Introduction to Plant Biology. First off: What is a plant? Domain? Kingdom? Categories?
What is a plant???
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Transcript of What is a plant???
What is a plant???
• Organism that is:• Multicellular• Eukaryote• Autotrophic• Has Cell wall
• Photosynthesizes
Plants evolved from Green Algae
Brainstorm with a neighbor: What are differences between algae
and plants?
Challenges from life in water to life on land
1. Obtain resources from BOTH air and soil
• Roots: below ground and absorb nutrients and water
• Shoots: above ground and convert sunlight and CO2 to energy
• Vascular system: moves water and nutrients between roots and shoots.
SHOOTS
ROOTS
Challenges from life in water to life on land
2. Remaining upright and not falling over
• Lignin: chemical that hardens the cell wall to give strength and support to plants.
Challenges from life in water to life on land
3. Maintaining Moisture
• Cuticle: Lipid, waxy covering that prevents water evaporation
• Stomata: Pores on underside of leaf that regulates water and gas exchange
– Guard cells: open and close the stomata
Hole = stomata
Cells around hole = guard cells
Challenges from life in water to life on land
4. Reproduction on land
• Need ways to prevent seeds from drying and ways to disperse
BRYOPHYTES
• Moss
• Lack lignin and are considered non vascular plants
• Require water to reproduce because gametes have flagella
Pteridophytes
• First group of plants to have vascular tissue (lignin)– Able to grow taller now
• Ferns, horse tails
• Reproduce through spores on underside of leaf and no longer dependent on water
Gymnosperms
• First seed bearing plants– Naked seeds because they are not surrounded by
fruit.
• Conifers and needle leaf trees
• Pollen cone– Male reproductive structure
• Pollen grains– Male gamete, adapted to dry environment and
transport through wind.
• Pine cone– Female reproductive structure
• Seeds– Plant embryo packaged with food supply inside a
protective coat.
ANGIOSPERM
• Flowering plants• Fruit: Ripened ovary used to protect seeds
and disperse them.
Parts of a Flower
• Petals– Brightly colored to
attract pollinators• Stamen– Male reproductive
structure– Anther: holds pollen
• Male gamete– Filament: holds up
anther.
Parts of a Flower• Carpel– Female reproductive
structure
– stigma: sticky to catch pollen
– Style: long tube that connects stigma and ovary
– Ovary: holds ovules (eggs)
How do Plants Reproduce?
• Pollination– Rely on animals to
transport pollen from male to female reproductive structure.
– Brightly colored petals attract pollinators
• Double Fertilization:–When pollen travels
down style it splits into 2 sperm cells• 1 fertilizes the
ovule to create seed• Other creates
food supply
Seed Dispersion
• Once pollination has occurred seeds need to spread to allow for new plant growth– Burrs can stick to animals and move – Fruit can be eaten and then the core thrown– Some seeds need to be completely digested in
order to grow.– Water currents and wind.
• Annuals:– Go through a complete
life cycle in one year.
Merigolds
Baby blue eyes basil
tomato
biennials
• Takes two years to complete the life cycle.
English daisy
Perennials
• Take several years to complete their life cycle.
agave
Baby’s breathCat tails
Roots
• Found underground– Anchor plant– Hold soil in place– Absorb water and
nutrients.
Types of Roots
• Fibrous Roots– SEVERAL THIN
BRANCHING ROOTS
Types of Roots
• Fibrous • Tap roots– Long root to anchor
plant– Several small horizontal
root hairs.
SHOOTS
• STEM– LOCATION OF LIGNIN– XYLEM AND PHLOEM
TO MOVE WATER AND NUTRIENTS THROUGH PLANT.
• Leaf– Location of
photosynthesis – 2 parts• Petiole• Blade
Types of Tissue in Plants
• Dermal Tissue–Acts as a
protective barrier for the plant.–Secretes the
cuticle.–Outer most layer
of tissue.
Vascular Tissue• Contains lignin to give support.
• XYLEM: transport water and nutrients from roots to shoots–Transpiration is
the evaporation of water through leaves that drives the process
Vascular Tissue• .
• PHLOEM: transports sugars due to diffusion (high concentration to low concentration).
Ground tissue
• Tissue found between dermal and vascular tissue.
• Most abundant tissue type
• Location of photosynthesis
Primary growth• Growth upwards and downwards in height.• Occurs at root caps and buds in plants.
Secondary growth• Growth in width outwards.• Adds new xylem and phloem.• Every 2 rings = 1 year of growth for tree rings.