IGCSE BIO 6. plant nutrition

reason why leaves are thin

to shorten diffusion distance for CO2

reason why leaves are broad

to receive as much sunlight as possible

cuticle and its functions

transparent waxy outermost layer of leaves, prevents loss of water due to transpiration

epidermis and its functions

transparent layer with no chlorophyll allowing penetration of sunlight, closely packed cells and stomata on lower epidermis, prevents entry of microbes and allows diffusion of CO2 and O2 through stomata

mesophyll layers and its functions

has lots of chloroplast to absorb light to perform photosynthesis

adaptation of palisade mesophyll tissue

closely vertically packed cells with many chloroplasts, to allow absorption of most possible sunlight for most possible photosynthesis

adaptation of spongy mesophyll tissue

has air spaces between them, which allows diffusion of CO2 into mesophyll cells for photosynthesis

function of xylem

transports water and minerals to leaf for photosynthesis

function of phloem

transport product of photosynthesis from source to sink

photosynthesis

process by which plants synthesize carbohydrates form raw materials including CO2 and water, using energy from light

chemical formula for photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2

type of carbohydrate that is directly made by photosynthesis

glucose

form of carbohydrate for transportation within plants

sucrose

why glucose cannot be transported directly?

too reactive, soluble, has osmotic potential

why starch is suitable for storage purpose?

non-reactive, insoluble

plant obtain nitrogen in form of…

nitrate ions

how nitrogen is used in plants?

in forming amino acids and proteins, for growth

how magnesium is used in plants

in forming chlorophyll

deficiency symptoms of nitrogen in plants

stunted growth, smaller stems and roots, pale green upper leaves & yellow lower leaves, v-shaped yellowing

deficiency symptoms of magnesium in plants

yellowing between veins of leaves, yellow upper leaves & pale green lower leaves

limiting factor

something present in the environment in such short supply that it restricts life processes

limiting factors in photosynthesis

light intensity, CO2, stomata, temperature

indicator for CO2 and its colour change (higher → lower concentration

hydrogen carbonate : yellow - orange - red - purple / limewater : milky