Chapter 22 Flashcards
Novel Features of Tracheophytes
- Embryo: zygote retained, nourished by gametophyte (matrotrophy)
- Cuticle
- Stomata,
- Spores made of sporopolenin (decay resistant)
- Sporic life cycle
- Vascular Tissue (xylem & Phloem)
when did seed plants originate?
Seed plants (gymnosperms and angiosperms) originate 365 MYA
gymnosperms divisions
Ginkophyta
Cycadophyta
Gnetophyta
Coniferophyta
angiosperm divisions
Anthophyta
what kind of life cycle do gymnosperms have?
a sporic life cycle
are gymnosperms homo or heterosporous
heterosporous
what does it mean for something to be heterosprous?
separate male /female gametophytes
what do the microgametophytes of gymnosperms produce?
pollen
are the microgametophytes of gymnosperms free living?
yes
do gymnosperms have an antheridia?
no
why dont gymnosperms have an antheridia?
they produce sperm directly and have a pollen tube
is water required for fertilization of gymnosperms
no
does sperm have flaglla in gymnosperms?
no
function of a megagametophyte in a gymnosperm
it develops into part of a seed
is an archgonia present in a megagamtophyte?
yes, the eggs are produced there
Gymnosperm Megasporangium
- Surrounded by integument (1 or 2 layers)
- Reduction of megaspore mother cells (n=1).
- Meiosis produces 4 megaspores
- Unequal cytoplasmic partitioning
- One cell, mature megaspore
how pollination occurs in gymnosperms
•Pollen enters micropyle, may occur prior to megagametophytedevelopment.
•Mature Megagametophyteproduces archegonia (1-2)
•Pollen germinates to produce pollen tube, grows towards archegonium
.•Sperm swim or transported to egg.
how seed maturation occurs in gymnosperms
- Fertilization
- Embryo growth
- Dormancy
- Dispersal
Spores vs. Seeds
Spores: Haploid, single celled, develop into gametophytes
Seeds: Complex assemblages of tissue •Embyro(2N) •Nutritive tissue •megagametophyte(1N) gymnosperms •or endosperm (3N) angiosperms •integument (2N parental sporophyte)
true or false seed is not an egg.
true
Components of a seed
1) Embryonic sporophyte (multicellular 2N, product of fertilization).
2) Female gametophyte = Nutritive tissue.
3) Seed coat (hard layer that protects the embryo) derived from sporangium wall and integuments (parental 2N).
Advantages of Seeds over Spores
Nutrition
Rapid initial growth.Increased competitive ability compared to spores.
Advantages of Seeds over Spores
Dormancy
Delay development until conditions are favorable. Seed banks.
Advantages of Seeds over Spores
Permits life in harsh habitats
Reduction of adult lifespan (desert annuals).
Gymnosperm Pollen Development
Microspores develop into: -microgametophyte -mitosis -small 4 or 8 cells-pollen Formed in microsporangiate cones.
Microspores
develop into extremely reduced male gametophytes.
Pollen grain
immature male gametophyte (microgametophyte).This is the stage that pollen is shed (spring) and is wind-dispersed.
true or false, ginkgophyta are extinct in the wild
true
where can ginkgophyta be found today?
Preserved in temple gardens in China and Japan
physical structure of ginkgo
-Ovules produced singly-leaves produced on ‘short shoots’
is the sporophyte or gymnosperm generation of ginkgophyta
the sporophyte
are Ginkgophyta homo or heterosporous?
heterosporous
what is the male sporophyte of Ginkgophyta called?
microspoangiate
what is the female sporophyte og ginkgophyta called?
megasporangiate
is the sperm of Ginkgophyta motile?
yes
Ginkgo & Cycad Pollination
enter the megagametophyte where?
the micropyle
what kind of pollen tube do
Ginkgo & Cycad have?
Haustorial pollen tube.
how ginkgo and cycad are pollinated
- Pollen enter micropyle
- Haustorial pollen tube.
- Pollen tube grows into nucellus(megasporangium)
- Absorbs nutrition
- Pollen grain ruptures near archegonia.
- Sperm swim to egg in archegonium.
- Polyembryony: fertilization of multiple archegonia… usually only one embryo survives.
Gnetophyta
Group of unusual plants with varying growth form Possess standard set of seed plant characteristics Non-motile sperm
Coniferophyta wood contains only _____
tracheids, no vessels
Coniferophyta leaves are ___
needls
what are needles
highly modified megaphylls
are conifers hetero or homosporous?
heterosporous
is the sporophyte or gametophyte dominant in conifers?
Sporophyte dominant, most produce both microspores and megaspores on the same plant
is conifer sperm motile?
no
how are pollen and seeds dispersed in gymnosperms?
In gymnosperms, both pollen and seeds are usually wind-dispersed.
How are cycads pollinated?
Cycads are often insect pollinated (by weevils) and their fruits are fleshy and are eaten by animals.
the use of insects by cycads represents the first form of ______ for plant reproduction
animal-plant interaction
juniper berryies are dispersed how?
they are eaten by bird the seeds are dispersed in feces
