Transport in Plants Flashcards
How does water enter plants and what is its path?
enters roots, then moves to xylem, water rises through xylem, water sexist through stomata in leaves
How does water travel such great distance in plants?
some “pushing” from pressure of water entering roots, most of the force is “pulling” created by transpiration
What is xylem transport driven by?
transpiration (mostly) and root pressure
What is root pressure caused by?
continuous accumulation of ions in the roots (at night when transpiration is low)
What is guttation?
production of dew is water loss of water from leaves when root pressure is high
What are aquaporins?
speed up osmosis but do not change direction of water movement
What are essential for bulk transport of minerals?
tracheids and vessels
What 3 transport routes exist through cells?
apoplast route, symplast route, and transmembrane route
What is the apoplast route?
movement though the cell walls and space between cells, avoids membrane transport
What is the symplast route?
cytoplasm continuum between cells connected by plasmodesmata
What is the transmembrane route?
membrane transport between cells and across membranes of vacuoles within cells, permits greatest control
What is cavitation?
air bubble can break tensile strength of water column, gas-filled bubble can expand and block tracheid or vessel, damage can be minimized by anatomical adaptations
T/F The stomata must be open at least part of the time to allow carbon dioxide entry?
True
What are guard cells?
epidermal cells containing chloroplasts, have thicker cell walls inside and thinner cell walls elsewhere which cause to bulge and bow outward when they become turgid and cause stomata to open, turgor in guard cells results from active uptake of potassium chloride and malate (water enters osmotically)
When do transpiration rates increase?
temperature and wind velocity because water molecules evaporate more quickly
What are some ways that plants limit water loss during drought conditions?
dormancy, loss of leaves, covering leaves with cuticle and wooly trichomes, reducing number of stomata, having stomata in pits on leaf surface
What is flooding?
deplete available oxygen, leads to abnormal growth
What is a lenticel?
spongy area in the cork surfaces of stem, roots, and other plant parts that allow interchange of gases between internal tissues and the atmosphere through the periderm
What are pneumatophores?
long, spongy air-filled roots that emerge above the mud
What do sinks include?
growing root and stem tips as well as developing fruits
What is the purpose of having palisade mesophyll near the top of the leaf and having stomata on the bottom?
- loose palisade layer allows gas exchange to occur rapidly, stomata are on bottom to allow diffusion of air upwards 2. stomata can only differentiate bottom because UV radiation impedes their development, palisade layer helps shelter them 3. palisade cells control development of stomata on bottom of leaf through gravitational dispersal of hormones 4. tight-fitting palisade cells prevent water loss from hot surfaces of leaves, stomata allow gas exchange on bottom leaf, where it’s cooler and therefore has less water loss 5. stomata are on the top of the leaf while the palisade layer lines the bottom
