Plants And Low Temperature Flashcards
What happens to the fluidity of cell membranes in low temperatures ?
The fluidity decreases due to membrane lipids solidifying. This causes the structures of proteins to deteriorate
What happens to photosynthesis and water uptake rates respiration rates in low temperatures ?
They all decrease
Why does dehydration occur at low temperatures ?
Dehydration occurs due to the freezing of water in the apoplast. This is the space between plant cells. Ice attracts liquid water meaning water is drawn out of the cell.
How does the proportion of fatty acids affect the fluidity of cell membranes ? Therefore what do temperate plants do in a drop in temperature ?
As the proportion of fatty acids increases the fluidity decreases.
Therefore temperate plants will decrease the amount of unsaturated fatty acids in their membrane to maintain fluidity when there is a drop in temp.
What temperature range do membranes of tropical plants solidify ?
0-10 degrees
What genes are expressed in temperate plants when there is a drop in temperature and what are the effects ?
Cold regulated genes (COR) are released causing an increase in unsaturated membrane lipids and an increase in cytoplasmic proteins, carbs and organic acids.
What proteins do COR genes encode ?
How are they activated ?
Anti- freeze proteins and enzymes for the biosynthesis of anthocyanin.
They are activated by CBF transcription factors. Resulting in an increase in cold tolerance.
How do antifreeze proteins work to decrease water loss ?
Antifreeze proteins are released into the apoplast when the temperature drops. They then bind to the axis’s of the ice crystals found there. This causes an inhibition of the growth of the ice crystals. They still form but cannot grow meaning no damage is caused. This in turn causes a drop in the amount of water being drawn out of the cell.
How do alpine plants adapt to the high sun environment ?
They produce pigments which absorb sunlight and reduce insolation to protect the photosynthetic pathway.
How does the freezing of gluttate in plants change with acclimation ?
The more a plant is acclimated to a low temperature then ice crystals in the gluttate in the apoplast will be much smaller, in turn causing significantly less damage.
What is latent heat and how is it used ?
Latent heat is heat produced by objects that are freezing. Plants use latent heat in internal freezing which utilises the heat produced by the freezing of water.
What are freezing organs ?
Plants have outer organs which they allow to freeze in turn causing the center of the plant to stay warme in the main dome.
