Energy from Sunlight

The Carbon Cycle

Human CO2 emissions smaller-than-natural-emissions.htm smaller-than-natural-emissions.htm Photosynthesis Overview sci.life.stru.photosynth/ sci.life.stru.photosynth/ A different kind of fuel a.ws.process.diffuel/ a.ws.process.diffuel/

Hydrothermal Vents – Life without light National geographic Life in other planets/moons Y Y at-nasa/2001/ast13apr_1/ at-nasa/2001/ast13apr_1/ anet/deep_sea/vents_seeps/ anet/deep_sea/vents_seeps/ David Attenborough

As in cellular respiration, the chemical equation for photosynthesis summarizes several reaction steps

Overall equation for photosynthesis CHLOROPLAST

Leaf_anatomy.svg.png

The two main stages of photosynthesis are: the light reactions, which occur in the thylakoids, and the Calvin cycle (light independent reactions), which occurs in the stroma

Different forms of electromagnetic energy have different wavelengths. Shorter wavelengths have more energy than longer wavelengths

A substance’s color is due to chemical compounds called pigments Most plants do not absorb green color, they reflect it Absorbed light

Types of pigments in plants Chlorophyll a: Absorbs mainly blue-violet and red light and reflects mainly green light Chlorophyll b: Absorbs mainly blue and orange light and reflects yellow-green Carotenoids: Absorb mainly blue-green light and reflect yellow-orange.

Harvesting Light Energy - Photosystems

Photosystem model Chlorophyll 1 Chlorophyll 2 Chlorophyll 3 (Reaction-center Chlorophyll) Primary Electron Acceptor Water Molecule Light source

The light energy boosts the electrons up to their excited states

The Calvin Cycle

By converting light energy to chemical energy, photosynthesis is the first step in the flow of energy through an ecosystem.

Photosynthesis TableStagesLocationINPUTOUTPUT Light Reactions Calvin Cycle

Photosynthesis TableStagesLocationINPUTOUTPUT Light Reactions THYLACOIDSLIGTH H 2 O ATPNADPHO2 Calvin Cycle STROMA CO 2 ATPNADPHSUGARNADP+ ADP + P

Compare contrast

Snail & elodea Investigation Bromylthymol blue is blue in the absence of CO 2 and is yellow to clear when CO 2 is present. Do snails give off CO 2 ? Do snails give off CO 2 in the dark? Does elodea give off CO 2 ? Does elodea give off CO 2 in the dark?

ELODEA, SNAILS, & CO 2 LIGHT DARK

Analysis questions 1. How do snails affect the level of CO 2 in the test tubes? 2. How does Elodea affect the level of CO 2 in the test tubes? 3. What is the purpose of test tube #4? 4. Which of the test tubes is an example of a balance system? Why? 5. How do you explain the difference in color (if any) between the test tubes kept under the light, and the ones in the dark? (Compare #1in the light with #1in the dark, and so on)

Tube contents Prediction: What color do you think the tube will be after 24 hours? Observations: Actual color of tube after 24 hours. Prediction: What color do you think the tube will be after 24 hours? Observations: Actual color of tube after 24 hours. 1. ELODEA+ SNAILS 2. SNAILS 3. ELODEA 4. NOTHING IN THE LIGHTIN THE DARK