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28 Cards in this Set
- Front
- Back
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Transpiration =?
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Water control
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- Stomata allow for gas exchange
- Stomata open during the day, when gasses are needed for photosynthesis - Stomata close at night - Reversed for desert plants to conserve water |
Water Control- Transpiration
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What creates tension in xylem?
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Transpiration
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Pulls cohesive column of water from roots to leaves
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Transpiration
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- High light levels
- High temperature - Low humidity - High air flow (wind) - High soil moisture content - More stomata on lower surface of leaf, to reduce water loss due to transpiration - Lower surface= Less heat and light from sun - Cuticle seal epidermis, further reducing water loss |
Factors that increase transpiration
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- Water still enters plant through roots when stomata are closed
- Root pressure builds - Gutation - Occurs when humidity and soil moisture are high, and transpiration rate low |
Water Control- gutation
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Water control?
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Gutation
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- Growth of new plant from small piece of an old plant
- Asexual |
Vegetative Reproduction
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- Epiphytes
- Some bromeliads are epiphytes - Epiphytic bromeliads have greatly reduced roots |
Modified Roots
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Plants that live attached to other plants?
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Epiphytes
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- Fine hair- like extensions of epidermis
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Trichomes
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- Fine hair- like extensions of epidermis
- Serve a variety of roles, depending on plant species - Reduce transpiration by decreasing air flow, and creating a dead space around the leaf - Reduce herbivory physically or chemically - Reflect sun in hot climates - Increase surface area for moisture absorption - Prevent frost forming on living tissue |
Trichomes
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- Trichomes wiith secretory cells
- Ex. sundew, herbs |
Glandular Trichomes
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- Old man of mount cactus
- Leaves have evolved into spines - Reduce water loss through transpiration - Less surface area - Protection from herbivory - Hairlike trichomes surrounding each spine - Further reduce transpiration by reducing airflow - Reflects Sunlight |
Modified Leaves
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- Rocky mimicry
- Leaves modified to look like rocks or pebbles - Reduce herbivory - Thick leaves store water |
Modified Leaves
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- Remove salt from xylem, keeping cellular concentration at healthy levels
- Allow plants to live in otherwise uninhabitable environments - Ex. Button wood, White mangrove |
Salt Glands
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- Color bracts look like petals, but are actually modified leaves
- Flowers are tiny, nested between bracts - Bracts attract pollinators - Ex. Bougainvillae and Poinsetta |
Modified Flowers
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- Red mangrove
- Seeds germinate while still on plant - Form propagles - Propagules drift in the ocean prior to becoming anchored and growing into a seed - Increased chance of survival in aquatic environment |
Modified Fruit
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Stores moisture?
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Mucilage (Aloe)
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Heals wounds, reduce herbivory?
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Latex
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Mucilage and latex?
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Secretory cells
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- Rapid response to touch or vibration?
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Thigmonasty
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- Thigmotrism
- Change in turgor pressure in specific cell causes leaves to move - Ex. mimosa |
Mastic Movements
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Venus fly trap
- 3-5 triggers on each side of leaf - Trap closes when a hair is touched twice in a row, or when two hairs are touched in rapid succession - Rapid increase in cell size along the outside edge of the hinge causes the leaf to close |
Nastic Movements
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- Etialation
- Seedling grown in darkness have long internodes: attempt to reach light - Lack of chlorophyll causes plant to be pale |
Light as Movement
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- Direction of growth is determines by light source
- The hormone auxin migrates away from light, causing cells along the dark side ot stem to elongate - Stems are positively phototrophic Roots are negatively phototrophic |
Phototropism
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- Can also be partially responsible for bending stem?
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Gravitropism
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- Apical dominance
- Apical bud produce auxin - promotes cell division in the bud - Inhibit growth in lateral buds to prevent competition for resources - Removing apical bud stops auxin production - Allows lateral buds to develop |
Lateral Bud Inhibition
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