2. Autotrophs vs. Heterotrophs
Autotroph
Make their own
food
Example: Plants
Heterotroph
Obtain energy from
foods they eat
Example: Animals,
fungi
4. Chemical Energy
Energy – the ability to do work
Adenosine Triphosphate (ATP)
Adenine
Ribose
3 phosphate groups
ADP + P
Adenosine diphosphate + phosphate
10. Light and Pigment
Plants gather the Sun’s energy
with light absorbing molecules
called pigments
Chlorophyll (Green)
chlorophyll a and chlorophyll b
15. Light-Dependent Reactions
Location: Thylakoid Membrane
1. Photosystem II
Light energy absorbed by electrons
and increases their energy level
Enzymes break up water molecules
into:
2 electrons
2 hydrogen ions
1 oxygen atom
16. Light-Dependent Reactions
Location: Thylakoid Membrane
2. Electron Transport Chain
High-energy electrons move
hydrogen ions from the stroma
into the inner thylakoid space
17. Light-Dependent Reactions
Location: Thylakoid Membrane
3. Photosystem I
Uses energy from light to re-energize
the electrons.
NADP+ picks up electron and 2 H+
ions
Produces NADPH
18. Light-Dependent Reactions
Location: Thylakoid Membrane
4. Hydrogen Ion Movement
Hydrogen ions move
across the thylakoid
membrane making the
inside positively charged
19. Light-Dependent Reactions
Location: Moves from Thylakoid to Stroma
5. ATP Formation
Hydrogen ions pass through ATP
synthase (protein)
Energy is converted from ADP
to ATP
23. Calvin Cycle
Location: Stroma
1. Carbon Fixation
6 CO2 combines with a
five-carbon sugar
Enzyme breaks down to
12 three-carbon molecules
24. Calvin Cycle
Location: Stroma
2. Energy Input
ATP is broken down giving each
three-carbon molecule a
phosphate
NADPH gives up electrons to
provide more energy
25. Calvin Cycle
Location: Stroma
3. Sugar Production
2 three-carbon molecules exit
cycle to be used by the plant
10 three-carbon molecules are
recycled
26. Calvin Cycle
Location: Stroma
4.5-Carbon Molecule Regeneration
10 three-carbon molecules are
converted back into 6 5-carbon
molecules to be used in the next
cycle
6 ATP molecules are used to complete
this process
27.
28.
29. Factors Affecting Photosynthesis
Water
Plants in dry conditions have a waxy coating
on the leaves that reduce water loss
Temperature
Photosynthesis depend on enzymes that
function best between 0oC and 35oC
Light Intensity
Increasing light intensity increases the rate
of photosynthesis
However, a plant has a maximum rate of
photosynthesis that can be reached