plant tissues and organs Flashcards
function of xylem
non living transport tissue in plants which transports water and dissolved minerals from soil to roots to leaves
function of phloem
living transport tissue in plants which carries sugars and amino acids from the leaves to the rest of the plant
function of epidermis
outder layer of cells in a plant which protect against dehydration
function of palisade mesophyll
layers of rectangular shaped cells packed full of chloroplast which carry out photosynthesis
function of meristem
rapidly dividing, undifferentiated cells found in growing regions of stems and roots. it differentiates to form other types of cells needed
function of spongy mesophyll
plant tissue with rounded cells, creating air spaces and a large surface area to facilitate the diffusion and exchange of gases
what does the xylem transport
water and dissolved minerals
what does the phloem transport
sugar and amino acids
function of roots
take up water and mineral ions
anchor the plant
function of stem
transports sugars, water and minerals through vascular bundles
supports leaves and flowers
function of leaf
absorb sunlight and carry out photosynthesis
function of flowers
reproductive organs which allow a plant to produce new plants
where is the meristem found
the growing tip of a plant shoot
what is translocation
the process of moving dissolved sugars from the source to where they are needed in the sink, it takes place in the phloem and requires energy -> active process
why is translocation important for plants?
sugars are only produced in the leaves, so they need to be transported to other parts of the plants for respiration
properties/structure of phloem tissue
made up of living cells arranged end to end which develop into tubes. they have cellulose cell walls and contain very little cytoplasm. no nuclei or organelles
kept alive by companion cells
what is the wall at the end of each cell in the phloem tissue called?
sieve plate which contains small pores
what do the small pores in the sieve plate allow you to do?
it allows dissolved sugars to pass from one cell to the next in a long tube
what do garden pests such as greenfly larvae feed on? and what’s the effect
they feed on sugars in the phloem sieve tubes by piercing it with their mouthparts. there is now less glucose for respiration which means less energy is released and less growth
what travels in the phloem
sucrose (NOT GLUCOSE)
what is the transpiration stream
movement of water and dissolved mineral ions from the root to the stem and leaves which takes place within the xylem vessels
what do the walls of xylem vessles contain
lignin (a woody substance) which are impermeable
why is the transport of water and mineral ions so important for plants
it’s needed for photosynthesis and to keep plant cells turgid which keeps the plant upright and prevents it from wilting. mineral ions contain nitrates for growth and magnesium to make chlorophyll
compare structures of xylem and phloem
xylem is made up of dead cells, where as the phloem is made up of living cells. the xylem transports water and dissolved minerals in the transpiration stream, where as in the phloem, sugars are transported. transpiration in the xyelm is a passive process where as translocation in the phloem is an active process which requires energy