Exam 4 - Osmoregulation in Plants Flashcards
What is turgor pressure?
pressure exerted by the protoplast against the cell wall
How does water cross membranes?
through aquaporins
What are the characteristics of aquaporins?
- integral membrane proteins that form water-selective channels across the membrane
- account for observed higher rates of water movement than diffusion alone
What are the advantages of aquatic life?
- buoyancy
- abundant water
- moderate temperatures
- filtered light
What are the obstacles of living on land?
- no buoyancy
- scarce water
- extreme temperatures
- excess light, including UV
What are a plant’s responses to water deficit?
- decreased photosynthesis
- decreased stomatal aperture
- decreased shoot meristem and leaf growth
- decreased water uptake
- increased solute accumulation
- increased root growth
What is osmotic adjustment?
-biochemical mechanism that helps plants acclimate to dry or saline/salty soil
What is the relationship between solute/osmotic potential and molarity?
directly proportional relationship
What does the addition of solute do to solute potential?
decreases solute potential
What is pressure potential?
the physical pressure on a solution
What does osmotic adjustment result from?
a net increase in the number of solute particles in the plant cell
How does osmotic adjustment work?
- solutes are added to the cell, decreasing solute potential
- osmotic adjustment drives water potential in the root lower than in the soil
- water moves down a potential gradient from the soil into the plant
What are halophytes?
salt-tolerant plants that are genetically adapted to saline conditions
What are glycophytes?
less salt-tolerant plants that are not adapted to saline conditions
How do saline environments contribute to cytotoxicity?
cystolic Na+ increases, and the ions can become toxic by denaturing proteins and destabilizing membranes
