Part 1
Respiration & Photosynthesis
Key Question: Why do we need to eat food?
Initial Thoughts:
• Cells need energy to do work.
• For example: moving your muscles, thinking
with your brain, fighting off illnesses, etc.
(remember back to the Human Body Unit)
• Our cells need Oxygen and sugar (glucose) to
produce energy to perform their functions.
• As a byproduct (waste), CO2 (carbon dioxide)
and H2O (water) are given off.
• We breathe in O2, breath out CO2
• Plants can make their own food using sunlight
as energy.
• What organelle do plants use to do this?
Chloroplast
It’s what makes
plants GREEN
Plants absorb water through their roots
& CO2 through their leaves.
Plants use sunlight to help transform
CO2 and water into energy (glucose).
Plants store their energy in the
form of sugars.
• When you eat potatoes, rice, beans, or wheat
flour, you are eating big molecules of glucose
called starch, made through photosynthesis.
Starches are a type of carbohydrate.
Photosynthesis and Cellular Respiration Activity
• Work with a partner, but each of you must record
your equations & answers in your journal. Write
down your initial thoughts.
• 1. Set-up an equation for Cellular Respiration (use the
following): C6H12O6 (Glucose), CO2, Energy, H20, O2
• 2. Set-up an equation for Photosynthesis (use the
following): C6H12O6 (Glucose), CO2, Energy, H20, O2
glucose/sugar
O2 + C6H12O6
Reactants
(what goes in)
ATP
H20 + CO2+ E
Products
(What comes out)
glucose/sugar
H20 + CO2+ E
O2 + C6H12O6
Reactants
(what goes in)
Products
(What comes out)
• As a byproduct (waste), plants give off Oxygen.
• Humans consume/eat plants and need the
oxygen they make. Humans are called
CONSUMERS. (Remember Ecology!)
• Plants and all photosynthetic organisms are called
PRODUCERS because they produce their own
food. (More Ecology!!)
The Cycle
CO 2
Consumers
O2
Producers
1. Explain what gases are involved in
Photosynthesis and Respiration. Which ones are
inputs, and which are by-products?
2. Compare the chemical equations for
photosynthesis and cellular respiration. How are
they similar? How are they different?
3. Do you think plants do cellular respiration?
Explain your reasoning.
In a well developed paragraph:
– What did you think before about how plants &
animal cells use food? (look back at your initial
thoughts)
– What did you learn about how plants & animal cells
use food?
Be specific! (look back at your evidence section).
– What evidence do you have that you learned this?
– Further Thoughts
Make sure this is thoughtful and thorough.
• Create a diagram that shows how glucose and
water are recycled between producers and
consumers.
• - (make your own big idea)