Internal structure of a dicot leaf with relation to its functions

Structure and function of dicot leaf
– Generally thin and flattened
– exposes large surface to sunlight
– shape is maintained by turgidity of living cells
– mid-ribs and strengthening tissue add to strength
– network/reticulate venation
– cuticle is more on the upper surface than lower
– transverse section shows two distinct layers of palisade and spongy mesophyll
– palisade is immediately below the upper epidermis
– spongy immediately below the palisade
– cellulose cell wall are thin and permanently saturated with moisture
– large air spaces/chambers between spongy mesophyll cells
– lots of stomata on lower epidermis and fewer on upper epidermis
– guard cells regulate opening and closing of stomata
– controls the rate of loss of water and also gaseous exchange
– both palisade and spongy mesophyll contain chloroplast
– used for photosynthesis
– vascular tissues (xylem and phloem) situated within spongy
– xylem transports water and mineral nutrients
– phloem transports manufactured food and other organic materials

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