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Published byAugusta Nelson Modified over 7 years ago
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. Embryo Food 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
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