plant transport Flashcards
(9 cards)
what are the 3 parts of transport in the xylem?
root pressure, capillary action, transpiration
describe root pressure
when water and minerals are absorbed via soil
the force of water entering the root and pushing its way into cells creates pressure
Adhesion, explain (xylem)
the force attraction between water molecules and the molecules that make up the inside surface of the xylem vessels
cohesion, explain
forces of attraction between the water molecules themselves which help to pull the molecules up the narrow xylem vessel. this is called cohesion
capillary action is described as
the combination of cohesion and adhesion forces that allows water to flow in narrow spaces in opposition to gravitational forces.
describe transpiration and explain
the loss of water vapour by evaporation from the surface of a plant via the stomata
when stomata are open a continuous stream of water rises through the plant
the combination of evaporation due to energy from the sun, capillary action and root pressure creates the continuous stream
factors affecting transpiration
Light, Humidity, Wind, Temperature
what is translocation
transporting dissolved substances like sucrose from the site of photosynthesis, mostly leaves, to stems and roots
comparing transpiration and translocation
Site:
- transpiration, Xylem
- translocation, Phloem
Material:
- transpiration, water, dissolved mineral nutrients
- translocation, products of photosynthesis,
Direction
- transpiration, one way from roots to leaves
- translocation, both ways from leaves to stem or roots
energy requirements
- transpiration, passive
- translocation, active
mechanism
- transpiration: root pressure, capillary action, transpiration
- translocation: active transport of sugars into phloem sieve tubes, which causes an uptake of water by osmosis from adjacent xylem. Resultant pressure forces the sugar solution to flow to sink. At sink sugars are converted to starch for storage or use in respiration
