Transcript Immergence of Seed plants

Chapter 29 and 30: Plants
Objectives
-Understand that land plants evolved from green algae
-Mosses and other nonvascular plants have life cycles dominated by gametophytes
-Ferns and other seedless vascular plants were the first plants to grow tall
-Seeds and pollen grains are the key to success for land plants
-Gymnosperms bear “naked” seeds (cones)
-Reproductive adaptations of angiosperms include flowers and fruit
Morphological and Molecular data suggests land
plants evolved from green algae
(Charophytes)
Morphological
1.
Rossete shaped cellulose synthesizing
proteins in plasma membrane
2.
Peroxisome enzymes that help minimize loss
of organic products of metabolism from
photorespiration
3.
Flagellated sperm
4.
Formation of a phragmoplast during cell
division
Genetic Sampling also indicates similarities
2. Production
of protective
spores
Adaptations or
derived
characteristics that
allowed plants to
move to land.
4. Use of an
Apical
meristem for
elongation
1. Alternation of Generations
-Has a multicelluar haploid and
diploid organisms
-Plants are called embryophtes
due to the embryonic
activity in the female
gametophyte
- Analogous to mammals
3. Multicellular
Gametangia (1n)
Current Understanding of plant evolution
Bryophyte refers to all Nonvascular plants
-Gametophytes are longer and larger then Sporophyte
Horwort
Liverwort
Mosses
Seedless Vascular Plants
-Sporophyte dominant
-Contain Xylem, which brings water and minerals up from the roots
** Allows for strength in stem = growing tall
-Contain Phloem for transport of organic compounds
Sporophylls
-Modified leaves that contain Sporangia
-Homospores = one type of spore
-Heterospore = male (microspore)
and female spore (megaspore)
Leaves divided into
1.
Microphylls (smalll)
2.
Megaphylls (large extensive leaves)
Seedless
Vascular Plants
The importance and
evolutionary significance
of seeds as a derived
characteristic
1. 2n Embryo with its food
supply
2.
Means the embryo
can survive away
from mother plant
3.
Analogous to a
detachable woman’s
womb
4.
Dispersed in a variety
of ways
5.
Contributions to
human society
Hunter/Gatherer
to
Settlers using agriculture
Immergence
of Seed
plants
1.
Reduced Gametophyte stage –Allows for protection of the gametophytes within
the sporangia of the sporophyte = great success in seeded plants
2.
Contain heterospores (Male and Female)
3.
Seeds have advantages over spores (More protection, Food source, Can
remain dormant longer, Stored food can help in germination)
Development of seeds and pollination
1.
Female (Megasporangium) is covered
by a thin layer called integument
2.
Megasporangium undergoes Meiosis
and produces a Megaspore
3.
Pollen is produced in a mircospore
4.
Pollen doesn’t need water to swim in
like Flagellated sperm of seedless
plants (Wind or hitch hike)
1.
Female Gametophyte grows
2.
Male Gametophyte is in the pollen grain
3.
Pollination occurs (Pollen (1n) enters through an
opening of the integument and fertilizes the egg
4.
After fertilization the integument turnes into the seed
coat
5.
Embryo or new sporophyte begins to form
Gymnosperms
- Naked seeds (No Fruit)
-Four Gymnosperm Phyla
1.
Ginkgophyta
2.
Coniferophyta
3.
Cycadophyta
4.
Gnetophyta
Pollination occurs when pollen attaches
to the Megaspore and germinates
forming a pollen tube (digests its way
through the Megasporangium)
Conifers have
both pollen and
ovulate cones
While pollen tube
extends the
Megaspore undergoes
meiosis
Microspores produce
pollen grains that
contain the
gametophyte
Usually takes
about a year from
pollination to seed
and only one
embryo usually
survies
Stamen produce
microspores which
turn in to pollen
Carpel produces
megaspores
Angiosperms are
flowering plants
Fruits
-Fruits are the ovary with the fertilized
seed inside
-Protect and aid in dispersion
Some flowers self
pollinate while
most have
mechanisms to
cross pollinate
Double fertilization
produces
endosperm or
nutrients
-Possible reason is
to synchronize
development of food
sources and seed
4 megaspores are
formed with one
surviving
Monocots
Eudicots
Basil Angiosperms
Magnoliids