megasporangium.
- pollination takes place as the pollen reaches the ovule.
- pollen grain geminates and for a ming a pollen tube that lead sot the megasporangium.
- the megasporocyte undergoes meiosis producing four haploid cells. Only one survives as a megaspore.
- the megaspore develops into a female gametophyte. This contains 2 or 3 archegonia and each will form a egg.
- the eggs are mature, and the sperm has developed in pollen tube. The sperm is then leaded to the female gametophyte. This causes fertilization
- all eggs are fertilized but only one zygote develops into an embryo.
- the ovule becomes a seed , consisting of an embryo , food supply and seed coat.
