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Nutrients in plants - Coggle Diagram
Nutrients in plants
external leaf structure
lamina
large flat surface
maximize sunlight for maximum rate of photosynthesis
thin layer
carbon dioxide can rapidly reach the inner cells of the leaf
leaf arrangement
leaves always grow opposite each other to prevent blocking each other from sunlight
network of veins
carry water and minerals to the cells in the lamina
carry manufactured food such as glucose from these cells to other parts of the plant
petiole
hold the lamina away from each other to prevent the leaves from blocking each other from sunlight
photosynthesis has 2 stages
light dependent stage
light energy is absorbed by chlorophyll and then converted into chemical energy
light energy is also used to split water molecules into oxygen and hydrogen atoms. this is called photolysis
12H2O goes through photolysis to give you 6O2 and 24H
light independent stage
hydrogen produced in photolysis is used to reduce carbon dioxide to carbohydrates such as glucose
the formation of glucose from carbon dioxide does not require light.
both stages needs enzymes
6CO2 + 24H = C6H12O6 + 6H2O
6CO2 + 6H2O = C6H12O6 + 6O2
what happens to glucose
used immediately for cellular respiration and create cellulose cell walls
during day time, rate of photosynthesis is so great that the glucose produced cannot be used up fast enough and is stored in the form of starch
in darkness, photosynthesis stops and and starch is converted back into glucose
glucose converted to sucrose
transported to other parts of plant or storage organs, like seeds, stem tubers or root tubers via the phloem
reacts with nitrates and other mineral salts to form amino acids in leaves. amino acids in the leaves will form protein which is used for synthesis of new protoplasm
glucose gets converted into which are then used for storage, cellular respiration, and synthesis of new protoplasm
Leaf structure (internal)
Upper epidermis
no chloroplast
waxy and transparent cuticles
reduce water loss through evaporation and allows sunlight to enter
mesophyll
palisade
has 1 or 2 layers of closely packed cylindrical cells
contain numerous chloroplasts
spongey
irregular in shapes
numerous large intercellular air spaces between them
lesser chloroplasts than palisade
thin film of moisture
vascular bundle made up of the xylem and the phloem
lower epidermis
many openings called stomata
functions of stomata
during the day
the guard cells photosynthesize, converting light energy into chemical energy
chemical energy is then used to pump potassium ions into the guard cells from neighboring epidermal cells
water potential of the guard cells is lowered, the water from neighboring epidermal cells enters the guard cells through osmosis
increasing the turgidity of the guard cells causing them to be swollen
the guard cell's cell wall is thicker on one side therefore 1 side of the stomata becomes more swollen and curved, pulling the stoma open
during the night
the accumulated potassium ions will be diffused out, increasing the water potential
water leaves the cell via osmosis, causing the guard cell to be flaccid, leading to the stomata closing
no chloroplasts
how carbon dioxide enter the leaf through stomata
when photosynthesis occurs, carbon dioxide is used up rapidly. this causes the leaf to have a lower concentration of carbon dioxide compared to the concentration of carbon dioxide in the atmosphere, creating a concentration gradient. Therefore, carbon dioxide diffuses from the surrounding air through the stomata into the air spaces in the leaf
surface of mesophyll cells are covered with a thin film of moisture so that carbon dioxide can dissolve in it
dissolved carbon dioxide can then enter the cell
how water and mineral salts enters the leaf
xylem transports water and mineral salts from the roots to the leaf
once out of the veins, the water and mineral salts move from cell to cell right through the mesophyll of the leaf
