Term
| 4 main problems caused to plants by low temperatures? |
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Definition
Decreased membrane fluidity, flexibility and elasticity
Dehydration as water can freeze in the apoplast
Decreased metabolic rate because of a decrease in liquid water.
Physical damage from shards of ice – mostly fatal |
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Term
| Knock on effects of decreased membrane fluidity, flexibility and elasticity? |
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Definition
This in turn causes a decrease in photosynthesis and respiration
Decrease in water uptake and ion uptake |
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Term
| What are the consequences of water freezing in the apoplast? |
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Definition
Freezes first due to fewer solutes
Draws water out of the cell |
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Term
| What are the main problems of water freezing in the apoplast |
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Definition
Freezes first due to fewer solutes
Draws water out of the cell |
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Term
| What affects might dehydration have on a plant? |
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Definition
Decreased metabolic rate
Change in structure of proteins |
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Term
| What will ice do to cells? |
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Definition
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Term
| How do maintain a fluid membrane? |
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Definition
Increase unsaturated fats
Acyle desatureases |
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Term
| What is the effect of expressing COR genes? |
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Definition
1. An increase in unsaturated membrane lipids
i. Keep membrane fluid
2. An increase in cytoplasmic proteins, Carbohydrates and organic acids
i. Decrease the osmotic potential of the cytoplasm |
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Term
| What do cor genes code for? |
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Definition
| Antifreeze proteins and enzymes for Biosynthesis of anthocyanin |
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Term
| What is the role of antifreeze proteins |
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Definition
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Term
| What is the role of antifreeze proteins |
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Definition
| Prevent ice crystal growth along the a-axis |
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Term
| How are COR genes activated |
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Definition
| core binding factors (transcription factor) (CBFs) |
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Term
| Where do core binding factors bind too? |
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Definition
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Term
| Does ice have a high or low water potential |
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Definition
| Ice has a low water potential |
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Term
| What physical features do alpine plants have that enable them to cope with the extremely low temperatures? |
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Definition
1. They use pigments to decrease insolation and protect photosynthesis (this is a response to free radicals caused by excess light)
i. Plants close stomata to save water
ii. No C02
iii. Freezing cold
iv. High light conditions
2. Most are cushion or cushion-Like plants with altered heat-balance (Headgeahof boom & dianthus)
3. Hemispherical and low to the ground
o SA/V ratio very low
o Insulating core
o Low to ground get the heat from the ground from solar energy
4. Many have controlled internal freezing which utilises latent heat
i. When liquid water goes to ice it’s a low energy state.
ii. Heat is given out when water goes to ice
5. Many have life history adjustments to suit the weather
i. Short periods of growth at optimum time |
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Term
| In the tropic what evolutionary startergies have plants developed inorder to regulate leaf temperature |
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Definition
Evaporative cooling is main method of losing temperature
Large Surface area to volume ratio
Many plants from the wet tropics have large, deep Green leaves
Boundary layer |
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Term
| Name the two types of 'specific transcription factor' that are particularly prevalent in cacti. |
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Definition
HS70
HS100
recognise damaged proteins and refold them |
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Term
| What mechanism have savannah plants evolved to maximise heat loss |
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Definition
For savannah plants, small pinnate leaf structures can aid in heat loss due to minimal boundary layer; creates turbulence which aids convection and conduction.
Large surface area to volume ratio |
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Term
| Which 3 carotenoids are produced in nonphotochemical quenching as part of the Xanthophyll cycle. |
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Definition
| violacanthin, Antheraxanthin and zeaxanthin |
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Term
| Which proteins trigger gene expression of heat shock proteins |
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Definition
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Term
| Main adaptations of savannah plant |
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Definition
Small pinnate leafs to help produce convection currents called eddy currents that draw heat away
small boundary layer as evapotranspiration isn't an option
Heat shock proteins. |
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Term
| adaptations of cacti to desert conditions |
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Definition
Shape produces turbulence to draw heat away with convection currents.
Low albedo
Sunken stomata that are surrounded by hairs to trap moisture.
spines are not only a defence mechanism they also draw heat from the core of the plant |
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Term
| name the 'steriotypical' cacti that is found in the mohabi desert |
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Definition
| Carnegiea gigantea (Saguaro Cacti) |
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