B4 plants Flashcards
epidermal tissues
cover the surfaces and protect them
secrete waxy substance that waterproofs surface of leaf
palisade mesophyll
contains lots of chloroplasts, to carry out photosynthesis
located under the upper epidermis for optimal sunlight
spongy mesophyll
contains some chloroplasts for photosynthesis
big air spaces
large SA to make diffusion of gases easier
xylem
carry water and dissolved mineral ions from roots to leaves
strengthened by lignin
dead tissue
phloem
carry dissolved sugars from leaves around plant (made by photosynthesis)
-make new plant cells
- energy store for winter
live tissue
translocation
movement of sugars from the leaves to the rest of the plant through the phloem
transpiration
loss of water vapour from the surface of plant leaves
how water is lost
stomata open/close
controlled by guard cells
water evaporates from lining of air spaces
passes out of leaf through diffusion
factors increasing stomatal opening
any factors increasing photosynthesis
humidity, temperature, air flow and light intensity
more rapid in hot, dry, windy , bright conditions
factors affecting rate of transpiration
light intensity- increases
humidity- decreases
air flow- increases
temperature- increases
stomata
in lower epidermis
when open they make diffusion of gases in and out of leaf easier
opened and shut by guard cells
how guard cells open/close stomata
GC take in lots of water and swell, opening stomata
GC lose water and return to a limp state, closing stomata