Term
| Name the biome of most of australia according to annual precipitation and average temperature |
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Definition
| Semi-arid (<500mm of annual rainfall) |
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Term
| What plant systems dominate most of Australia? |
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Definition
Eucalyptus tropical woodland (savanna) 20%
Mulga woodland (25%)
Spinifex grassland (30%)
Forests (mostly eucalypt) (20%) |
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Term
| Why does clearing forests mean less rainfall? |
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Definition
| Evidence suggests a positive relationship between daily rainfall and cumulative exposure of passing air to vegetation (evapotranspiration) |
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Term
| Name and describe the two types of plants in relation to plant water relationships |
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Definition
Poikilohydric:Match cell water content to humidity, most lack central vacuoles, dried out and rehydrated (algae, lichen, mosses; only around 100 fern and angiosperm species)
Homoiohydric: Extensive root system requires water, large central vacuoles, loss of ability to dehydrate so will die when dehydrated (Most plants) |
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Term
| <1% water loss in homoihydric plants results in? |
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Definition
Cell growth ceases
Cell wall synthesis reduces
Protein synthesis decreases
Chlorophyll formation reduced
Enzyme levels reduced
Abscisic acid accumulation
Cytokinin reduced
Stomata close
CO2 assimilation reduced
Respiration reduced
Sugars accumulate |
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Term
| Describe the two transport cell systems in plants |
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Definition
Xylem: water moves from soil to atmosphere through hollow dead cells
Phloem: Photosyntheticall produced sugars and other molecules move from their source to sinks (non-photosynthetic tissues) throughout the phloem |
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Term
| How does water move through the xylem? |
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Definition
| Pulled by tension developed at evaporative sites. Psi = -15 to -100 MPa at evaporation site, in comparison to -0.2 MPa below ground, plants tap into this force to allow water to be drawn through its body. Also xylem tubes are very thin for capillary action/surface area |
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Term
| All solutions in a cell have a negative psi (MPa), true or false |
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Definition
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Term
| All solutions in a cell have a negative pressure (MPa), true or false |
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Definition
| False, pressure can be positive or negative (typical plant cell = 0.5-1.5) |
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Term
| What is the water potential (psi W)? |
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Definition
| The sum of the pressure potential (PsiP) and the osmotic potential (PsiTT) |
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Term
| Does water move towards higher or lower water potentials? |
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Definition
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Term
| A plant has a lower water potential than soil, allowing water to flow into the plant. True or false? |
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Definition
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Term
| How do plants adjust to changing water availability? |
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Definition
| Osmotic adjustment (uptake and/or production of solutes which create a more negative cell water potential) |
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Term
| What is the water potential of pure water at ambient atmospheric pressure? |
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Definition
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Term
| Describe the Soil-Plant-Air continuum in relation to water potential |
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Definition
| Root cells lower than soil so water moves in, leaves lower than roots so water moves up, air lower than leaves so water moves out |
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