1. Photosynthesis, Respiration & Chemical Energy

2. Quick review: Chemical Changes
Chemical reactions occur when old bonds break and new bonds form.

3. Chemical reactions involve two main changes that you can observe:
formation of new substances
changes in energy (ex: chemical to mechanical)

4. Snap Pow O O Snap Pow Pow H H C Snap Pow Pow H H Pow O O
Old Bonds Break
New Bonds Form
© Beadle, 2009

5. Photosynthesis: Respiration:
Living things get their energy from chemical reactions called: Photosynthesis and Respiration
Photosynthesis:
The energy of the sun powers the reactions of Water (H2O) and Carbon Dioxide (CO2) in plants to make Glucose (C6H12O6) and Oxygen (O2 )(plant poop)!
Respiration:
Animals breath in O2 and eat plants for Glucose (the most basic food). Then they exhale Carbon Dioxide and water.
So what is the Photosynthesis rxn formula?
So what is the Respiration rxn formula?

6. Photosynthesis (endothermic reaction)
Photosynthesis takes place in the Plant Cells
The Chloroplasts are where
Light, water and Carbon Dioxide
are processed into glucose and oxygen
Chloroplast

7. Photosynthesis (Molecules go in…) Sun Energy Light Carbon Dioxide
Chloroplasts
Water molecules
© Beadle, 2009

8. Photosynthesis
(New ones come out…)
Oxygen is a waste product
that leaves the plant (plant poop!)
Energy
Stored Inside
(Potential Chemical)
Glucose is used by
the plant for it’s food
Chloroplasts
Without Photosynthesis, nothing else could exist on this planet! YEAH! Go hug a tree and say “thanks!”

9. (Exothermic Reaction)
Respiration
(Exothermic Reaction)
Respiration takes place in
the animal cells
Mitochondria
(Human Cell)
The “Mitochondria” is where chemical
energy is converted into mechanical
and heat energy
© Beadle, 2009

10. Respiration (Molecules go in…) Glucose Molecule Oxygen Molecules
Mitochondria
(Human Cell)
Oxygen and Glucose molecules
react with each other in the
mitochondria and form new molecules
our bodies use the released energy
to do stuff
Our bodies are designed to unpack that energy stored in the sugar through a series of exothermic reactions.
© Beadle, 2009

11. Respiration (Different ones come out…) Unpack Stored Energy
(Released Energy)
Mitochondria
(Human Cell)
Note: The process by which sugar is broken down is a lot more complicated than a just a simple reduction of sugar – You’ll learn how in your Biology class in High School.
© Beadle, 2009

12. Energy Transformation Sequence:
Sun
Unpack
Stored Energy
Released in Mechanical
& Heat Energy
Chemical Energy
Light Energy
Mechanical
& Heat Energy
Light comes from the sun
Plants convert that energy into chemical energy via sugar
We eat the sugar and convert that energy into heat & mechanical energy

13. Now we send back our “waste products” to the plants!
Every time we exhale, we send CO2 and H2O back to plants
Plants change the CO2 and H2O into Glucose
and O2 that comes back to us

14. Why is this cycle so important?
Remember the tragedy of the Stromatolites…
4 Billion years ago, the atmosphere was mostly CO2,
Which is GREAT for photosynthesis!!!
Moral: NOTHING CAN SURVIVE
IN IT’S OWN WASTE!!!!
All the CO2 in the atmosphere eventually became O2.
Which means what for our Stromatolite friends…?
Stromatolites are the earliest form of life we have
ever found… the first ones, maybe as long as 4 BILLION years ago!!!
Some still survive today as you can see in this picture:
They are living bacteria that form rock like features when they
grow together. It looks a bit like a coral reef
Moral: NOTHING CAN SURVIVE
IN IT’S OWN WASTE!!!!
They (like modern plants) did Photosynthesis
But there were NO animals around yet…why is this a problem?
A: There were no critters to turn the O2 back into CO2,
and the Stromatolites died off!!! Poor things…

15. How long would you last…?
Stuck in a sealed room with nothing but CO2?