transport in plants Flashcards
what are xylem and phloem made up of?
specialised cells
where are the xylem and phloem found in a plant?
both are continuous from the root, through the stem and into the leaf
what do xylem and phloem form?
vascular bundles in plants
what does xylem carry around the plant and where to?
water and minerals from the roots to the leaves
what does phloem carry and where to?
they carry food substances such as sugars up and down stems to growing and storage tissues
what is transport of food substances called?
translocation
what is transport of minerals called?
transpiration
what is another name for xylem cells?
vessels
why does an xylem cell have a hollow lumen?
because of its lack of living cytoplasm
what give s the xylem cells strength and ssupport
their cellulose walls have extra thickening of lignin
what is a phloem cell?
a living cell that is arranged in collumns
what is transpiration?
the evaporation and diffusion of water from inside leaves
what is evaporation?
changing from a liquid to a gas
what does the loss of water by evaporation help create?
a continuous flow of water from the roots to the leaves in xylem cells
what are root hairs?
projections form root hair cells
how are root hairs adapted?
the produce a large surface area for water uptake by osmosis
what does transpiration ensure?
that plants have water for cooling by evaporation, photosynthesis and support from cells turgor pressure and for transport of minerals
how is the rate of transpiration increased and decreased?
in light intensity, temperature and air movement and a decrease in humidity
what is humidity?
the amount of water vapour in the atmosphere
how is the structure of a leaf adapted?
to prevent too much water loss which could cause wilting
how is water loss reduced?
by having a waxy cuticle covering the outer epidermal cells and by most stomatal openings
where are stomatal openings found?
the shaded lower surface of a leaf
how are plant leaves adapted for photosynthesis?
by having stomata for entry and exit of gases
how does water escape through stomata?
the spongy mesophyll cells are covered with a film of water in which the gases can dissolve
how can the rate of transpiration be increased?
an increase in light intensity, which results in stomata being opened
an increase in temperature, causing an increase in the evaporation of water
an increase in air movement, blowing away air containing a lot of evaporated water
what do guard cells contain?
chloroplasts
what does this mean?
so photosynthesis will produce sugars , increasing turgor pressure, causing the cell walls to swell
why does the guard cell curve, opening the stomata?
due to differential thickness of their walls
how is further reduction of water loss caused?
by having fewer stomata, smaller stomata, the position of stomata and their distribution
