Transport in plants Flashcards
How do root hairs absorb water from soil?
soil has high water potential while cell sap in root hair vacuole has low water potential due to dissolved substances. the water moves down the concentration gradient through osmosis from soil to root hair. Root hair will now have a higher water potential than neighbor cortex cells.
how do root hairs absorb mineral salts from soil?
Cell sap in root hair vacuole have a higher concentration of nutrients than the concentration of mineral salts in the soil. The mineral salts will be actively absorbed and energy will be needed.
What is major apoplast pathway?
This is diffusion along cell walls and intracellular spaces. The intracellular spaces closer to stele will have lower water potential than that closer to the root hair. water will move down concentration gradient. faster
what is minor vacuolar pathway?
Water move by osmosis from one cell vacuole to next. cells closer to root hair will have higher water potential than cells closer to stele. water will move down concentration gradient. slower
what is symplast pathway?
Water moves through the plasmodesmata and cytoplasm of one cell to next down concentration gradient.
How does water go from the endodermis to xylem?
from endodermis Caspary bands water will move through passage cells and through pericycle to xylem in root.
What is root pressure?
is the upward force of water due to the influx of water from soil that is absorbed by root hair.
what is capillarity?
is the ability of water to move spontaneously up narrow tubes such as xylem vessels and tracheid’s due to cohesion and adhesion forces of water.
what is transpiration?
Is water lost in the form of water vapor through the aerial parts of plant.
what is transpirational pull?
due to transpiration the air chamber inside the stoma will have a low water potential while the xylem will have a high water potential. the water down water potential gradient which means it will move up the xylem against gravity by the help of capillarity. there is an unbroken column and water will be drawn from root system.
How does humidity affect transpiration?
high humidity means more water vapor in atmosphere. the difference in water vapor between outside and inside leaf is less. smaller gradient means less transpiration.
high humidity=low transpiration
low humidity=high transpiration
How does light affect transpiration?
When there is light there will be photosynthesis which will increase rate of transpiration
high light= high transpiration
low light=low transpiration
How does temperature affect transpiration?
temperature increase and water molecules will have more kinetic energy and will move faster meaning increased transpiration.
high temp=high transpiration
low temp=low transpiration
How does wind affect transpiration?
wind will blow off water vapor from surface of leaf. difference of water vapor within and outside leaf will increase. increased transpiration
high wind= high transpiration
low wind=low transpiration
what are structural modifications of plants to limit transpiration?(4)
sunken stoma- region sunken will trap moisture and less difference in water vapor inside and outside leaf stomata
thick cuticle- prevent water loss
hair on leaves- trap water particles which can reduce diff of water inside and outside leaf
shape/size and arrangement of leaves- leaves can overlap or be vertical to reduce exposure to environment
