Transcript Plants - Chatt

Plants
Characteristics
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Eukaryotic.
Multicellular.
Photosynthetic.
Cell walls contain
cellulose.
• Develop from embryos
protected by parental
tissue.
Earliest Ancestor
• The earliest land plants may have evolved
from algal-like organisms.
Generalized Life Cycle
• Alternation of generations.
– Gametophyte generation (n).
– Sporophyte generation (2n).
Plant Types
• Non-Vascular (bryophytes)
• Vascular (tracheophytes)
– Spore-producing
– Seed-producing
Non-Vascular Plants
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Includes mosses, liverworts and hornworts.
Lack true roots, stems, leaves and vascular tissue.
Grow in moist environments.
Only several centimeters in height.
Sexual (spores) or asexual (vegetative
propagation).
Vascular Plants
• Conducting tissue.
– Xylem & phloem.
• Allowed greater
heights in plants.
Spore-Producing Vascular Plants
• Includes club mosses and horsetails.
– Primarily grow in marshes and along edges of
streams.
• Includes ferns.
– Primarily grow in shady, wet environments.
Reproduction in Non-Vascular &
Spore-Producing Vascular Plants
Both require water for the sperm to swim
from antheridium to archegonium to
fertilize egg.
Fern sperm
Seed-Producing Vascular Plants
• Most successful plants on Earth.
– Due to specialized leaves, stems and roots.
• Sexual reproduction occurs via pollination.
– Does not require water.
– Seeds withstand desiccation.
• Includes:
– Gymnosperms.
– Angiosperms.
Gymnosperms
• Reproductive structures.
– Pollen cones (male).
– Seed cones (female).
• Pollen dispersed by wind.
• Pollen produces sperm
when contact is made with
seed cone.
• Sperm fertilizes ovules.
• Zygotes grow into seeds.
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Gymnosperms
Conifers are the most numerous.
Conifers
• Referred to as “softwood”.
• Accounts for 50% of
Ontario’s forests.
• Canada supplies 20% of
world’s softwood.
Angiosperms
• Known as the flowering plants.
• Most successful plants on Earth.
– Well-protected seeds.
– Variety of seed dispersal mechanisms.
• Wind, water or animals.
Angiosperms
• Reproduction:
– Ovum fertilized by sperm (from pollen).
– Zygote develops into an embryo contained in
a seed.
– Seeds are enclosed in a fruit.
– Seeds must be
released from fruit in
order to germinate.
Angiosperms
Self-pollination
Angiosperms
Cross-pollination
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