transport in plants Flashcards
what is the function of the xylem?
to transport water and mineral salts
what are the features of the structure of xylem?
- thick walls with lignin
- walls joined end to end to form a long continuous
tube - no cell contents
what is the function of the phloem
to transport sucrose and amino acids
xylem + phloem
vascular bundle!!!!
how do root hair cells increase water uptake?
large surface area, elongated, no chloroplasts
describe the pathway of water in the root
root hair cells, root cortex cells, xylem, mesophyll cells
how are mineral salts transported from root hair cell to xylem?
through active transport
how is water transported from root hair cell to xylem?
through osmosis
what is transpiration?
the loss of water from plant leaves by evaporation of water at the surfaces of mesophyll cells followed by the diffusion of water vapour through the stomata
what are the factors affecting transpiration
- temperature (+, +)
- wind speed (+, +)
- light intensity (+, +)
- humidity (+, -)
why does transpiration increase in high temperetures
warm air can hold more water vapour than cold air. when the sun shines of leaves, they absorb heat which warms them up and increases the rate of evaporation
why does transpiration increase at high wind speeds?
water vapour is swept away from the leaf as fast as it diffuses out in moving air, which speeds up transpiration
why does high light intensity increase rate of transpiration?
the stomata open during the day, making room for water vapor to diffuse out of the leaf
why does high humidity decrease rate of transpiration?
if the air contains a lot of water vapour (is humid) there will be more water vapour outside of the leaf
what instrument is used to measure transpiration?
a mass or volume potometer
what is transpiration pull?
the mechanism by which water moves
upwards in the xylem that draws up a column of water molecules, held together by forces of attraction between water molecules (cohesive and adhesive)
what is translocation?
the movement of sucrose and amino acids in phloem from sources to sinks
what are sources?
parts of plants that release sucrose and amino acids
what are sinks?
parts of plants that use sucrose or amino acids
