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biology 0610printed 70 · PDF 70
328 pagesrevision 46933
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Palisade mesophyll
Tall narrow cells containing very large number of chloroplasts as their main function is
to photosynthesis. As they are on the top they receive a large amount of sunlight.
Spongy mesophyll
These cells also contain chloroplasts but not as much as palisade cells. The cells are
not packed tightly enough. They contain air spaces which allow carbon dioxide and
oxygen to diffuse in and out.
Lower epidermis
Similar to upper epidermis except that it doesn't make cuticle because from
underneath the cell the loss of water vapour is very less. In the lower epidermis there
is an opening called stomata. Stomata allow the diffusion of carbon dioxide and
oxygen in and out of the leaf. Each stomata is surrounded by guard cells. Unlike other
cells in epidermis, guard cells contain chloroplast.
Magnesium is needed for making chlorophyll and nitrate ions are needed for making
amino acids
Without these ions, a plant has deficiencies and yellowing and paling of leaves occurs
consequently
Factors affecting photosynthesis
There are various factors affecting photosynthesis
Supply of raw materials(carbon dioxide and water)
Quantity of sunlight
Temperature