Lecture 24 -PLANTS- ASEXUAL REPRODUCTION-ALTERATION OF GENERATIONS-AND PLANT DEVELOPMENT - 11-20-07

Lecture 24 -PLANTS- ASEXUAL REPRODUCTION-ALTERATION OF GENERATIONS-AND PLANT DEVELOPMENT - 11-20-07

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Unformatted text preview: BIOLOGY 220 LECTURE #24 – PLANTS: ASEXUAL REPRODUCTION, ALTERNATION OF GENERATIONS, AND PLANT DEVELOPMENT PLANT REPRODUCTION – 2 Asexual reproduction • Faithful maintenance of genetic makeup – every individual in the population has the same genetic makeup o This means that all the offspring of an individual inherit any adaptations that the individual might have to a particular environment If a plant clonally reproduces, all the offspring will inherit any adaptations from the original plant. o You want to provision offspring with some resource so that offspring aren’t stealing your resources right away Decrease competition Tasty vegetables ASEXUAL REPRODUCTION – 3 • Bulbs: o This is an underground shoot that’s completely surrounded by tight fleshy leaves. o The rings on an onion are actually cross-sections of underground leaves. o Could wait underground until conditions become favorable for growth and reproduction ASEXUAL REPRODUCTION – 4 • Rhizomes: o Horizontal underground shoots o Dry hard, tightly wrapped leaves around the shoot. o Irises and ginger reproduce using rhizomes o Plant a node ASEXUAL REPRODUCTION – 5 • Tubers are swollen, fleshy underground stems • The “eyes” of a potato are buds for side-branches – areas that the stolen can grow out or the roots can grow out and you can grow a brand new plant from that. • Starchy, fleshy – great big food storage reserves that can be used for the plant to start growing • Every new plant needs some sort of food storage reserve before starting to photosynthesize and make their own food. • Potato could grow from ASEXUAL REPRODUCTION – 6 • The Runner o EXAMPLE: Strawberry plant o Plant itself produces long above-ground horizontal shoots and they grow out away from the plant and as they come in contact with a bare patch of soil a new plantlet starts to sprout and will grow directly from the runner o EXAMPLE: Virginia creeper ASEXUAL REPRODUCTION – 7 • Vegetative reproduction – Asexual reproduction or clonal reproduction – these terms mean the same thing o Most houseplants reproduce by vegetative reproduction (asexual reproduction). o Most plants that employ vegetative reproduction use a little bit of water to start development of the roots – then put the plant in soil. PLANT REPRODUCTION – 8 • Disadvantages of asexual reproduction o Low genetic diversity of population – if the environment changes at all, everyone dies because the organisms don’t have the genes to adapt to the environment o Species may go extinct • Many plants have sexual reproductive options in addition to asexual reproduction o Sexually reproduce or asexually reproduce when the situation is appropriate o Strawberries: Asexually reproduce: Runners Sexually reproduce: Fruit Usually do both • Alternation of generations PLANT REPRODUCTION – 9 Generalized Life Cycle – alternation of generations • Alternation of generations – A type of life cycle in plants...
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Lecture 24 -PLANTS- ASEXUAL REPRODUCTION-ALTERATION OF GENERATIONS-AND PLANT DEVELOPMENT - 11-20-07

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