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plant cell organisation & transpiration and translocation &…
plant cell organisation & transpiration and translocation &transpiration & the rate of transpiration
plant cells are organised into tissues and organs
3) spongy mesophyll tissue this is also in the leaf and contains big air spaces to allow gases to diffuse in and out of cells
4) xylems and phloem's they transport things like water mineral ions and food around the plants
2) palisade mesophyll tissue this is the part of the leaf where most photosynthesis happens
5)meristem tissue this is found at the growing tis of shoots and roots and is able to differentiate ino lots of different types of plant cells allowing the plant to grow
1) epidermal tissue this covers the whole plant
the leaf is an organ made up of several types of tissues
3)the palisade layer has lots of chloroplasts this means that they are near the top of the leaf where they can get the most light
4) the xylem and phloem form a network of vascular bundles which deliver water and other notorious to the entire leaf and take away the glucose produces by photosynthesis they also support the structure.
2)the upper epidermis is transparent so that light pass through it to the palisade layer
5) the tissue of leaves are also adapted for efficient gas exchange lower epidermis is full of little holes called stomata which lets co2 diffuse directly into the leaf the opening and closing of stomata is controlled by guard cells in response to environmental conditions
1)the epidermal tissues are covered with a waxy cuticle which helps to reduce water loss by evaporating
phloem tubes transport food
2) they transport food substances made in the leaves to the rest of the plant for immediate use
3)the transport goes in both directions
1) made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
4) this process is called translocation
xylem tubes take water up
2) they carry water and mineral ions from the roots to the stem and leaves
3) the movement of water from the root through the xylem and out of the leaves is called the transpiration stream
1) made of dead cells joined end to end with no end walls between them and a hole down the middle they are strengthened with a martial called lignin
transpiration is the loss of water from the plant
2) this evaporation creates a slight shortage of water in the leaf and so more water is drawn up from the rest of the plant through the xylem vessels to replace it
3) this is turn means more water is drawn up from the roots and so there's a constant transpiration stream of water through the plant
1) transpiration is caused by the evaporation and diffusion of water from a plant surface most transpiration happens at the leaves
transpiration rate is affected by four main things
temperature
1) the warmer it is the faster transpiration happens
2) when its warm the water particles have more energy to evaporate and diffuse out of the stomata
air flow
1) the better the air flow around a leaf the greater the transpiration rate
2) if air flow around the leaf is poor the water vapour just surrounded the leaf and doesn't move away this means there's a high concentration of water particular outside the leaf as well as inside it so diffusion doesn't happen quickly
3) water vapour is swept away maintaining a low concentration of water in the air outside the leaf diffusion then happens quickly from an area of higher concentration to an area of lower concentration
light intensity
1) the brighter the light the greater the transpiration rate
2) stmata begins to close as it gets darker photo synthesis cant happen in the dark so they don't need to be open to let co2 in when the stomata are closed very little water can escape
humidity
1) the drier the air around a leaf the faster transpiration happens
2) this is like what happens with air flow if the air is humid there's a lot of water in it already so there's not much of a difference between the inside and the outside of the leaf
3) diffusion happens fastest if there's a really high concentration in one place and a really low concentration in the other