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Concept 8.1: Photosynthesis uses light energy to make food.

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Presentation on theme: "Concept 8.1: Photosynthesis uses light energy to make food."— Presentation transcript:

1 Concept 8.1: Photosynthesis uses light energy to make food

2 I. The structure of Chloroplasts The structure where photosynthesis takes place is the chloroplast. The structure where photosynthesis takes place is the chloroplast. Chloroplasts contain compounds called pigment that give leaves their color. Chloroplasts contain compounds called pigment that give leaves their color. Leaves contain the most chloroplasts. Leaves contain the most chloroplasts. There are tiny pores called stoma that allows carbon dioxide to enter and oxygen to leave the cell. There are tiny pores called stoma that allows carbon dioxide to enter and oxygen to leave the cell.

3 I. The structure of Chloroplasts Veins carry CO2 and H2O from the plants roots to the leaves and deliver organic compounds to other parts of the plant. Veins carry CO2 and H2O from the plants roots to the leaves and deliver organic compounds to other parts of the plant. The inner membrane of a chloroplast encloses a thick fluid called stroma. The inner membrane of a chloroplast encloses a thick fluid called stroma. Suspended in the stroma are many disk shaped sacs called thylakoids which are arranged in stacks called grana. Suspended in the stroma are many disk shaped sacs called thylakoids which are arranged in stacks called grana. These stacks organize the series of reactions that make up photosynthesis. These stacks organize the series of reactions that make up photosynthesis.

4 Photosynthesis

5 II. Overview of Photosynthesis In cellular respiration, electrons fall from glucose to O2 to release energy. In cellular respiration, electrons fall from glucose to O2 to release energy. In photosynthesis, electrons from water are boosted uphill by the energy of sunlight. In photosynthesis, electrons from water are boosted uphill by the energy of sunlight.

6 III. The Light Reactions These excited electrons, along with carbon dioxide and hydrogen ions produce C6H12O6 molecules These excited electrons, along with carbon dioxide and hydrogen ions produce C6H12O6 molecules Photosynthesis occurs in two main steps: Light Reaction and Calvin Cycle (Dark Reaction). Photosynthesis occurs in two main steps: Light Reaction and Calvin Cycle (Dark Reaction).

7 The Light Reactions…cont Light Reactions convert the energy in sunlight to chemical energy. Light Reactions convert the energy in sunlight to chemical energy. Chloroplasts use captured light energy to remove electrons from H2O, splitting it into oxygen and hydrogen ions. Chloroplasts use captured light energy to remove electrons from H2O, splitting it into oxygen and hydrogen ions. The electrons and hydrogen ions are used to make NADPH, which is an electron carrier The electrons and hydrogen ions are used to make NADPH, which is an electron carrier Chloroplasts also use the captured light energy to generate ATP. Chloroplasts also use the captured light energy to generate ATP. The overall result of the light reactions is the conversion of light energy to chemical energy stored in NADPH and ATP. The overall result of the light reactions is the conversion of light energy to chemical energy stored in NADPH and ATP.

8 IV. The Calvin Cycle Calvin Cycle makes sugar from the atoms in carbon dioxide plus the hydrogen ions and high energy electrons carried in NADPH. Calvin Cycle makes sugar from the atoms in carbon dioxide plus the hydrogen ions and high energy electrons carried in NADPH. The ATP made in the light reactions provides the energy to make sugar. The ATP made in the light reactions provides the energy to make sugar. The Calvin Cycle is sometimes referred to as the light-independent reactions because it does not require light energy to begin. The Calvin Cycle is sometimes referred to as the light-independent reactions because it does not require light energy to begin.

9 Concept 8.2 The Light Reactions Convert Light Energy to Chemical Energy

10 I. Light Energy and Pigments Light is a form of energy that travels in waves and the distance between adjacent waves is called a wavelength. Light is a form of energy that travels in waves and the distance between adjacent waves is called a wavelength. The range of wavelengths is called the electromagnetic spectrum. The range of wavelengths is called the electromagnetic spectrum. Visible light only makes up a small portion of the electromagnetic spectrum. Visible light only makes up a small portion of the electromagnetic spectrum.

11 II. Pigments and Color A substances color is due to chemical compounds called pigments. A substances color is due to chemical compounds called pigments. Waves of light shining on a material can be absorbed, transmitted or reflected. Waves of light shining on a material can be absorbed, transmitted or reflected. Leaves absorb blue-violet and red-orange light very well but either reflect or transmit green light and that is why leaves look green Leaves absorb blue-violet and red-orange light very well but either reflect or transmit green light and that is why leaves look green

12 III. Identifying Chloroplast Pigments Using a technique called chromotography different pigments in a leaf can be observed. Using a technique called chromotography different pigments in a leaf can be observed. Chlorophyll a absorbs mainly blue- violet light while chlorophyll b absorbs mainly red light. Chlorophyll a absorbs mainly blue- violet light while chlorophyll b absorbs mainly red light.

13 IV. Harvesting Light Energy Within the thylakoid membrane, chlorophyll and other molecules are arranged in clusters called photosystems. Within the thylakoid membrane, chlorophyll and other molecules are arranged in clusters called photosystems. Each photosystem contains a few hundred pigment molecules, including chlorophyll a and b as well as carotenoids. Each photosystem contains a few hundred pigment molecules, including chlorophyll a and b as well as carotenoids. Each time a pigment molecule absorbs light energy electrons are raised from a ground state to an excited state Each time a pigment molecule absorbs light energy electrons are raised from a ground state to an excited state

14 Concept 8.3: The Calvin Cycle makes sugar from carbon dioxide

15 A Trip around the Calvin Cycle The Calvin Cycle is the sugar factory within the chloroplasts. The Calvin Cycle is the sugar factory within the chloroplasts. The starting material for the Calvin Cycle is regenerated each time the process occurs, the starting material is called RuBP, (a sugar with five carbons) The starting material for the Calvin Cycle is regenerated each time the process occurs, the starting material is called RuBP, (a sugar with five carbons) Inputs for the Calvin Cycle are ATP, CO2 and NADPH. (from light reaction and air thus no light) Inputs for the Calvin Cycle are ATP, CO2 and NADPH. (from light reaction and air thus no light) The cycles output is an energy rich sugar molecule called G3P which is not quite like glucose but it used as the raw material to make glucose as the plant needs to. The cycles output is an energy rich sugar molecule called G3P which is not quite like glucose but it used as the raw material to make glucose as the plant needs to.

16 A Trip around the Calvin Cycle

17 II. Summary of Photosynthesis The overall equation for photosynthesis is: The overall equation for photosynthesis is: 6 CO H 2 O C 6 H 12 O O 2 6 CO H 2 O C 6 H 12 O O 2 Carbon dioxide + water Glucose + Oxygen Carbon dioxide + water Glucose + Oxygen The light reaction take place in the thylakoid membranes and convert light energy into chemical energy in the form of ATP and NADPH. The light reaction take place in the thylakoid membranes and convert light energy into chemical energy in the form of ATP and NADPH. The light reactions use the reactant H 2 O and release the product O 2. The light reactions use the reactant H 2 O and release the product O 2. The Calvin Cycle takes place in the stroma and uses ATP and NADPH to convert CO 2 to C 6 H 12 O 6. The Calvin Cycle takes place in the stroma and uses ATP and NADPH to convert CO 2 to C 6 H 12 O 6.

18 Summary of Photosynthesis Photosynthesis is the first step in the flow of energy through an ecosystem. Photosynthesis is the first step in the flow of energy through an ecosystem. Photosynthesis is the ultimate source of all the food that you eat and all the oxygen that you breathe. Photosynthesis is the ultimate source of all the food that you eat and all the oxygen that you breathe.

19 Concept 8.4: Photosynthesis has a global impact

20 I. The Carbon Cycle The Carbon Cycle is the process by which carbon moves from inorganic to organic compounds and back. The Carbon Cycle is the process by which carbon moves from inorganic to organic compounds and back. Through photosynthesis, producers convert inorganic CO 2 to organic compounds. (ex: sugar) Through photosynthesis, producers convert inorganic CO 2 to organic compounds. (ex: sugar) Cellular Respiration by both producers and consumers return the CO 2 to the atmosphere. Cellular Respiration by both producers and consumers return the CO 2 to the atmosphere. No other chemical process matches the output of photosynthesis. No other chemical process matches the output of photosynthesis. Earths plants and other photosynthetic organisms make up about 160 billion metric tons of organic material per year. Earths plants and other photosynthetic organisms make up about 160 billion metric tons of organic material per year.

21 II. Photosynthesis and Global Climate One organism may either produce or use a relatively small amount of CO 2, the total effect of all the organisms on Earth has a very large effect. One organism may either produce or use a relatively small amount of CO 2, the total effect of all the organisms on Earth has a very large effect. CO 2 only made up 0.03% of the Earths atmosphere before this century. CO 2 only made up 0.03% of the Earths atmosphere before this century. CO 2 traps heat from the sun that would have otherwise escaped back into space, this property is known as the Greenhouse Effect. CO 2 traps heat from the sun that would have otherwise escaped back into space, this property is known as the Greenhouse Effect.

22 Greenhouse Effect

23 Photosynthesis and Global Climate The greenhouse effect keeps the average temperature on Earth about 10 degrees warmer than it would be otherwise. The greenhouse effect keeps the average temperature on Earth about 10 degrees warmer than it would be otherwise. The amount of CO 2 in the atmosphere is rising with no end in sight. The amount of CO 2 in the atmosphere is rising with no end in sight.


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