Plant Transport Flashcards
What is osmosis?
water goes across a semi-permeable membrane to balance out solute concentration on the other side
What is water potential?
movement of water from higher water potential to an area of lower water potential
What is water potential measured in?
megapascals (MPa)
What is the equation for water potential?
Yw=Yp(pressure potential) +Ys (solute potential)
What is the solute potential for pure water?
0
What does a negative solute potential indicate?
that there’s more solute
What sign is pressure potential always?
positive
What happens when a beaker is open to the air?
there’s no pressure potential
Where does water move?
TOWARDS the more negative number
What is the xylem?
a unidirectional means of transport that move water up the plant from the roots to the leaves
Why does water in the roots get “pushed up”?
because since the roots have lots of water, theres positive pressure, and so water favors lower pressure, so it gets pushed up by the roots (pressure)
Why do the leaves on plants “pull water”?
because the leaves have lower pressure, so water gets pulled up to increase pressure in the leaves
What else, besides pressure, helps water get transported up?
cohesion and adhesion
What parts of the root does water and nutrients have to enter to get to the xylem or phloem?
epidermis and cortex
What is the function of the stomata?
opens and closes in order to allow for gas exchange (also releases water)
What are guard cells?
cells in the stomata that help the stomata open and close
What happens when guard cells are flaccid?
stomata closes
What happens when guard cells are turgid?
stomata opens
What are some reasons to close stomata and why?
-heat
-drought
because opening the stomata can cause the release of water
When does the stomata open?
during the daytime (for photosynthesis)
What happens when photosynthesis stops, to the stomata?
-glucose is pumped out of the chloroplasts and into the phloem
-water (from the guard cells) follows the glucose
What does ABA do?
-it binds to the turgid cells (after glucose is out)
-pumps oit ions
-water follows ions
so guard cells become flaccid, and stomata closes for the night
What does the phloem do?
distributes nutrients throughout the whole plant (unidirectional)
How does the phloem move, based on pressure?
-flows nutrients from high pressure places to low pressure places
What does high pressure places mean?
places within the plant that have lots of sugar and water
What is a source?
where nutrients are produced (leaves)
What is a sink?
where nutrients are needed (root)
