Presentation on theme: "Kingdom Plantae Chapters 30 - 33. How have modern plants evolved? Had to develop adaptations for life on land Evolved from plantlike protists – green."— Presentation transcript:
How have modern plants evolved? Had to develop adaptations for life on land Evolved from plantlike protists – green algae First plants were similar to today’s mosses – dependent on water
3 Plant Adaptations to Land Problems: Need minerals Gravity Increase in Height for Light Adaptations for Drier environment Reproduction Solutions: Roots absorb H 2 O & minerals Lignin & cellulose in cell walls Vascular Transport System Waxy cuticle & stomata with guard cells Pollen containing sperm
What are characteristics of plants? Multicellular Eukaryotic cellulose cell walls autotrophic (photosynthetic) Chlorophylls a and b in thylakoid membranes Store reserve food as amylose (starch)
What is the plant life cycle? Alternation of generations: – Sporophyte – 2n – Diploid – produce haploid spores by meiosis – Gametophyte - (1n) – haploid undergoes mitosis to produce eggs and sperm – the eggs and sperm (gametes) – Zygote - merge to grow into a 2n sporophyte (cycle continues)
6 Alternation of Generations 2n Sporophyte 2n gametophyte 1n pollen Ovary with 1n ovules (eggs) 2n seed with plant embryo Sporophyte Gametophyte
What do plants need to survive? Sunlight - energy of sun captured by chlorophyll and used to join CO 2 and H 2 O to form glucose (C 6 H 12 O 6 ); plants need broad leaves to maximize light absorption Water and minerals - roots to absorb these Gas Exchange – stomata in leaves Movement of water and nutrients – Most plants have tubes – phloem (nutrients down) and xylem (water up) – Some small plants use diffusion
8 Nonvascular Plants Do not have vascular tissue for support or conduction of materials Called Bryophytes Require a constantly moist environment Moss Gametophytes & Sporophytes Sporophyte stage Gametophyte Stage
9 Nonvascular Plants Plants can’t grow as tall Cells must be in direct contact with moisture Materials move by diffusion cell-to-cell Sperm must swim to egg through water droplets
10 Vascular System Xylem tissue carries water and minerals upward from the roots Phloem tissue carries sugars made by photosynthesis from the leaves to where they will be stored or used Sap is the fluid carried inside the xylem or phloem
What are the four main groups of plants? Mosses – Bryophytes (15,600 species) Ferns – Pterophytes (11,000 species) Gymnosperms - Cone-bearing Plants (760 species) Angiosperms - Flowering Plants (245,000 species)
What are the characteristics of the mosses? BRYOPHYTA Low-growing, live in moist areas, depend on water for reproduction No true stems, leaves, or roots (rhizoids, instead), no seeds, non-vascular
What are monocots? Single cotyledon – number of seed leaves parallel veins (venation), floral parts in multiples of 3, fibrous roots, scattered vascular bundles
What are dicots? Two cotyledons, branched veins (net venation), floral parts in multiples of 4-5, taproot, ring of vascular bundles.
What are the structures of a plant? Dermal Tissue – thick waxy layer, sometimes fuzzy, roots have hairs (water absorption), stomata for gas exchange Stems – vascular tissue – phloem and xylem – Monocot and dicot differences: In dicots – cambium forms xylem to the inside and phloem to the outside ( pith in the middle) – Wood is layers of xylem
How does water transport work in plants? Root pressure – active transport and movement of water into roots Capillary action – water molecules attracted to one another by cohesion and to walls of xylem by adhesion Transpiration – evaporation from surface of leaves
How do hormones affect plant growth? Chemical messengers that respond to the environment Growth regulators b/c they stimulate or inhibit growth
What are tropisms? Plant movement based on environmental stimulus (page 654) – Gravitropism – response to gravity – Phototropism – response to light direction – Chemotropism – response to chemicals – Thigmotropism – response to touch
What is photoperiodism? plant response to length of day and night Can affect flowering times, etc.
How do we get maple syrup? (fyi only) In 1663, English chemist Robert Boyle told associates in Europe, “There is in some parts of New England a kind of tree whose juice that weeps out its incision, if it is permitted slowly to exhale away the superfluous moisture, doth congeal into a sweet and saccharin substance and the like was confirmed to me by the agent of the great and populace colony of Massachusetts. Tapping is done in late winter (cold nights and warmer days). Enzymes begin to break the starch into sugar. It will flow during the day. Tapping is done into the phloem.