B4 plants

Question 1

epidermal tissues

Answer 1

cover the surfaces and protect them
secrete waxy substance that waterproofs surface of leaf

Question 2

palisade mesophyll

Answer 2

contains lots of chloroplasts, to carry out photosynthesis
located under the upper epidermis for optimal sunlight

Question 3

spongy mesophyll

Answer 3

contains some chloroplasts for photosynthesis
big air spaces
large SA to make diffusion of gases easier

Question 4

xylem

Answer 4

carry water and dissolved mineral ions from roots to leaves
strengthened by lignin
dead tissue

Question 5

phloem

Answer 5

carry dissolved sugars from leaves around plant (made by photosynthesis)
-make new plant cells
- energy store for winter
live tissue

Question 6

translocation

Answer 6

movement of sugars from the leaves to the rest of the plant through the phloem

Question 7

transpiration

Answer 7

loss of water vapour from the surface of plant leaves

Question 8

how water is lost

Answer 8

stomata open/close
controlled by guard cells
water evaporates from lining of air spaces
passes out of leaf through diffusion

Question 9

factors increasing stomatal opening

Answer 9

any factors increasing photosynthesis
humidity, temperature, air flow and light intensity
more rapid in hot, dry, windy , bright conditions

Question 10

factors affecting rate of transpiration

Answer 10

light intensity- increases
humidity- decreases
air flow- increases
temperature- increases

Question 11

stomata

Answer 11

in lower epidermis
when open they make diffusion of gases in and out of leaf easier
opened and shut by guard cells

Question 12

how guard cells open/close stomata

Answer 12

GC take in lots of water and swell, opening stomata
GC lose water and return to a limp state, closing stomata