Preventing freezing Flashcards
1
Q
What happens when cells freeze?
A
- membranes disrupted and they die
2
Q
How is the freezing point of the cytoplasm and vacuole lowered?
A
- cytoplasm and sap in the vacuoles contain solute which lower the freezing point
- sugars, polysaccharides, amino acids, and even proteins are produced which act as anti-freeze
- protect the cells from damage if they do freeze
3
Q
How are responses to freezing initiated?
A
- genes supressed and initiated
- in response to fall in temp and day length
4
Q
What controls stomatal closure?
A
the hormone ABA
5
Q
When is ABA released
A
released by leaf cells when under abiotic stress
6
Q
How are the roots involved with stomatal closure?
A
- provide an early warning of stress through ABA
- transported to leaves,
- binds to receptors on the plasma membrane of the stomatal guard cells
7
Q
What does ABA activate?
A
- changes in ionic concentrations
- reducing the water potential and the turgor of the cells
- as a result the guard cells close and water lost through transpirtation is readuced
