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Vascular Plants. Moving to Land. Overtime, 500 millions of years ago, plants on Earth evolved from aquatic to terrestrial environments What are some problems to overcome? Material transport Structure/support Desiccation Gas exchange. Benefits to moving to land.
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Moving to Land • Overtime, 500 millions of years ago, plants on Earth evolved from aquatic to terrestrial environments • What are some problems to overcome? • Material transport • Structure/support • Desiccation • Gas exchange
Benefits to moving to land • easier access to sunlight for photosynthesis, • continuous free movement of carbon dioxide and oxygen
Vascular Plant Organs Roots, stems and leaves
Vascular Plant Organs • Roots – Absorb water and dissolved nutrients from soil • Anchor plants – in the soil and prevent them from being knocked down by wind • Storage – site for food storage
Vascular Plant Organs • Stems – Support - hold leaves up towards the sun for optimal exposure for photosynthesis • Transport – between roots and leaves (via vascular tissue, phloem and xylem • Storage – site for food storage
Vascular Plant Organ • Leaves – Photosynthesis and Cellular respiration • Formulas???? • Modified to reduce transpiration • Cuticle and pores
Vascular Tissues • http://www.harcourtschool.com/activity/vascular/vascular.html
Vascular Plant Tissues • XYLEM– Carries water and dissolved nutrients from the soil, from the roots, into the stem and into the leaves. • It forms a continuous set of tubes that stretch from the roots to the leaves
Vascular Plant Tissue • PHLOEM– Distributes food made in the leaves throughout the plant. • The glucose produced by photosynthesisin the leaves, moves down towards the roots.
Questions • The direction of glucose transport can be reversed in situations when the glucose levels in the roots are greater than in the leaves. • In which situations might this occur?
Vascular Plants • 10 phyla • Includes:1) seedless vascular plants (ie. ferns) 2) plants with unprotected seeds (ie. Cone-bearing plants) 3) flowering plants
Similarities with mosses • 1) free-living gametophyte • 2) no seeds • 3) mobile sperm that require water for fertilization
Differences from mosses • 1) a vascular system which transports water, nutrients and photosynthetic products around the plant, • 2) sporophytes as the dominant life stage • 3) stomata
Fern • Most diverse group of plants • Most abundant after flowering plants • Alternation of generation between gametophyte (haploid) and sporophyte (diploid)
Fern Life Cycle • http://trc.ucdavis.edu/biosci10v/bis10v/media/ch15/fern_life_cycle_v2.html • Takes notes from fig 10.7
Fern Life Cycle -gametophyte (n) makes gametes sperm (n) and egg (n) -gametes fuse when mature, fertilization -zygote (2n) develops attached to gametophyte (n) -zygote becomes spore-bearing sporophytes (2n) -spores (n) disperse and develop into gametophytes(n)
Fern Sporophyte -large leaves are called fronds -fronds contain spores on the underside, contained in a sac called sporangia -sporangia cluster together to form a sori
Young sporophyte growing out of a gametophyte Sori containing clusters of sporangia Grape-looking structures are individual sporangium