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51 Cards in this Set
- Front
- Back
Transpiration
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is the loss of water vapour from the leaves and stems of plants.
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Tissue of the leaf
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palisade mesophyll, upper Epidermis, xylem, phloem, guard cells, stoma, spongy mesophyll
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function of the palisade mesophyll
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- densely packed cylindrical cells with many chloroplasts
- main photosynthetic tissue |
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function of the upper Epidermis
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- continous layer of cells covered by a thick waxy cuticle
- prevents water loss |
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function of the xylem
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- transport of water
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function of the phloem
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- transport of products of photosynthesis
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function of the guard cells
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- control the amount of transpiration
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function of the Stoma
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- diffusion of O2 and CO2
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function of the spongy mesophyll
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- consists of loosely packed rounded cells with few chloroplasts
- main gas exchange surface |
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abscidic acid
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causes guard cells to close the stomata, produced when plants are suffering water stress
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Abiotic factors that have an effect on Transpiration (4)
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1. Light:
- guard cells close the stomata in darkness 2. Temperature: - as temperature rises the rate of transpiration rises 3. Humidity: - the lower the humidity the steeper the concentration Gradient and therefore the faster the rate of Transpiration 4. wind: - wind blows the saturated air away and therefore increases the rate of transpiration |
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xerophytes
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plants that are adapted to grow in very dry habitats
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adaptations of xerophytes
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- vertical stems to absorb sunlight early and late in the day but not at midday when light is most intense
- CAM physiology which involves opening stomata during the cool nights instead of in the intense heat of the day - spines instead of leaves to reduce the surface area for Transpiration - very tick waxycuticle covering the stem |
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increase surface area for absorption by ...
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branching roots and the growth of root hairs
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plants absorb ... by ... because...
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1. potassium, Phosphate, nitrate and other mineral ions from the soil
2. active transport 3. the concentration inside the roots is higher than in the soil |
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Three ways in which ions can move
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- diffusion of mineral Ions
- mass flow of water carrying ions, when water drains through the soil - into fungal hyphae, that grow around the plant roots in a mutualistic relationship, and the form the hyphae to the roots |
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structure of the stem
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support of the stem (3)
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- cells absorb water and high pressure develops inside the cell. This is cell turgor and it males the cell almost rigid.
- some cells develop thickened cellulose walls, which strengthen the plant - cell walls in xylem tissue are both thickened and lignified making them very strong |
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structure of xylem vessel
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- no plams a membranes so water can move in and out freely
- lumen of the xylem vessel is filled with sap - helical or ring-shaped thickenings of the cellulose wall --> support |
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transpiration stream
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when transpiration is occuring, water moves upwards from the roots to the leaves
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Evaporation
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heat from the environment provides energy for Evaporation of water from the cell walls of the spongy mesophyll in the leaves
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transpiration pull
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low pressure of suction is created inside xylem Kessels when water is pulled out
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cohesion and adhesion of water prevents ..
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the columns of water from breaking
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active translocation
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transport of sugars and amino acids by the phloem
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sources
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where sugars and amino acids are loaded in the phloem
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sinks
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where sugars and amino acids are unloaded from the phloem
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female gametes are contained in ..
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ovales in the ovaries of the flower
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male gametes are contained in ..
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pollen grains produced by the anthers
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zygote
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formed by the fusion of a male gamete with a female gamete inside the ovule. This process is called fertilization.
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pollination
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pollination is the Transfer of Pollen from an Panther to a stigma
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most plants use either ... or ... for pollination
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wind, animals
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seed disperal
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function of the fruit which are ovaries containing fertilized ovules
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structure of a flower
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external conditions for seed germination
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1. water must be available for rehydration
2. oxygen must be available for Aerobic cell respiration 3. suitable temperatures are needed, enzyme activity |
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structure of a seed
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metabolic events during germination
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1. absorption of water and rehydration of living cells in the seed
2. plant growth hormone calles gibberellin is produced by the cotyledons of the seed 3. stimulates the production of amylas which catalyzes the digestion og starch from the food stores of the seed 4. maltose is transported from the food stores to the growth regions of the seedling 5. maltose is converted into Glucose, which is either used as a source of enegry for cell respiration or to Synthesis cellulose |
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differences between mono- and dicotyledons
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M: leaf veins run parallel to each other
D: leaf Weins form a net-like Pattern M: vascular bundles are spread through the stem randomly D: vascular bundles are in a ring near the outside of the stem M. stamens and other organs in the flower are in multiples of 3 D: stamens and othe floral organs are in multiples of 4 M: unbranched roots D: branched roots |
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Bulbs
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-food storage
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stem tubers
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- food storage
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storage roots
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eg carrots
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tendrils
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- allow the plant to attach and grow upwards
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meristems
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regions where plants continue to divide and grow
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apical meristems
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meristems at the tip of the root and stems to elongate
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lateral meristems
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cambium in the vascular bundles, makes roots and stem thicker
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Is the night or the day length significant for short- day plants and long-day plants?
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night
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auxin
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plant Hormone, which acts as a growth Promoter
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phototrophism
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directional growth in response to the source of light (controlled by auxin)
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auxin efflux carriers
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pumps in the plasma membranes --> redistribute auxin in a tissue
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auxin receptor
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when auxin binds to it, transcription of specific genes is promoted
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phytochrome
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Pigment in leaves which measured the length of dark periods
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2 forms of phytochrome
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1. Pr:
inactive form, absorbs red light when it absorbs red light it is quickly converted into Pfr 2. Pfr: active form, absorbs far red light when it absorbs far red light it is rapidly converted to Pr In daylight (more red light than far red light): Pfr present In darkness: Pfr converts slowly into Pr |