What is a plant? Unit 7 Chapter 20. Plant characteristics Eukaryotic Multicellular Autotroph: food...
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Transcript of What is a plant? Unit 7 Chapter 20. Plant characteristics Eukaryotic Multicellular Autotroph: food...
What is a plant?
Unit 7
Chapter 20
Plant characteristics
Eukaryotic Multicellular Autotroph: food made through photosynthesis Cell walls made of cellulose Cuticle: waxy covering on plant body May have originated from green algae
Evidence for algal ancestry
Cellulose cell walls in algae and plants
Same types of chlorophyll for photosynthesis and stores sugar as starch
Fossil record dated 440 MYO showed plants without leaves
Adaptations to living on land
Algae are mostly found in water as they have no adaptations to prevent drying out on land.
Plants have structures that enable life on land. Roots Cuticle and waxy coats Protection for gametes
(sperm and egg)
Leaves
Plant organ that photosynthesizes
May occur in other plant parts with chlorophyll (ex: stems of cactus)
Roots
Absorbs water and minerals from soil
Helps to anchor plants to ground
May store sugar reserves (taproot)
Stem
Transports water and minerals from roots to branches and leaves
Transports sugar from leaves to storage organs
May store sugars and water (ex: sugar cane, cactus)
Xylem and phloem: specialized cells that transport sugar and water
Xylem and phloem make up vascular tissue
Supports plant life away from water source
Phloem: sugar
Xylem: water and minerals
Nonvascular plants: plants without xylem and phloem Mosses, hornworts, liverworts
Nonvascular plants
Simple Few cell layers thick Doesn’t need vascular tissue to transport
water and sugar because simple diffusion suffices
Reproduction without water
Algae require water to transport sperm to egg for fertilization.
Land plants store food with embryo within a protective coat. This forms the seed.
Seeds are easily dispersed and protected from the environment.
EmbryoFood supply
Seed coat
Seedless plants
Sperm requires small water film to get to the egg.
Spores are formed instead of seeds.
Alternation of generation: plant life cycle
Gametophyte (n)
Sporophyte (2n)
Spores (n)
Meiosis
Male gamete (n)
Female gamete (n)
Fertilization
Mitosis and cell division
Survey of Plant Kingdom
Liverworts: nonvascular, seedless
Hornworts: nonvascular, seedless
Mosses: nonvascular, seedless
Whisk ferns: vascular, seedless
Club mosses: vascular, seedless
Ancient club mosses form the coal reserves found today
Horsetails: vascular, seedless
Ferns: vascular, seedless
Fronds: fern leaves with spores that grow underneath
Cycads: exposed seed, vascular
Ginkgos: exposed seed, vascular
Welwitschia: exposed seed, vascular
Conifers: exposed seed, vascular, bearing cones
Flowering plants: seeds within fruits, vascular