b2.3 photosynthesis
TRANSCRIPT
![Page 1: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/1.jpg)
B2.3 Photosynthesis
![Page 2: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/2.jpg)
B2.3 Photosynthesis
Green plants and algae use light energy to
make their own food. They obtain the raw
materials they need to make this food from
the air and the soil. The conditions plants are
grown in can be changed to promote growth.
![Page 3: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/3.jpg)
You need to be able to:
■ interpret data showing how factors affect
the rate of photosynthesis
■ evaluate the benefits of artificially
manipulating the environment in which plants
are grown.
![Page 4: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/4.jpg)
Key words
Photosynthesis
Glucose
Chlorophyll
Chloroplasts
Algae
Carbon dioxide
![Page 5: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/5.jpg)
Leaves
![Page 6: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/6.jpg)
Function of leaves
• Trap light energy for photosynthesis
Producing sugar from photosynthesis
• Exchange of gases –
oxygen and carbon dioxide
![Page 7: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/7.jpg)
![Page 8: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/8.jpg)
Structure
Wide
Helps to catch more light
energy
Thin
Help get carbon dioxide
from bottom to top of
leaf for photosynthesis
![Page 9: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/9.jpg)
Leaf structure
Greener on top
CO2 gets in
here
![Page 10: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/10.jpg)
Leaf diagram – palisade layer
CO2
Most
chlorophyll
![Page 11: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/11.jpg)
Leaf cell - palisade
Position?
Upper surface of
leaf
Features?
Box shape
Chloroplasts
Function?
Photosynthesis
![Page 12: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/12.jpg)
Gas exchange
• Leaves are designed to allow carbon
dioxide to get to the main chlorophyll layer
at the top of the leaf
• They have small holes called stomata on
the under surface
• Each hole is open & closed by 2 guard
cells
![Page 13: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/13.jpg)
Leaf diagram –
stoma and guard cells
![Page 14: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/14.jpg)
Stoma position
![Page 15: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/15.jpg)
Stoma is a small hole
Its size is controlled by 2 guard cells
closed open
![Page 16: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/16.jpg)
Stoma function is for gas
exchange in the leaf
Carbon dioxide
oxygenGuard cell
Provided plant is photosynthesising
![Page 17: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/17.jpg)
Stomata open and
close at different
times of the day
When it is light the
plant needs CO2 for
photosynthesis so
the stoma open
At night (darkness)
they close
![Page 18: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/18.jpg)
Gas exchange
![Page 19: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/19.jpg)
Cross section of a leaf
Add the labels to your diagram
![Page 20: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/20.jpg)
The top surface has
a thick waxy
cuticle to stop water
evaporating from the
cells
The top layer of cells is
closely packed and
contain lots of
chloroplasts because
these carry out most of
the photosynthesis
(Palisade layer)
Cross section of a leaf
Veins contain xylem
tubes to carry water to
the leaf cells from the
roots and via the stem
Pores called stoma let
gases in/out the leaf. They
are on the bottom so they
are not blocked and are
shaded to prevent
evaporation. Guard cells
can shut them to control
water loss
The lower layer of
cells has air spaces
between to let carbon
dioxide move
towards the top
surface and a big
surface area for gas
exchange
Add the labels to your diagram
![Page 21: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/21.jpg)
Roots – function and structure
• Hold plant in position
• Absorb water and minerals from the soil
• Specialised cells to increase surface area for water intake
![Page 22: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/22.jpg)
Wheat seed
Root hairs
Fragile parts of
cells that grow
from the main root
They massively
increase the
surface area for
absorption
![Page 23: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/23.jpg)
Root hair cells (x150)
![Page 24: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/24.jpg)
Root ‘B’ has had
the hairs damaged -
Toughened root cap
![Page 25: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/25.jpg)
![Page 26: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/26.jpg)
![Page 27: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/27.jpg)
![Page 28: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/28.jpg)
![Page 29: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/29.jpg)
![Page 30: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/30.jpg)
e) The glucose produced in photosynthesis may be
converted into insoluble starch for storage. Plant cells
use some of the glucose produced during
photosynthesis for respiration.
![Page 31: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/31.jpg)
f) Some glucose in plants and algae is used:
■ to produce fat or oil for storage
■ to produce cellulose, which
strengthens the cell wall
■ to produce proteins.
![Page 32: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/32.jpg)
g) To produce proteins, plants also use
nitrate ions that are absorbed from the
soil.
![Page 33: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/33.jpg)
In a science fiction book, a villain threatens to
spray the countryside with a chemical that
destroys chlorophyll (the green substance in
plants).
What effect will this have on plant life?
Explain your answer as fully as you can.
![Page 34: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/34.jpg)
A farmer cuts his meadow for hay.
He noticed that the grass he cut was
green, but the stalks were yellow.
How do you explain this?
![Page 35: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/35.jpg)
A small tree is planted in a meadow. After
20 years it has grown into a big tree,
weighing 250 kg more than when it was
planted.
Where do you think the extra 250 kg come
from?
Explain your answer as fully as you can.
![Page 36: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/36.jpg)
Plants and minerals
A number of plants seedlings are placed into a water culture and fed with
various nutrients.
One is fed with only distilled water, the others are fed with nutrients but one
without Nitrogen, another without Iron, another without Magnesium and
another without Phosphorous. The final one is fed with all the nutrients.
![Page 37: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/37.jpg)
Describe the appearance of the plants in
each tray
Which plant looks healthiest?
What can you conclude?
![Page 38: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/38.jpg)
![Page 39: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/39.jpg)
Very
little
growth
Poor
growth
Yellowish
leaves
■ to produce fat or
oil for storage
■ to produce
cellulose, which
strengthens the
cell wall
■ to produce
proteins.
Carbon dioxide + water -> Glucose + Oxygen 6CO2 + 6H2O -> C6H12O6 + 6O2
![Page 40: B2.3 photosynthesis](https://reader035.vdocuments.us/reader035/viewer/2022062300/55a221da1a28ab2b368b4822/html5/thumbnails/40.jpg)
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-
game.aspx?game_id=125606