Closing the stomata can control water loss on a short-term
However, the stomata must be open at least part of the time to
allow CO2 entry.
Only epidermal cells containing chloroplasts
Have thicker cell walls on the inside and thinner c
Phloem-loading occurs at the source.
Carbohydrates (mostly sucrose) enter the sieve tubes in
the smallest veins at the source.
Sieve cells must be alive to use active transport to load
Water may be recirculated in xylem or lost through
What is the water potential of the surrounding solution?
What direction will the water flow?
What will be the effect on the plant cell?
What is the water potential of the plant cell?
Summary of Water Potential Problems
Remember that the pressure potentia
Transpiration provides the main force
Water potential regulates the movement of water through a
Water moves from the soil into the plant only if water potential
of the soil is greater than in the root.
Water in a plant moves along a yw gradie
Mycologists believe there may be as many as 1.5 million fungal
Single-celled or multicellular
Sexual or asexual
Specialized to extract
Some hyphae are continuous.
Others are ]
Both genomes transcribed
Sometimes many nuclei inte
A solution with a higher solute concentration has a more negative ys.
yw = yp + ys
The total water potential of a plant cell is the sum of its pressure
potential (yp) and solute potential (ys).
Represents the total potential energy of the water in the
Female gametes secrete pheromone to attract male
Giant mitochondria in its zoospores
Zygomycetes are incredibly diverse.
Include the common bread molds
A few human pathogens
Fusion of gametangia
Female pine cones form on the upper branches of the
Female cones usually take 2 or more seasons to mature.
During the first spring, pollen grains drift down between
A year later, female gametophyte matures
Pollen tube is digesting
Form intracellular associations with plant roots called
Cannot survive in absence of host plant
Glomeromycetes provide essential minerals
Plants provide carbohydrates
No evidence of sexual reproduction
Water Stress Responses
Many morphological adaptations allow plants to limit water loss
in drought conditions.
Loss of leaves deciduous plants
Covering leaves with cuticle and wooly trichomes
Reducing the number of stomata
Having stomata in pits