Lecture 13: Transport in Plants Flashcards
passive transport?
moves molecules short distances or across membranes without the use of energy. passive transport includes diffusion/simple and facilitated diffusion, and osmosis.
diffusion?
movement of molecules down their concentration gradient across a plasma membrane without the use of energy and simple diffusion is directly across the phospholipid bilayer without any help and facilitated diffusion is across the membrane with the use of a transport protein
osmosis?
net movement of water from an area of low solute concentration to an area of high solute concentration
active transport?
movement of molecules against their concentration gradient across a membrane using transport proteins
what is the primary mode of transporting materials in nonvascular plants?
nonvascular plants/bryophytes main mode of transporting material is diffusion. the reason for this is because nonvascular plants have no vascular/transport system. ALL plants use diffusion for gas exchange but the vascular plants use diffusion for everything
cytoplasmic streaming?
cytoplasm circulates around the cells via actin myosin interactions:
- moves nutrients around the cell to speed up the distribution of material
- important in large plant cells
- moves chloroplasts from shady areas to sunny areas for photosynthesis
are gases transported?
no gases arent transported; all living cells do gas exchange directly with the environment
what materials are transported from root to shoot?
water and minerals are transported from root to shoot and released as water vapor from the stomata
what materials are produced by the plant and transported throughout?
sugar that was made via photosynthesis
what tissues perform long distance transport?
vascular tissue: the tissue system is xylem and phloem. the xylem transports water from root to shoot and phloem moves the sugar from the leaf to where it is needed.
SAP: includes the nutrients, water, and sugar being transported long distance. xylem sap consists of mainly water and phloem sap consists of mainly sugar.
are plants or animals more efficient with water?
animals are more efficient with water than plants are: plants lose 95% of the water through evaporation from stomata but most animals resorb water through kidneys and colon, and vascular system.
water moves from — to — via?
water moves from roots to leaves via bulk flow: movement of water from roots to shoots in response to pressure gradient
what are the 3 ways of how water moves up against gravity in plants?
- transpiration-cohesion-tension mechanism
- capillary action
- root pressure
transpiration cohesion mechanism explained in easy way?
in plants, water moves up from the roots to the leaves through tiny tubes called the xylem due to a combination of 3 things including: transpiration, cohesion, and tension.
TRANSPIRATION: when water evaporates from the leaves into the air through the stomata.
COHESION: when water molecules stick together. it pulls more water up behind it.
TENSION: the pull that happens when water evaporates and pulls more water from the roots.
so, transpiration pulls water out of the leaves, cohesion makes water molecules stick together, and tension pulls water up through the plant.
what happens if you stop evaporative water loss in plants?
that would stop water and mineral transport
mesophyll cells are coated with? causing?
mesophyll cells are coated with a film of water causing the humidity to be higher inside of the lead than the surrounding air.
what is capillary action?
the tendency of water to move up a tube due to cohesion, adhesion, and surface tension.
Plants have tiny tubes called xylem, when water gets into the tubes it starts to climb up. Cohesion is water molecules sticking together and adhesion is water molecules sticking to the xylem cell wall. surface tension acts to hold the surface intact.
SO as water moves up the xylem tubes, cohesion and adhesion help it stick together and stick to the sides of the tube.
how far up can capillary action move water up?
only one metre
root pressure?
inside the root of a plant, there are cells that pump minerals and water from the soil into the roots. this pumping action creates pressure pushing the water through the xylem tubes. it helps to push water up the plant especially at night when transpiration isnt happening much.
active transport in root pressure?
the mineral concentration in root hairs is higher than in the soil so it goes against the concentration gradient and atp is required.
where is sugar produced in the plant?
it is produced in mature leaves via photosynthesis
what cells need sugar?
all living cells need sugar
how does sugar get to the right areas?
transported in phloem
how is sugar transported from source to sink? and what is it?
via the pressure flow model. source is organ where photosynthesis occurs or starch is broken down. sugar sink is the organ that consumes or stores starch
source/sink in summer vs spring?
in summer, the leaves are the source and potato is sink and in spring, the potato is the source and the leaves are the sink
pressure flow model?
- sugar moves from the source cell to the sieve tube using active transport: the leaves produce sugar through photosynthesis so they are then loaded onto special cells called source cells using active transport.
- water then moves into the sieve tube by osmosis. the sieve tubes are tubes for the sugars to travel through and the water moves into the seive tubes via osmosis which increases pressure which then pushes sugar through the tubes.
- sugar transported from sieve tube to sink cell using passive transport. the pressure in the seive tube pushes the sugar along the tube towards the sink and into sink cells via passive transport.
- water recycles back into xylem by osmosis. water recycles back into xylem by osmosis.after sugar is unloaded the water in the sieve tube recycles back into the xylem through osmosis.
