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Co-evolution: flowers & pollinators
How a bee sees a flower…insects see UV light = a bulls-eye to the nectar
Angiosperm: fruiting plants
Other fruits…
Seed & Plant embryo
• Seed offers…• protection for embryo
(new plant)• stored nutrients for
growth of new plant
seed coat
food for new plant
seed leaves
embryo(new plant)
Cotyledon (“seed” leaves) = first leaves of new plantCotyledon (“seed” leaves) = first leaves of new plant
Seed dispersal
• 4 types• Wind• Water• Animal• Explosive
Plant Hormones (how plant cells talk)• Hormone = chemical messages between cells;
regulate cellular processes• Formation of flowers, stems, leaves• Shedding of leaves• Formation/ripening of fruit• Growth – up or down• Sex of flower• Plant length of life; death
Plant hormone groups• Auxins
• Growth direction• Flower formation• Fruit set and growth• Formation of adventitious
roots (fibrous)
• Gibberellins• Stimulate cell division• Break seed dormancy; speed
germination
Plant hormone groups• Cytokins
• Aging and senescence (death)• Used to delay these processes
• Ethylene• Gaseous form only• Induces fruit ripening• Cause leaves to droop (epinasty)
and drop (abscission)• Produced in response to stress• Promotes senescence
Tropism • Directional movement responses that occur in response to a directional stimulus
• Phototropism = response to light• Thigmotropism = response to touch• Hydrotropism = response to water• Gravitropism/geotropism = response to gravity• Chemotropism = response to chemicals
• Tropisms can be positive or negative
• Positive = towards stimulus
• Negative = away from stimulus
Positive: with gravity
Negative: against gravity
Nastic Movement• Plant movement that occurs
in response to environment• Not dependent on the
direction of the stimulus
• Examples: Venus fly trap, mimosa leaf
Nastic movement VIDEO
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