plant organisation Flashcards
How is epidermal tissue adapted for its
function?
Epidermal tissue covers the entire plant. It
has a waxy cuticle which helps reduce water
loss from the leaf surface.
How is the xylem adapted for its function?
● Made up of dead cells which form a continuous
hollow tube - allows the movement of water and
mineral ions from the roots to the leaves.
● Strengthened by lignin - makes the vessel strong and
waterproof.
● Has bordered pits - allow minerals to be transported
to specific places.
How is palisade mesophyll tissue adapted for
its function?
Palisade mesophyll tissue contains lots of
chloroplasts which allows photosynthesis to
progress at a rapid rate.
How is the phloem adapted for its function?
● Made up of elongated living cells.
● Cells have sieve plates that connect them
together - cell sap can move through plates
into other cells.
● Sieve tube cells have few organelles to allow
the efficient transport of substances.
How is spongy mesophyll tissue adapted for its
function?
Spongy mesophyll tissue has lots of air
spaces which allow gases (including
oxygen and carbon dioxide) to diffuse in
and out
How is meristem tissue adapted for its function?
Made up of stem cells which can
differentiate into many different cell types,
allowing the plant to grow
How are root hair cells adapted for their function?
Root hair cells allow the uptake of water and
mineral ions from the soil.
● Large surface area - maximises rate of
absorption.
● Contain lots of mitochondria – release energy
for active transport of mineral ions.
What tissues does the leaf organ contain?
● Epidermis
● Palisade mesophyll
● Spongy mesophyll
● Xylem
● Phloem
● Guard cells
How are stomata adapted for their function?
Stomata allow the control of gaseous exchange and
water loss from the leaf.
● More stomata on the base of the leaf - minimises
water loss as this side is cooler and shaded.
● Have guard cells which control their opening and
closing.
What is the function of guard cells?
Guard cells control the opening and closing
of the stomata, according to the water
content of the plant.
What is translocation?
Translocation is the movement of
dissolved sugars from the leaves to other
parts of the plant
What is transpiration?
Transpiration is the evaporation of water
vapour from the surface of a plan
How does transpiration work?
Water evaporates from the leaf surface via the
stomata.
● Water molecules cohere together - more water is
pulled up the xylem in an unbroken column.
● More water is taken up from the soil - creating a
continuous transpiration stream.
How does humidity affect the rate of transpiration?
Increasing relative humidity decreases the rate of
transpiration.
● High relative humidity will reduce the water
vapour concentration gradient. The rate of
evaporation will decrease, and so will the rate of
transpiration.
How does temperature affect the rate of transpiration?
Increasing the temperature increases the rate
of transpiration.
● Higher rate of evaporation and diffusion of
water - therefore rate of transpiration is
increased.
