Plant Cell Organisation Flashcards
photosynthesis requires lots of carbon dioxide to make…
sugars
how is water transported to the leaves?
comes from the soil and is transported to the leaves via the root and xylem
how does carbon dioxide enter the leaf?
carbon dioxide diffuses directly into the leaf via the stomata
where are stomata found?
stomata are found in the lower epidermis
adaption of the spongy mesophyll layer
lots of air gaps between the cells so that carbon dioxide can easily diffuse through to the next layer
adaption of the palisade mesophyll layer
where most photosynthesis happens and so the palisade cells are packed full of chloroplasts
upper epidermis
transparent to allow sunlight to pass though to get to the chloroplasts in the palisade cells beneath
parts of the cell starting from the bottom up
lower epidermis, spongy mesophyll, palisade mesophyll, upper epidermis
how are the sugar molecules produced my photosynthesis carried to the rest of the plant
by the phloem
the xylem continuously bring water up from the roots for the palisade cells to use for photosynthesis. To reduce water loss the leaf has a waxy cuticle on top (a thin waterproof layer of lipids) that water cant get through. The leaves keep their stomata open for as short a time as possible to maximize carbon dioxide absorption and minimise water loss
explain how guard cells become turgid
When the plant cells have lots of water the guard cells will be turgid, making the gaps between them larger allowing more carbon dioxide to diffuse through
explain how guard cells become flaccid
when the plant is short of water, the guard cells will lose water due to osmosis and become flaccid which in turn closes the stomata meaning the plant no longer takes in carbon dioxide but more importantly it will conserve its water vapour
why do the guard cells close at night?
guard cells are sensitive to light so they close at night time, when photosynthesis is not taking place and they don’t need carbon dioxide
why are the stomata at the bottom of the leaf
it is more shaded which makes it cooler so therefore less water will evaporate
meristem tissue
the plant form of stem cells, they are found at the growing tip of the roots and shoots, and can differentiate into loads of different cell types so that the plant can grow
