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 –

Chloroplasts – Chlorophyll -

the sugar made in photosynthesis

the organelle in plant cells where photosynthesis happens.

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) C6H12O6 + 6O2

Carbondioxide

water light glucose oxygen

reactants products

9. Why are carbon dioxide and water needed for photosynthesis?

6CO2 + 6H2O + energy C6H12O6 + 6O2 Carbondioxide

water light Glucose(sugar)

oxygen

• They provide the carbon, hydrogen, and oxygen atoms needed to make glucose.

• CO2 and H20 molecules are taken apart, and their atoms are re-assembled into glucose and oxygen.

10. Why are light and chlorophyll needed for photosynthesis?

6CO2 + 6H2O + energy C6H12O6 + 6O2 Carbondioxide

water light Glucose(sugar)

oxygen

• Light provides the energy needed to take apart CO2 and H20 molecules.

• Chlorophyll enables plant cells to absorb light energy for photosynthesis.

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-fascinating-story-of-photosynthesis-and-food-amanda-ooten