Biology IGCSE unit 7 Plants

how is the leaf adapted to absorb light?

• large surface area

• thin

• flat

waxy cuticle

prevents transpiration (loss of water vapour) from the leaf

upper epidermis

transparent, allows light to enter the leaf

palisade mesophyll

contains chloroplasts

spongy mesophyll

air spaces allow gases to diffuse

xylem

in the vein, brings water to the leaf

phloem

in the vein, removes sugar

guard cells

control opening and closure of stomata

stomata

allow carbon dioxide into leaf and oxygen out, opens during the day and closes during night

glucose made in photosynthesis is used to make…

• proteins

• fats

• cellulose

how are mineral ions absorbed?

by active transport into root hair cell

what are nitrates used for?

to build proteins

what is magnesium used for?

to make chlorophyll

magnesium deficiency leads to…

yellow leaves

nitrate deficiency leads to…

stunted growth

phloem transports…

glucose, up and down the plant

xylem transports…

water and mineral ions, up the plant

xylem structure

• dead cells, no living cells = more efficient

• continuous column

• lignin, reinforces those walls

phloem structure

• sieve plates

• companion cells, many mitochondria = more efficient