1.1 Plant roots are adapted to take water
and mineral ions from the soil as
efficiently as possible. The roots
themselves are thin, divided tubes
with a large surface area. The cells on
the outside of the roots near the
growing tips have special adaptations
that increase the surface area. These
rootsa hair cells have tiny projections
fromt he cells which push out between
the soil particles.
1.2 Water moves into the
roots cells across the
membrane. It then has a
short distance to move
across the root to the
1.3 Plant roots are adapted to take in mineral ions using
active transport. It has plenty of mitrochondria to supply
the energy it needs. They have the advantages of a large
surface area and short pathways for movement of water
2 GAS EXCHANGE IN PLANTS
2.1 Plants need carbon dioxide and
water from photosynthesis to take
place. They get the carbon dioxide
they need from their leaves.
2.1.1 The flattened shape of
the leaves increases the
surface area for
18.104.22.168 Most plants have thin leaves which means
the distance the carbon dioxide has to
diffuse from the air to the cell is kept short
22.214.171.124 Leaves have many air spaces in their structure which allows CO2 to come
into contact with lots of cells and give a large surface area for diffusion
2.2 Problem: Leaf cells loose water by evaporation
. If CO2 could diffuse quickly in and out of the
leaves water vapour would be lost quickly .
2.2.1 When it is dark , they don't need CO2
because they are not photosynthesising -
but on bright sunny days a lot of CO2
needs to come into the leaves by diffusion
2.3 Leaves are adapted to allow the CO2 in only
when needed. They are covered in a waxy
cuticle and it is waterproof and gasproof layer.
2.3.2 All over the leaf surface are small openings - stomata.
These can be opened when plant need air for leaves.
126.96.36.199 CO2 from the
into the air spaces and
then into the cells along
188.8.131.52.1 At the same time oxygen produced by
photosynthesis is removed from leaf by
by diffusion into surrounding air.
184.108.40.206.1.1 The opening and closing of the
stomata is controlled by guard cells.
Water is lost from the leaves by
diffusion when the stomata are opened.
3 Plants rely heavily on
diffusion to get the
carbon dioxide they
need for photosynthesis
3.1 They use osmosis to take
water from the soil and
active transport to obtain
mineral ions from the soil
3.1.1 Plants have adaptations
that make these exchanges
as efficient as possible.