Photosynthesis Notes
Essential Questions:
1. How do our cells determine who we are?
2. How do living things obtain and use
energy?
1. What is the difference between autotrophic
organisms and heterotrophs? Give an example of each.
• Autotrophs can make their own food,
heterotrophs have to eat other living things to
get energy.
• Autotrophs: plants
• heterotrophs: animals
2. What is adenosine triphosphate (ATP)? Why is it
important to living things?
• Chemical compound that cells use to store and
release energy.
• Important because all organisms need energy for
life processes – moving, growing, breathing, etc.
3. What is the main difference between ATP (adenosine
triphosphate) and ADP (adenosine diphosphate)?
• ATP has 3 phosphate groups, ADP only has 2
• “tri” = 3, “di” = 2
4. Use the space below to draw simplified diagrams of
an ATP molecule and an ADP molecule as shown on p.
203. Explain how living things use these two molecules
to store or release energy.
• Energy released by breaking bond between 2nd and
3rd phosphate group of ATP, making it ADP.
• Energy stored by adding 3rd phosphate to ADP,
making it ATP.
5. With respect to energy, how are ATP and glucose
similar? How are they different?
• Both are molecules that cells use for energy.
• Glucose is a bigger molecule that holds more energy,
but harder for cells to actually use. Like trying to use
a $100 bill in a vending machine.
• ATP is smaller molecule with less energy, but easier
for cells to use. Like $1 bill.
6. What is photosynthesis?
• Process by which plants make food (sugar) using
light energy.
• “photo” = light, “synthesis” = to make
7. How are each of the following related to photosynthesis?
Glucose – the sugar made in photosynthesis
Chloroplasts – the organelle in plant cells where
photosynthesis happens.
Chlorophyll -
the green pigment in chloroplasts that
absorbs light needed for photosynthesis.
8. Write the chemical equation for photosynthesis
using symbols and words. What are the reactants?
What are the products?
6CO2 + 6H2O + (energy)
Carbon
dioxide
water
reactants
light
C6H12O6 + 6O2
glucose
oxygen
products
9. Why are carbon dioxide and water needed for photosynthesis?
• They provide the carbon, hydrogen, and oxygen atoms needed
to make glucose.
• CO2 and H20 molecules are taken apart, and their atoms are reassembled into glucose and oxygen.
6CO2 + 6H2O + energy
Carbon
dioxide
water
light
C6H12O6 + 6O2
Glucose
(sugar)
oxygen
10. Why are light and chlorophyll needed for photosynthesis?
• Light provides the energy needed to take apart CO2 and H20
molecules.
• Chlorophyll enables plant cells to absorb light energy for
photosynthesis.
6CO2 + 6H2O + energy
Carbon
dioxide
water
light
C6H12O6 + 6O2
Glucose
(sugar)
oxygen
11. How well would a plant grow under pure yellow
light? Use the graph on p. 207 to explain your answer.
• Probably not well.
• Chlorophyll a & b absorb blue and red light very well.
• Neither absorbs green or yellow light well (they reflect
instead).
12. Innovative architect Ian L. McHarg once said, “The
world is dominated by a working partnership between
the sun and the leaf.” Apply what you’ve learned to
explain what you think this means in your own words.
• Almost every food chain on Earth begins with
photosynthesis.
• Plants use sunlight to make sugar, animals eat
plants, etc.
Photosynthesis & Food
http://ed.ted.com/lessons/the-simple-but-fascinatingstory-of-photosynthesis-and-food-amanda-ooten