t2-plant organisation Flashcards
what is the epidermal tissue
-reduces water loss by evaporation
-covered in waxy cuticle
what is the palisade mesophyll
-absorbs sunlight efficiently
-lots of chloroplasts on top of the leaf
what is the spongy mesophyll
-allows gases to diffuses in/out
what is the meristem
-allows plant to grow
-can differentiate
what happens in transpiration
-xylem transports water and minerals up the roots and stem into the leaves
4 purposes of transpiration
-provides water for photosynthesis
-transports mineral ions
-cools the leaf as water evaporates
-provides water that keeps the cells turgid
characteristics of xylem
-no end walls- continuous, hollow tube
-strengthened by lignin as the cells are dead
how does humidity affect the rate of transpiration
-decreases rate
-if humidity is too high, there’s a reduced concentration gradient
how does temperature affect the rate of transpiration
-increases rate
-molecules have more energy so they move faster
-evaporation happens at a faster rate
-rate of photosynthesis also increases
-so more stomata are open for gaseous exchange
-so rate of transpiration increases
how does light intensity affect the rate of transpiration
-increases rate
-leads to increased rate of photosynthesis
-so more stomata are open for gaseous exchange
-so more water can evaporate
how does air movement affect the rate of transpiration
-increases rate
-if more air is moving away from leaf the concentration of water vapour around the leaf will be lower
-so more water can evaporate
what happens in translocation
-phloem moves food substances that the plant has produced from photosynthesis up or down
characteristics of phloem
-sieve tubes which are specialised for transport
-companion cells that supply energy
2 purposes of translocation
-developing seeds
-growing parts of the plant for immediate use
