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Biology unit 1
1.5
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Cards (17)
Cuticle
transparent
- allows light through to lower layers containing
chlorophyll
waxy
and
waterproof
- reduces water loss
Palisade layers
cells are packed with
chloroplasts
for
photosynthesis
Phloem
transports
sugar
away from leaf
Xylem
brings
water
to leaf
Guard cells
open and close the
stomata
allow
carbon dioxide
to enter
prevents
water loss
Spongy
layer
contains large
air
spaces
- allows
carbon
dioxide
to reach
palisade
cell for photosynthesis
cells here contain
chloroplasts
- for
photosynthesis
Photosynthesis
carbon dioxide
+
water
--(
light
energy and
chlorophyll
)->
glucose
+
oxygen
Limiting factors
light intensity
carbon dioxide concentration
temperature
water
Light intensity
1/distance²
rate of photosynthesis + light intensity increases
standstill occurs due to limiting factors such as temperature and carbon dioxide concentration
Carbon dioxide concentration
rate of
photosynthesis
+
co2
concentration increases
standstill occurs due to
limiting
factors such as temperature and
light intensity
Temperature
rate of
photosynthesis
+
kinetic
energy increases
reaches
optimum
temperature (around
20
°c )
enzyme denatures (around
25
°c)
Water
increasing it doesn't increase the rate of
photosynthesis
too much will kill the plant by driving
oxygen
out of the soil - killing the
roots
of the plant
Phloem structure
two
way flow of
water
and food -
photosynthesis
products
end walls with
perforations
sucrose
goes down to be glucose in the sink
glucose splits into
starch
which is insoluble and won't effect
osmosis
and controls the pressure produced
Xylem structure
One way flow of
water
and
minerals
carries water
uptake
from
root hairs
in soil
water enters
leaf
and
spongy mesophyll
layer
water
evaporates
out of stomata - drawing more water up towards the leaf through the
xylem vessel
cohesions
(each other) and
adhesion
(walls)
walls of vessel are strengthened with
lignin
Root hairs
water is in higher concentration (
lower
water concentration) in soil than in the
root
hair
mineral ions are
pumped
against concentration current, from
low
to high
process requires
ATP
energy - a product of
aerobic
respiration
KPN fertilisers
ensures plants are taking in essential minerals
nitrate
deficiency - poor plant growth
phosphate
deficiency - poor root growth
potassium
deficiency - yellowing of leaf
Structure of a leaf
A -
cuticle
B - upper
epidermis
C -
palisade
layer
D - phloem
E - xylem
F - lower epidermis
G - guard
cells
H - stoma
I -
spongy
layer