Bio - 8.1, 8.2, 8.3, 8.4 Flashcards
xylem - transport structure
- leaf = outside
- stem & root = inside
xylem
- made of many dead cells
- has thick walls stiffened with lignin (support)
- hollow lumen
- one way flow
- transports water & minerals
phloem
- made of living cells
- no lignin
- has end walls with sieve plates
- two way flow
- transports surcose & a.a
transpiration
- process by which moisture is carried through plants from roots to the stomata (where it changes to vapor and is released to the atmosphere)
- basically EVAPORATION of water from plant leaves
5 factors that affect transpiration
- wind speed
- INCREASES = INCREASES transpiration rate - humidity
- INCREASES = DECREASES transpiration rate - light intensity
- INCREASES = INCREASES transpiration rate - temperature
- INCREASES = INCREASES transpiration rate - water supply
- DECREASES = DECREASES transpiration rate
transpiration process / stream
parts : root => stem => leaf
process : water goes up => evaporates from leaves => pulls more water up
*high to low con
capillary action
- how water moves UP through narrow tubes (like xylem) without needing a plant
cohesion - capillary action
- water molecules stick to each other
- water chain
- after water is evaporated it needs to be replaced
adhesion - capillary action
- sticks to walls
- prevents from falling back down
basic process of transpiration
roots (osmosis into root hairs) => xylem (cohesion & adhesion) => leaf (evaporation from stomata)
how have plants adapted
- root hair cells = high SA
- hollow xylem = easy pathway for water flow
- many air spaces = increases rate of evaporation
- stomata = opens to allow transpiration
measuring tool for transpiration ?
potometer
translocation - definition
- movement of organic solutes (esp sucrose and amino acids)
- via phloem
- source to sink
phloem - translocation
- sucrose & amino acids
- source = leaf
- sink = roots / flowers / fruit
source vs sink
- source (produces) = where sucrose is made (leaf)
- sink (receives) = where sucrose is stored / used (roots)
tropism - definition
growth in response to a stimulus
positive tropism - definition
towards the stimulus
negative tropism - definition
away from stimulus
phototropism - definition
growth in direction of light
geotropism - definition
growth in direction of gravity
hydrotropism - definition
growth in direction of water
auxin - definition
a plant hormone that controls growth by promoting cell elongation
auxin
- made of tips of shoots and roots
- can diffuse to other parts of shoots and roots
- change the rate of elongation in plant cells
*cells in shoot elongate more
*cells in roots inhibit elongation
roots and flowers changing substances
roots : sucrose => starch (to store)
flowers : sucrose => fructose (to attract animals)
translocation during harsh conditions
- plants do not photosynthesize during super hot / cold weather
- sinks will become sources => convert back to sucrose => translocate to other parts of the plant
(e.g) roots convert starch to sucrose
