Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It occurs in two stages: the light-dependent reactions where light energy is captured to make ATP and NADPH, and the light-independent reactions where carbon dioxide is incorporated into organic compounds to make glucose. The rate of photosynthesis depends on factors like light intensity, carbon dioxide concentration, temperature, and amount of chlorophyll present. Photosynthesis is essential as it provides the primary source of energy and organic molecules on Earth.

1. CELL ENERGY 1
Photosynthesis
ppt. by Robin D. Seamon

2. LIFE CHEMISTRY: CHON
Carbon C
Hydrogen H
Oxygen O
Nitrogen N
Cells put these atoms together to make useful
molecules for food and energy.
VIDEO: Elements in Living Things (7 min)

3. 4 Macromolecules for LIFE:
1. Carbohydrates: (sugars)
2. Lipids: (fats & oils)
3. Proteins: (amino acids)
4. Nucleic acids: (DNA & RNA)
Glucose is a
carbohydrate
VIDEO: Macromolecules- a beginner guide

4. C A R B O H Y D R A T E S
• Sugars, starches,
cellulose
• Have ‘ose’ on the end of
the word
• Made by plants through
photosynthesis.
OTHER WORDS FOR SUGAR:
Glucose (grape sugar, corn
sugar, dextrose)
Fructose (honey)
Galactose (part of milk…
lactose)
Monomer:
(small organic blocks)
CH2
Polymer:
(large organic blocks)
C H O
6 12 6

5. IMPORTANCE OF WATER TO LIVING THINGS

6. HOW DO PLANTS GET WATER?
• Small, simple plants like mosses and liverworts
absorb water through simple diffusion; they
must live in wet spaces

7. • More advanced plants use
roots to absorb water and a
vascular system to pull the
water up to other parts of
the plant
• Therefore, these plants can
get taller
Xylem: path that water &
minerals take up the plant
Phloem: path that glucose
from leaves take down the
plant

8. •Transpiration-
process by which
plants lose water
through the leaves
99% water taken
into roots are
transpired out the
leaves
2. Water through
cortex of root to
xylem & up stem
1. Water from soil
into root hairs
3. Transpiration in
leaves helps draw
water up stem
4. Water moves
up stem to veins
to cells
As water
transpires out
of the stomata,
capillary action
pulls up the
next molecule…
water moves
up the tree
VIDEO: The Most Amazing Thing
about Trees (7 min)

9. ENERGY
MOVEMENT
VOCABULARY
simple diffusion photosynthesis caretonoids
transpiration reactant enzyme
phloem product
xylem carbohydrate
light energy starch
chemical energy stroma
thermal energy thylakoid
glucose grana
chlorophyll light reaction
stomata dark reaction

10. SUN
light
energy CHLOROPLAST
chemical
energy
Glucose&
Oxygen
MITOCHONDRIA
chemical
energy
Water &
CO2
CELL PROCESSES thermal
energy (heat)
ATP
chemical
energy

11. PHOTOSYNTHESIS
• process by which autotrophs convert the sun’s
energy into glucose
• Occurs in the chloroplasts of plant and some
protist cells
• Glucose C6H12O6
BREAK IT DOWN
Photo- light
Synthesis- making

12. GLUCOSE
6-carbon chain sugar
MACROMOLECULE: Carbohydrate = sugar = glucose
• Provides energy for the organism

13. 6
carbon
dioxide
molecules
6
water
molecules
6
oxygen
molecules
1
glucose
YIELDS+ +
CHEMICAL REACTIONS- only move in one direction:
reactants YIELD products
REACTANTS PRODUCTS
HOW TO READ:

14. HOW DOES THIS OCCUR IN PLANTS?

15. Light reactions- “light trapping’ steps of
photosynthesis:
• Happens in the chloroplasts of mesophyll cells
“CATCHING SUNLIGHT”

17. Stroma:
colorless
fluid
surrounding
the grana;
dark
reactions
occur here
(Calvin
Cycle)

18. Thylakoid:
each of the
flattened
sacks in the
chloroplast;
stacked up
into grana
towers;
light
dependent
reactions
happen
here

19. Granum:
stacks of
thylakoids;
embedded
in the
stroma;
light-
dependent
reactions
happen
here

20. Chloroplasts contain chlorophyll-
green pigment that traps sunlight

21. 1. Chlorophyll- main
pigment type
Absorbs blue and red
wavelengths
2. Carotenoids-
secondary pigment
types
Absorbs violet to green
wavelengths
Pigment: a substance that absorbs light and
produces color

22. Leaf stoma- opening in the leaf that allows the
exchange of gases.
CO2 enters
O2 and H2O exits

24. • When the plant has adequate water, the
stoma remain open
• When the plant needs water, the stoma close
to prevent water loss… temporary condition

25. Since both H2O and CO2 are required for
photosynthesis, it’s important that the plant stays
hydrated.

26. During this first (light) part of
photosynthesis, light hits the
chlorophyll and “knocks” apart
the water molecule into Oxygen
and Hydrogen
Given off as oxygen
gas by plants
Goes to ATP
molecule

27. “Dark reactions”
During the second part of photosynthesis, the
trapped energy is used to make glucose from
carbon dioxide.
• Also called light independent reaction
• Also called Calvin Cycle
*NOTE: These reactions can
occur in the light or dark*
VIDEO: Nature’s Smallest factory: The Calvin Cycle (5:30)

28. REVIEW:

29. REACTANTS PRODUCTS
LIGHT
REACTIONS
DARK
REACTIONS
1st2nd

30. • Some plants make and store a lot of sugar: starch
• We eat these plants
• We also isolate the sugar to sweeten things

31. At the end of the photosynthesis process,
glucose and oxygen are released.
VIDEO: Amoeba Sisters- Photosynthesis and the Teeny Tiny Pigment Cakes

32. 1. Chlorophyll absorbs light
from the sun
2. Sun’s energy splits water
molecule into hydrogen &
oxygen
3. Hydrogen joins
carbon dioxide to
make food
(sugar/glucose)
4. Sugar carried through the
plant; oxygen is released into
the air
6 6 6
H2O O2CO2 =+ + C6 H12 O6
PHOTOSYNTHESIS
MOVE
(Very over-simplified)
CC VIDEO: #8
Photosynthesis
(10 min)

33. How do you measure the rate of
photosynthesis?
• Rate of oxygen output
• Rate of carbon dioxide uptake
• Rate of carbohydrate production
Elodea photosynthesizing

34. Rate of Photosynthesis
• Depends on
• enzymes and how they work
• Light intensity
• CO2 concentration
• Temperature
• Amount of chlorophyll

35. Rate of Photosynthesis
Light intensity
• Increasing light intensity increases rate of
photosynthesis until another limiting factor
becomes in short supply. Then it will
plateau

36. Rate of Photosynthesis
CO2 concentration
• If concentration of CO2 increases, so will
photosynthesis, again until a limiting factor
causes this rate to
plateau

37. Rate of Photosynthesis
Temperature
• The chemical reactions are controlled by
enzymes (proteins that cause a reaction to
happen)
• Temperature can affect
the usefulness of an
enzyme: at high
temperatures, enzymes
are denatured
(become unusable)

38. Rate of Photosynthesis
Amount of chlorophyll
• Plants with poor lighting conditions are
darker b/c the plant produces more
chlorophyll to absorb required light
• Some plant diseases affect amount of
chlorophyll which affects photosynthesis
• Variegated varieties
require more light b/c
of lack of chlorophyll
pigment

39. VIDEO: Photosynthesis: Crash Course #8

40. EXTRA