Plants and structure Flashcards
what are the organs in a plant?
stem
root
flower (reproductive organs)
leafs
what are the layers of a leaf starting from the top?
cutucle
upper epidermis
palisade mesophyll contains pallisade cells
spongy mesophyll
vein going through the leaf (xylem and phloem)
lower epidermis
guard cells and stomata
look at leaf diagram
what is the xylem?
a hollow tube of dead cells strengthened by lignin that carries water from the roots to the leafs
what is the phloem?
a tube made of elongated cells that have end walls with pores between them which allow the transportation of glucose (food) from the leafs to the rest of the plant for immediate use or storage
what is the role of the stoma?
to control gas exchange and water loss
how do plants photosynthesize?
stoma on the underneath of the leaf allow carbon dioxide to diffuse into the leaf
it then moves through the air spaces to the spongy mesophyll and then it diffuses into the palisade mesopyhll cells to be used in photosynthesis
what is transpiration?
transpiration is the loss of water from a plant caused by evaporation
which tube uses translocation and what is it?
the phloem uses translocation which allows food substances to be transported in both directions
how is the phloem specialised?
the phloem cells have very few subcellular structures so that food substances can flow through them easier
how is the xylem specialised?
the xylem cells are hollow in the centre so that water can flow through them easier
how does the xylem get water to the leafs?
water evaporates through the stomata.
this water then must be replaced
the root hair cells absorb the water which then gets pulled upwards through the xylem to the leaves veins then carry it into the leaves to photosynthesize and the process repeats
what is the word equation for photosynthesis?
carbon dioxide + water ——–> glucose + oxygen
how does temperature, wind, light intensity and humidity affect the rate of transpiration?
TEMPERATURE: a hotter temperature means more transpiration as the water has more kinetic energy so more evaporation
WIND: more wind means more transpiration as water vapours are blown away from the leaf so theres a steeper concentration gradient and more water moves out the leaf
LIGHT INTENSITY: a higher light intensity means more transpiration as the stomata will be open to get more CO2 so more evaporation can happen
HUMIDITY:a more humid day will decrease transpiration as the concentration gradient will not be very steep so less water will leave the leaf/ be evaporated
what is the transpiration stream?
the constant flow of water through the the plant (from roots to the leafs)
what can you use to measure the rate of transpiration?
petometre
what factors affect rate of transpiration?
temperature- higher temperature means faster rate
surface area- larger surface area means faster rate
concentration gradient- steeper concentration gradient means faster rate
where is the meristem tissue?
found at the growing tips of shoots and roots
what are the functions of each part of the leaf?
waxy cuticle-waterproof so prevents evaporation
upper epidermis-transparent so allows sunlight to come through
pallisade mesophyll-contains lots of closely packed pallisade cells containing lots of chloroplast
spongy mesophyll-has lots of air spaces to increase surface area for gases to diffuse
lower epidermis-protective
stoma-allow CO2 to enter and oxygen to leave the leaf
guard cells-open or close the stoma
