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