Plants A survey of Kingdom Plantae. Characteristics of Plants n All Plants are Producers -...
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Transcript of Plants A survey of Kingdom Plantae. Characteristics of Plants n All Plants are Producers -...
Plants
A survey of Kingdom Plantae
Characteristics of Plants
All Plants are Producers - Photosynthetic
Plants are Multicellular Plant cells have cell walls Plants are Non Motile
Plant Evolution Plants are thought to have evolved from
Green Algae.
Modern Plants and Green Algae have the same type of chlorophyll, similar cell wall composition and both have starch as their food storing polysaccharide.
Green Algae
Green Algae may be unicellular or multicellular and primarily live in aquatic environments
Modern Plants however are adapted to life on land
Advantages of Life in Aquatic Environment
Constant source of water - no risk of desiccation
Nutrients are readily available Water provides support Water is a medium for the transport of
gametes They have a moist surface for gas
exchange
Life on Land
In order to survive on land plants must posses strategies or adaptations that compensate for the aforementioned advantages of life in water
Plant ClassificationP lan t C lass ifica tion
B ryop h teseg . M osses
S p ore p rod u c in gE g . F ern s
G ym n osp erm seg . C on ife rs
A n g iosp erm sF low erin g p lan ts
S eed P rod u c in g
Trach eop h ytes
P lan ts
Bryophytes
A common example of bryophytes are mosses
Bryophyte Characteristics
Have NO true roots, stems or leaves
Gas exchange occurs through small openings called stomates
Have NO Vascular tissue
Must live in moist areas Usually Small in size - 2cm. Are anchored to the ground by
structures called Rhizoids Gametophyte generation is dominant Each Gametophyte is a separate sex
Why are Bryophytes limited to Moist environments
Sperm have to swim to egg Only posses a thin cuticle so they are
prone to desiccation.
Why Bryophytes are Limited in Size.
With no vascular tissue there is no support for large sizes .
Also due to no vascular tissue materials are transported via diffusion…..this can only occur over a small area.
Reproduction In Bryophytes
Bryophytes undergo what is called an Alternation of Generations
An alternation between a haploid gametopyte generation and a diploid sporophyte generation.
Alternation of Generations in Bryophytes
See diagram on page 476
Tracheophytes
Tracheophytes are characterized by the presence of vascular tissue
Have “True” Roots Stems and leaves
There are two groups of tracheophytes:
sp ore p rod u c in g S eed p rod u c in g
Trach eop h ytes
What is Vascular Tissue?
Vascular tissue are parts of plants that are responsible for the transport of materials throughout the plant.
2 types of Vascular Tissue Xylem - transports water and minerals Phloem - transports “food”
Spore Producing Tracheophytes
An example of spore producing tracheophytes are Ferns
Characteristics of Spore Producing Tracheophytes
Vascular tissue
true roots,stems, and leaves
Thicker cuticle then Bryophytes
No seeds but spores
Sporophyte generation is dominant, Gametophyte generation is reduced
Gametophyte generation still dependent on water for reproduction
Both sex organs on one gametophyte
Alternation of Generations in Spore Producing Tracheophytes See page 477
Seed Producing Tracheophytes
G ym n osp erm s-C on e b earin g
A n g iosp erm s- F low erin g
S eed Trach eop h ytes
Gymnosperms and Angiosperms
These two groups of plants produce seeds.
Both have no need for water for reproduction and have true leaves, stems and roots. (needles are leaves).
In both the sporophyte is dominant (the plant is the sporophyte). The gametophytes are microscopic.
Gymnosperms Conifers are gymnosperms. There seeds are
in the female cones while pollen comes from the male cones.
They have advanced plant features (roots, leaves, stems) and usually restricted to harsh environments (cold). Why?
Thrive in cool climates, with poor soil, often found in moist seashore areas.
Some gymnosperms have leaves.
Life Cycle
They have a simple life cycle (page 479) and are often pollinated by wind.
Male gametophyte is the pollen grain Female gametophyte is the Ovule These gametophytes are contained
within cones.
Life Cycle
Male cones release millions of pollen grains.
If a pollen grain lands on the ovule of a female cone a pollen tube will form
sperm will travel down the tube and fertilize the egg.
Life Cycle
A covering forms around the zygote and the food supply to form a seed.
When seed ripen the cones will open seeds have papery wings and are
dispersed by the wind.
Angiosperms These are the most advanced plants
and have adapted to a wide variety of habitats (everywhere you see flowers, you see angiosperms).
Angiosperms These are the flowering plants: the
reproductive structures of plants are located within the flower.
Male and female sex organs are in close proximity and are often placed to take advantage of wind or insects.
Pollen moves from one place to another to ensure fertilization of eggs. (see life cycle on page 480).
Types of Flowers
Perfect Flowers Flowers that have both male and female
parts
Imperfect Flowers Flowers that have either male or female
parts
Fertilization of a Flower
When a pollen grain lands on a stigma a pollen tube forms
The pollen tube grows down through the style
The tube nucleus directs the growth of the pollen tube
The sperm nuclei enter the ovule
Fertilization of a Flower
One sperm nucleus fuses with the egg to form a zygote
The other fuses with the two polar nuclei to form a cell that becomes the endosperm (Food Source)
This is know as double fertilization
Seed Structure
After fertilization the ovule develops into a
seed.
Fruit After fertilization the ovary of the flower
enlarges forming the fruit. The seed is contained in the fruit
As the fruit ripens the flower parts fall away.
Reasons for the success of Angiosperms
1. Pollination is relatively easy (by wind, insects or self pollination)
2. Flowers tend to attract insects (for pollen or nectar
3. Seeds are protected by a seed coat (allowing seeds to pass undigested through most digestive tracts, then they grow in the free fertilizer)
Reasons for the success of Angiosperms
4. Fruits are attractive to animals who in turn help disperse seeds (above).
5. Seeds are able to suffer severe conditions such as fire, freezing, drought and then emerge when conditions are again suitable.
6. Plants themselves have adapted to a wide variety of habitats.
Types of Angiosperms
M on oco ts D ico ts
A n g iosp erm s
Monocots vs Dicots Vascular tissue Parallel veins in leaves vs Netted Veins in
leaves Seeds One Cotyledon vs Two Cotyledons Flowers petals in multiples of 3 vs petals in
multiples of 4 or 5
Monocots vs Dicots
Special Structures