T2 plant tissues, organs and systems Flashcards
how is epidermal tissue adapted for their function
epidermal tissue covers the entire plant
has a waxy cuticle which helps reduce water loss from the leaf surface
how is palisade mesophyll tissue adapted for its function
contain lots of chloroplasts which allows photosynthesis to progress at a rapid rate
how is spongy mesophyll tissue adapted for its function
has lots of air spaces which allow gases to diffuse in and out
how is 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 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 meristem tissue adapted for its function
made up of stem cells which can differentiate into many different cell types, allowing the plant to grow
what tissues does the leaf organ contain
epidermis palisade mesophyll spongy mesophyll xylem phloem guard cells
function of guard cells
control the opening and closing of the stomata, according to the water content of the plant
how are stomata adapted for their function
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
how are root hair cells adapted for their function
allow the uptake of water and mineral ions from the soil
large SA - maximises rate of absorption
contain lots of mitochondria - release energy for active transport of mineral ions
what is translocation
movement of dissolved sugars from the leaves to other parts of the plant
what is transpiration
evaporation of water vapour from the surface of a plant
how does transpiration work
water evaporates from the leaf surface via 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 temperature affect the rate of transpiration
increasing temp, increases rate
higher rate of evaporation and diffusion of water - therefore rate of transpiration is increased
how does humidity affect the rate of transpiration
increasing decreases
high relative humidity will reduce the water vapour concentration gradient.
Rate of evaporation will decrease, and so will the rate of transpiration
