Carbon Cycle-Carbon moves from inorganic (carbon dioxide) to organic (sugar) and back.
e.g: 1. producer (grass) >>> photosynthesis >>> organic
2. consumer eats producer >>> organic
3. consumer eats consumer >>> organic
4. both producer & consumer >>> inorganic
*No other chemical process on the planet matches the output of photosynthesis.
Greenhouse effect-CO2 in the atmosphere traps heat from the sun (would otherwise escape from Earth back to space.) >>> Keeps the world climate warm enough for living things.
*The greenhouse effect keeps the average temperature on Earth some 10'c warmer than it would be otherwise.
Concept Check 8.4
1. Give an example of carbon moving from an inorganic compound to an organic compound in the carbon cycle. Give an example of carbon moving from an organic to an inorganic compound.
Plants (producers) produce glucose (organic) through the process of photosynthesis. It uses carbon dioxide (inorganic).
Humans (consumers) release carbon dioxide (inorganic) through te process of respiration, which needs glucose (organic) as the reactant.
2. How is carbon dioxide important to Earth's climate?
Carbon dioxide in the atmosphere traps heat from the sun so that it would not escape from Earth back into space (greenhouse effect).
Vocabulary
Carbon cycle-the process by which carbon moves from inorganic to organic compounds and back.
Greenhouse effect-a property of carbon dioxide which keeps the world climate warm enough for living things.
Monday, November 17, 2008
Wednesday, November 12, 2008
Concept 8.3 Summary
A cycle=a process in which the starting material is regenerate each time the process occurs.
*The Calvin Cycle=RuBP, the starting material of the process, gets regenerated.
The Calvin Cycle
-input (reactant)=carbon (CO2), energy (ATP), high-energy electrons and hydrogen ions (NADPH)
-output (product)=G3P (energy-rich sugar molecule)
*The plant cell uses G3P as the raw material to make glucose and other organic molecules.
-steps:
(1) 3 carbon molecules (3CO2) enters the cycle, then combines with 3 RuBP molecules, producing 3 six-carbon molecules,
(2) 3 six-carbon molecules break down into 6 three-carbon molecules (3-PGA),
(3) ATP and NADPH from light reactions provide energy and electrons. It results 6 3-PGA
changing into 6 G3P (direct product of photosynthesis),
(4) Carbon (G3P) exits the cycle,
(5) 5 G3P (containing 15 carbon atoms) left in the cycle,
(6) ATP provides energy. It results G3P changing into RuBP,
ADP and NADP+ return to light reactions.
Photosynthesis Summary
-The Light Reactions:
-takes place in the thylakoid membranes
-converts light energy to the chemical energy of ATP and NADPH
-reactant: water
product: oxygen
-The Calvin Cycle:
-takes place in the stroma
-reactant: carbon dioxide
product: sugar (G3P) * uses ATP and NADPH from the light reactions.
Concept Check 8.3
1. Where are the inputs and outputs of the Calvin cycle?
The inputs are carbon dioxide, ATP and NADPH.
The outputs are sugar molecules (G3P).
2. Which stage of photosnthesis uses each reactant from the overall photosynthesis equation? Which stage generates each product from the overall photosynthesis equation?
The light reactions use water, and generate oxygen.
The Calvin Cycle uses carbon dioxide, and generates sugar (glucose).
3. Why is the Calvin cylce called a cycle?
Because it has a starting material, RuBP (a sugar with five carbons), that gets regenerated each time the Calvin cycle process occurs.
4. What molecule is the direct product of photosynthesis? How is that molecule then used by plant cells?
The direct product of photosynthesis is G3P. It is used by plant cells to make glucose and other organic compounds.
Monday, November 10, 2008
Concept 8.2 Summary
Wave lengths (the distance between two adjacent waves) that are shorter than those of visible light (400nm~700nm, seen as different colours by the eyes) can damage organic molecules such as proteins and nucleic acids.
*Being exposed to UV, which has shorter wavelengths than those of visible light, can cause sunburns and lead to skin cancer.
A substance's color is due to chemical compounds called pigments. When light shines on a material that contains pigments, three things can happen to the different wavelengths: absorbed, transmitted, or reflected.
*Leaves look green-because they don't absorb green light.
-they only absorb blue-violet and red-orange light.
Photosystem
-a cluste containing chlorophyll and other pigment molecules, including chlorophyll a, chlorphyll b, and carotenoids.
-steps: 1. One of the pigment's electrons gains energy when a pigment molecule absobs light energy --> the electron is raised from a low-energy "ground state" to a high-energy "excited state"
2. The excited electron falls back to the ground state.
3. It then transfers the energy to a neighbouring molecule.
4. It excites an electron in the receiving molecule.
5. The electron falls back to the grand state.
6. The energy is transferred in this way, until it reaches the reaction center of the photosystem.
*The reaction center consists of a chlorophyll a molecule and a primary electron acceptor.
7. The primary electron acceptor traps the excited electron from chlorophyll a.
8. Other teams of molecules built into the thylakoid membrane can now use that trapped energy to make ATP and NADPH.
The Steps of the Light Reactions:
1. The first photosystem="water-splitting photosystem"
-traps light energy, and tranfers the light-excited electrons to an electron transport chain.
-releases oxygen (waste product), releases H+.
2. The electron transport cain="connection" between two photosystems
-releases energy, which the chloroplast uses to make ATP.
*It's really similar to the one in cellular respiration.
-similarity: an electron chain pumps H+ across a membrane-inner mitochondrial
-thylakoid membrane
-main difference: -in respiration, food provides electrons for the electron transport chain.
-in photosynthesis, light-excited electrons from chlorophyll travel down the chain.
3. The second photosystem="NADPH-producing photosystem"
-produces NADPH by transferring excited electrons and H+ to NADP+.
Concept Check 8.2:
1. Explain why a leaf appears green.
Because the pigments in the leaf's chloroplasts transmit or reflect the green light, not absorbing it.
2. Describe what happens when a molecule of chlorophyll a absorbs light.
The excited electron then transfers the energy to the chlorophyll a molecule, which then transfers its excited electron to the primary electron acceptor. Then, the light reaction goes on.
3. Besides oxygen, what two molecules are produced by the light reactions?
ATP and NADPH.
4. Where in the chloroplast do the light reactions take place?
In the membrane of thylakoids.
Vocabulary
wavelength-the distance between two adjacent waves
electromagnetic spectrum-the range of types of electromagnetic energy from the very short wavelengths of gamma rays to the very long wavelengths of radio waves
pigment-a chemical compound which a substance's colour is due to
paper chromatography-a laboratory technique in which you could observe the different pigments in a green leaf
photosystem-a cluster which within the thylakoid membrane, chlorophyll and other molecules are arranged in
*Being exposed to UV, which has shorter wavelengths than those of visible light, can cause sunburns and lead to skin cancer.
A substance's color is due to chemical compounds called pigments. When light shines on a material that contains pigments, three things can happen to the different wavelengths: absorbed, transmitted, or reflected.
*Leaves look green-because they don't absorb green light.
-they only absorb blue-violet and red-orange light.
Photosystem
-a cluste containing chlorophyll and other pigment molecules, including chlorophyll a, chlorphyll b, and carotenoids.
-steps: 1. One of the pigment's electrons gains energy when a pigment molecule absobs light energy --> the electron is raised from a low-energy "ground state" to a high-energy "excited state"
2. The excited electron falls back to the ground state.
3. It then transfers the energy to a neighbouring molecule.
4. It excites an electron in the receiving molecule.
5. The electron falls back to the grand state.
6. The energy is transferred in this way, until it reaches the reaction center of the photosystem.
*The reaction center consists of a chlorophyll a molecule and a primary electron acceptor.
7. The primary electron acceptor traps the excited electron from chlorophyll a.
8. Other teams of molecules built into the thylakoid membrane can now use that trapped energy to make ATP and NADPH.
The Steps of the Light Reactions:
1. The first photosystem="water-splitting photosystem"
-traps light energy, and tranfers the light-excited electrons to an electron transport chain.
-releases oxygen (waste product), releases H+.
2. The electron transport cain="connection" between two photosystems
-releases energy, which the chloroplast uses to make ATP.
*It's really similar to the one in cellular respiration.
-similarity: an electron chain pumps H+ across a membrane-inner mitochondrial
-thylakoid membrane
-main difference: -in respiration, food provides electrons for the electron transport chain.
-in photosynthesis, light-excited electrons from chlorophyll travel down the chain.
3. The second photosystem="NADPH-producing photosystem"
-produces NADPH by transferring excited electrons and H+ to NADP+.
Concept Check 8.2:
1. Explain why a leaf appears green.
Because the pigments in the leaf's chloroplasts transmit or reflect the green light, not absorbing it.
2. Describe what happens when a molecule of chlorophyll a absorbs light.
The excited electron then transfers the energy to the chlorophyll a molecule, which then transfers its excited electron to the primary electron acceptor. Then, the light reaction goes on.
3. Besides oxygen, what two molecules are produced by the light reactions?
ATP and NADPH.
4. Where in the chloroplast do the light reactions take place?
In the membrane of thylakoids.
Vocabulary
wavelength-the distance between two adjacent waves
electromagnetic spectrum-the range of types of electromagnetic energy from the very short wavelengths of gamma rays to the very long wavelengths of radio waves
pigment-a chemical compound which a substance's colour is due to
paper chromatography-a laboratory technique in which you could observe the different pigments in a green leaf
photosystem-a cluster which within the thylakoid membrane, chlorophyll and other molecules are arranged in
Concept 8.1 Summary
Chloroplast-the cellular organelle where photosynthesis takes place
*The leaves contain the most chloroplasts and are the major sites of photosynthesis:
*Some of the steps of photosynthesis take place in the thylakoid membranes, while others take place in the stroma.
1. The Light Reactions (takes plae in thylakoids' membranes)-
-converts the sunlight energy to chemical energy
-steps: 1. chlorophyll molecules (in the membrane) capture light energy
2. the chloroplasts use the captured energy to remove electrons from water
--> it splits H2O into O2 and H+
3. O2 goes out into the atmosphere through the stomata
4. the chloroplasts use electron and H+ to make NADPH
5. the chloroplasts use the captured enrgy to generate ATP
*NADPH is an electron carrier, similar to NADH, an energy-rich molecule.
-results=light energy-->chemical energy-NADPH
-ATP
2. The Calvin Cycle (takes place in the stroma)-
-makes sugar from the atoms in CO2 and H+ and high-energy electrons in NADPH
-the enzymes for the cycle are outside the thylakoids and dissolved in the stroma
*The leaves contain the most chloroplasts and are the major sites of photosynthesis:
1. the chloroplasts are concentrated in the cells of the mesophyll
2. carbon dioxide enters and oxygen exits the leaf through the stomata (located on the surface)
3. Veins carry water and nutrients from the roots to the leaves. They also deliver organc molecules produced in the leaves to other parts of the plant.
*Some of the steps of photosynthesis take place in the thylakoid membranes, while others take place in the stroma.
1. The Light Reactions (takes plae in thylakoids' membranes)-
-converts the sunlight energy to chemical energy
-steps: 1. chlorophyll molecules (in the membrane) capture light energy
2. the chloroplasts use the captured energy to remove electrons from water
--> it splits H2O into O2 and H+
3. O2 goes out into the atmosphere through the stomata
4. the chloroplasts use electron and H+ to make NADPH
5. the chloroplasts use the captured enrgy to generate ATP
*NADPH is an electron carrier, similar to NADH, an energy-rich molecule.
-results=light energy-->chemical energy-NADPH
-ATP
2. The Calvin Cycle (takes place in the stroma)-
-makes sugar from the atoms in CO2 and H+ and high-energy electrons in NADPH
-the enzymes for the cycle are outside the thylakoids and dissolved in the stroma
Concept Check 8.1
1. Draw and label a simple diagram of a chloroplast that includes the following structures: outer and inner membranes, stroma, thylakoids.
2. What are the reactants for photosynthesis? What are the products?
Reactants: CO2, H2O
Products: C6H12O6, O2
3. Name the two main stages of photosynthesis. How are the two stages related?
The light reaction, and the Calvin cycle.
The Calvin cyce process needs the supply of ATP and NADPH from the light reaction process, in order to make sugar.
Vocabulary 8.1
Chloroplast-the cellular organelle where photosynthesis takes place
Chlorophyll-chemical compounds inside chloroplasts that give these organelles a green colour
Stroma-a thick fluid enclosed by the inner membrane of a chloroplast
Thylakoid-a disk-shaped sac suspended in the stroma
Light reaction-a process that converts te energy in sunlight to chemical energy
Calvin cycle-a process that makes sugar from the atoms in carbon dioxide plus the hydrogen ions and high-energy electrons carried by NADPH
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