Transpiration, Tropisms, Hormones in Plants

Transpiration, Tropisms, Hormones in Plants - hormones that...

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BSC 2011L
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Adhesion - water molecules momentarily will “stick” to the sides of xylem vessels Cohesion – water molecules cling together
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Transpiration – evaporation of water from leaves; continuous water column is pulled upward We will perform transpiration experiment today Environmental factors effecting transpiration: Temperature – as temp increases, so does transpiration Humidity – as humidity increases, transpiration decreases Wind – increased movement of air causes increase in transpiration
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In leaves, lower epidermis has openings called stomata Opening and closing of these regulated by guard cells When open, gas exchange and water evaporation occur The more stomata and the more they are open, the greater rate of transpiration
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Regulated by temperature, nutrients, and water availability Plants respond to environmental stimuli by utilizing
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Unformatted text preview: hormones that affect growth Positive tropism – growth of plant toward stimulus Negative tropism – growth of plant away from stiumlus Look at Fig 20.1 Negative gravitropism of stems Lay potted plant on its side and it will eventually bend upward Why does this happen? Gravity causes amyloplasts (plastids that store starch) to settle in lower part of cell This leads to increase in hormone AUXIN in lower part of stem Auxin causes cell elongation on lower part of stem bending it upward Bending of plants in response to light How does this happen? Auxin migrates from bright side of plant to dark side Auxin causes cells to become elongated on dark side, so that stem bends towards the light Altered growth patterns when seedling is grown without sunlight May assist seedling in reaching sunlight...
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This note was uploaded on 06/06/2011 for the course BSC 2011L taught by Professor Presley during the Spring '11 term at FAU.

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Transpiration, Tropisms, Hormones in Plants - hormones that...

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