Obtaining EnergyAutotrophs –

auto – troph – - make their own food

Heterotrophs – hetero – - eat other organisms to obtain energy

Chemoautotrophs – make food using chemicals instead of sunlight (found in hot springs and in the deepest parts of the ocean)

(Almost) All energy ultimately comes from the sun, nearly all life on earth relies on plants to turn the sun’s energy into a usable form.

•Where does nearly all Where does nearly all energy ultimately come energy ultimately come from?from?

•What is a heterotroph?What is a heterotroph?–Give an example.Give an example.

Ingredients for Photosynthesis

Water – enters plants through the roots

Sunlight – captured by the thylakoid membranes in the chloroplast

Carbon dioxide – (CO2)enters the leaf through the stoma (pores)

Products of PhotosynthesisOxygen (O2) – released as a waste

product

Glucose (C6H12O6) – carbohydrate used for food

•Tell the 3 ingredients of Tell the 3 ingredients of photosynthesis.photosynthesis.

•Tell the 2 products of Tell the 2 products of photosynthesis.photosynthesis.

Formula for Photosynthesis

6CO2 + 6H2O light C6H12O6 + 6O2

Notice, ingredients go on the left, products go on the right.

The arrow is like an equal sign. If energy needs to be added to a reaction

for it to occur, it goes above the arrow.

•Why is light written Why is light written above the arrow in the above the arrow in the formula?formula?

Chloroplasts• Chloroplast are green due to a green

pigment called chlorophyll which absorbs the light.

• Each chloroplast is filled with stacks of thylakoids.

Steps of PhotosynthesisPhase 1 – Light Reaction1. Light hits the thylakoid membrane in the

chloroplast.2. Light energy breaks water into H+, e-, and

O.2H2O light 4e- + 4H+ + O2

3. Electrons and protons (H+) travel along the electron transport chain to turn NADP+ into NADPH and ADP into ATP.(This is like recharging dead rechargeable batteries.)

Phase 2 – Calvin Cycle4. CO2 enters the leaf through the

stoma. 5. ATP and NADPH give up their energy

to CO2 and H+ from NADPH to produce C6H12O6.

6. Oxygen is released.

•What are the 2 phases What are the 2 phases of photosynthesis?of photosynthesis?

•Describe each phase Describe each phase to your partner.to your partner.

ATP and NADPH aren’t stable enough to store energy long term, which is why energy is stored as glucose.

Glucose stores energy much more efficiently than ATP or NADPH.

•Why is energy stored as Why is energy stored as glucose rather than ATP glucose rather than ATP or NADPH?or NADPH?

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