Energy from Sunlight

Biology – Exploring Life - Chapter 8

The Carbon Cycle

• Human CO2 emissions• http://

www.skepticalscience.com/human-co2-smaller-than-natural-emissions.htm

• Photosynthesis Overview• http://www.teachersdomain.org/resource/tdc02.s

ci.life.stru.photosynth/• A different kind of fuel• http

://www.teachersdomain.org/resource/vtl07.la.ws.process.diffuel/

Hydrothermal Vents – Life without light

National geographic• http://www.youtube.com/watch?v=XotF9fzo4VoLife in other planets/moons• http://www.youtube.com/watch?v=4QqmUBbfn6Y• http

://science.nasa.gov/science-news/science-at-nasa/2001/ast13apr_1/

• http://wwf.panda.org/about_our_earth/blue_planet/deep_sea/vents_seeps/

David Attenborough• http://www.youtube.com/watch?v=BXGF3XS-yAI

As in cellular respiration, the chemical equation for photosynthesis summarizes

several reaction steps

Overall equation forphotosynthesis

CHLOROPLAST

http://upload.wikimedia.org/wikipedia/commons/thumb/9/90/Leaf_anatomy.svg/769px-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

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 Table

Stages Location INPUT OUTPUT

Light Reactions

Calvin Cycle

Photosynthesis Table

Stages Location INPUT OUTPUT

Light Reactions

THYLACOIDS

LIGTHH2O

ATPNADPH

O2H+

Calvin Cycle STROMA

CO2H+

ATP NADPH

SUGARNADP+ADP + P

Snail & elodea Investigation• Bromylthymol blue is blue in the absence of

CO2 and is yellow to clear when CO2 is present.

• Do snails give off CO2?

• Do snails give off CO2 in the dark?

• Does elodea give off CO2?

• Does elodea give off CO2 in the dark?

ELODEA, SNAILS, & CO2

LIGHT DARK

Analysis questions

1. How do snails affect the level of CO2 in the test tubes?

2. How does Elodea affect the level of CO2 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

Hypothesis: What color

do you think the

tube will be after 24 hours?

Observations: Actual color of

tube after 24 hours.

Hypothesis: 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 LIGHT IN THE DARK