Introduction- Chapter 7

Introduction- Chapter 7
_____________, algae, and certain prokaryotes convert light energy to __________energy and store the chemical energy in sugar, made from _______________and water. © 2012 Pearson Education, Inc. 1

7.1 Autotrophs are the producers of the biosphere
________________ make food through the process of photosynthesis, Photosynthesis in plants takes place in __________________, converts carbon dioxide and water into _____________molecules, and releases oxygen. Photoautotrophs use the energy of light to produce organic molecules. ____________________are prokaryotes that use inorganic chemicals as their energy source. Teaching Tips 1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they come across on a regular basis. The collective lists from your students can be surprisingly long and might help to build up your catalog of examples. 2. The evolution of chloroplasts from photosynthetic prokaryotes living inside of eukaryotic cells is discussed in Module If your students have not already read Chapter 4, consider discussing this theory of endosymbiosis. 3. Some students might think that the term producers applies to the production of oxygen by plants. In turn, they might think that consumers are organisms that use oxygen (which would include all aerobic organisms). Extra care may be needed to clarify the definitions of these frequently used terms. © 2012 Pearson Education, Inc. 2

7.1 Autotrophs are the producers of the biosphere
_________________are consumers that feed on plants or ________________, or decompose organic material. Teaching Tips 1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they come across on a regular basis. The collective lists from your students can be surprisingly long and might help to build up your catalog of examples. 2. The evolution of chloroplasts from photosynthetic prokaryotes living inside of eukaryotic cells is discussed in Module If your students have not already read Chapter 4, consider discussing this theory of endosymbiosis. 3. Some students might think that the term producers applies to the production of oxygen by plants. In turn, they might think that consumers are organisms that use oxygen (which would include all aerobic organisms). Extra care may be needed to clarify the definitions of these frequently used terms. © 2012 Pearson Education, Inc. 3

7.2 Photosynthesis occurs in chloroplasts in plant cells
____________are the major sites of photosynthesis in green plants. _______________ is an important light-absorbing __________in chloroplasts, is responsible for the _____________color of plants, and plays a central role in converting solar energy to chemical energy. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of plant roots, fish gills, and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. © 2012 Pearson Education, Inc. 4

Chloroplasts are concentrated in the cells of the _______________, the green tissue in the interior of the leaf. ____________are tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit. ________________in the leaf deliver water absorbed by roots. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of plant roots, fish gills, and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. © 2012 Pearson Education, Inc. 5

Chloroplasts consist of an envelope of __________membranes, which enclose an inner compartment filled with a thick fluid called __________________and contain a system of interconnected membranous sacs called ____________________. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of plant roots, fish gills, and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. © 2012 Pearson Education, Inc. 6

Thylakoids are often concentrated in stacks called _________and have an internal compartment called the thylakoid space. Thylakoid membranes also house much of the machinery that converts light energy to chemical energy. ____________________molecules are built into the thylakoid membrane and capture light energy. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of plant roots, fish gills, and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. © 2012 Pearson Education, Inc. 7

7.3 SCIENTIFIC DISCOVERY: Scientists traced the process of photosynthesis using isotopes
Scientists have known since the 1800s that plants produce O2. But does this oxygen come from carbon dioxide or water? For many years, it was assumed that ___________was extracted from ____________taken into the plant. However, later research using a heavy ___________of oxygen, 18O, confirmed that oxygen produced by photosynthesis comes from H2O. Student Misconceptions and Concerns Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants. Teaching Tips Many students do not realize that glucose is not the direct product of photosynthesis. Although glucose is often shown as a final product of photosynthesis, a three-carbon sugar is directly produced (G3P, as the authors note later in Module 7.10). A plant can use G3P to make many types of organic molecules, including glucose. © 2012 Pearson Education, Inc. 8

7.3 SCIENTIFIC DISCOVERY: Scientists traced the process of photosynthesis using isotopes
Experiment 1: 6 CO2  12 H2O → C6H12O6  6 H2O  6 O2 Experiment 2: 6 CO2  12 H2O → C6H12O6  6 H2O  6 O2 Reactants: Student Misconceptions and Concerns Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants. Teaching Tips Many students do not realize that glucose is not the direct product of photosynthesis. Although glucose is often shown as a final product of photosynthesis, a three-carbon sugar is directly produced (G3P, as the authors note later in Module 7.10). A plant can use G3P to make many types of organic molecules, including glucose. Products: © 2012 Pearson Education, Inc. 9

7.4 Photosynthesis is a redox process, as is cellular respiration
Photosynthesis is a __________(oxidation-reduction) process. ________becomes reduced to sugar as electrons along with hydrogen ions from water are added to it. ___________molecules are oxidized when they lose electrons along with hydrogen ions. Becomes reduced Teaching Tips In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. Becomes oxidized © 2012 Pearson Education, Inc. 10

7.4 Photosynthesis is a redox process, as is cellular respiration
In photosynthesis, ________________is captured by chlorophyll molecules to boost the energy of _________________, light energy is converted to ___________energy, and chemical energy is stored in the chemical bonds of ______________. Teaching Tips In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. © 2012 Pearson Education, Inc. 11

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH
Photosynthesis occurs in two metabolic stages. The _____________occur in the thylakoid membranes. In these reactions water is _________, providing a source of electrons and giving off oxygen as a by-product, ________is generated from ADP and a phosphate group, and light energy is absorbed by the chlorophyll molecules to drive the transfer of electrons and H+ from water to the electron acceptor __________+ reducing it to NADPH. ___________produced by the light reactions provides the electrons for reducing carbon in the Calvin cycle. Student Misconceptions and Concerns Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer, which notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates that water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to ultimately generate carbohydrates. © 2012 Pearson Education, Inc. 12

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH
The second stage is the _____________, which occurs in the stroma of the chloroplast. The Calvin cycle is a cyclic series of reactions that assembles ___________molecules using CO2 and the energy-rich products of the light reactions. During the Calvin cycle, CO2 is incorporated into organic compounds in a process called ___________________. After carbon fixation, __________of the cycle make sugars by further reducing the carbon compounds. The Calvin cycle is often called the dark reactions or light-_________________ reactions, because none of the steps requires light directly. Student Misconceptions and Concerns Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer, which notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates that water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to ultimately generate carbohydrates. © 2012 Pearson Education, Inc. 13

7.6 Visible radiation absorbed by pigments drives the light reactions
Sunlight contains energy called electromagnetic energy or electromagnetic radiation. Visible light is only a small part of the ____________ spectrum, the full range of electromagnetic wavelengths. Electromagnetic energy travels in waves, and the ______________is the distance between the crests of two adjacent waves. Light behaves as discrete packets of energy called photons. A ________________is a fixed quantity of light energy. The ____________the wavelength, the greater the energy. Student Misconceptions and Concerns 1. The authors note that electromagnetic energy travels through space in waves that are like ripples made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light, which exhibits the properties of waves and particles, may need to be discussed further, if students are to do more than just accept definitions. 2. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each might need to be explained. Teaching Tips Consider bringing a prism to class and demonstrating the spectrum of light. Depending on what you have available, it can be a dramatic reinforcement. © 2012 Pearson Education, Inc. 14

__________________ absorb light and are built into the thylakoid membrane. Plant pigments absorb some _________________of light and reflect or transmit other wavelengths. We see the color of the wavelengths that are transmitted. For example, chlorophyll transmits _______________wavelengths. Student Misconceptions and Concerns 1. The authors note that electromagnetic energy travels through space in waves that are like ripples made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light, which exhibits the properties of waves and particles, may need to be discussed further, if students are to do more than just accept definitions. 2. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each might need to be explained. Teaching Tips Consider bringing a prism to class and demonstrating the spectrum of light. Depending on what you have available, it can be a dramatic reinforcement. Animation: Light and Pigments © 2012 Pearson Education, Inc. 15

Chloroplasts contain __________different pigments, which absorb light of different wavelengths. _____________ absorbs blue-violet and red light and reflects green. Chlorophyll b absorbs blue and orange and reflects yellow-green. ___________________ broaden the spectrum of colors that can drive photosynthesis and provide __________, absorbing and dissipating excessive light energy that would otherwise damage chlorophyll or interact with oxygen to form reactive oxidative molecules. Student Misconceptions and Concerns 1. The authors note that electromagnetic energy travels through space in waves that are like ripples made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light, which exhibits the properties of waves and particles, may need to be discussed further, if students are to do more than just accept definitions. 2. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each might need to be explained. Teaching Tips Consider bringing a prism to class and demonstrating the spectrum of light. Depending on what you have available, it can be a dramatic reinforcement. © 2012 Pearson Education, Inc. 16

7.7 Photosystems capture solar energy
Pigments in chloroplasts absorb __________ (capturing solar power), which increases the potential energy of the pigment’s electrons and sends the electrons into an unstable state. These ____________electrons drop back down to their “___________,” and as they do, release their excess energy as heat. Student Misconceptions and Concerns Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths. Teaching Tips The authors discuss a phenomenon that most students have noticed: dark surfaces heat up faster in the sun than do lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat. © 2012 Pearson Education, Inc. 17

Within a _______________membrane, chlorophyll and other pigment molecules absorb ________________and transfer the energy to other pigment molecules. In the thylakoid membrane, chlorophyll molecules are organized along with other ___________and proteins into photosystems. Student Misconceptions and Concerns Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths. Teaching Tips The authors discuss a phenomenon that most students have noticed: dark surfaces heat up faster in the sun than do lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat. © 2012 Pearson Education, Inc. 18

A __________________consists of a number of light-harvesting complexes surrounding a reaction- center complex. A light-harvesting complex contains various pigment molecules bound to proteins. Collectively, the light-harvesting complexes function as a light-gathering _________________. Student Misconceptions and Concerns Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths. Teaching Tips The authors discuss a phenomenon that most students have noticed: dark surfaces heat up faster in the sun than do lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat. © 2012 Pearson Education, Inc. 19

The light energy is passed from molecule to molecule within the photosystem. Finally it reaches the ___________center where a ________________electron acceptor accepts these electrons and consequently becomes reduced. This _______________transfer of an electron from the reaction-center pigment to the primary electron acceptor is the first step in the transformation of light energy to chemical energy in the light reactions. Student Misconceptions and Concerns Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths. Teaching Tips The authors discuss a phenomenon that most students have noticed: dark surfaces heat up faster in the sun than do lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat. © 2012 Pearson Education, Inc. 20

___________types of photosystems (photosystem I and photosystem II) cooperate in the light reactions. Each type of photosystem has a characteristic reaction center. Photosystem II, which functions first, is called ___________ because its pigment absorbs light with a wavelength of 680 nm. Photosystem I, which functions second, is called ____________because it absorbs light with a wavelength of 700 nm. Student Misconceptions and Concerns Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths. Teaching Tips The authors discuss a phenomenon that most students have noticed: dark surfaces heat up faster in the sun than do lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat. © 2012 Pearson Education, Inc. 21

7.8 Two photosystems connected by an electron transport chain generate ATP and NADPH
In the light reactions, light energy is transformed into the chemical energy of ATP and __________. To accomplish this, electrons are removed from _____________, passed from photosystem II to photosystem I, and accepted by _____________+, reducing it to NADPH. Between the two photosystems, the electrons move down an electron transport chain and provide energy for the synthesis of ATP. Teaching Tips The authors develop a mechanical analogy for the energy levels and movement of electrons in the light reaction. Figure 7.8B equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. © 2012 Pearson Education, Inc. 22

7.8 Two photosystems connected by an electron transport chain generate ATP and NADPH
The products of the light reactions are __________________, ATP, and __________________. Teaching Tips The authors develop a mechanical analogy for the energy levels and movement of electrons in the light reaction. Figure 7.8B equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. © 2012 Pearson Education, Inc. 23

7.9 Chemiosmosis powers ATP synthesis in the light reactions
Interestingly, ______________is the mechanism that is involved in oxidative phosphorylation in mitochondria and generates ATP in chloroplasts. _____________is generated because the electron transport chain produces a concentration gradient of hydrogen ions across a membrane. Teaching Tips Module 7.9 notes the similarities between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. If your students have not already read or discussed chemiosmosis in mitochondria, consider assigning Modules 6.6 and 6.10 to show the similarities of these processes. (As noted in Module 7.2, the thylakoid space is analogous to the intermembrane space of mitochondria.) © 2012 Pearson Education, Inc. 24

7.9 Chemiosmosis powers ATP synthesis in the light reactions
In ____________________, using the initial energy input from light, the electron transport chain ___________H+ into the thylakoid space, and the resulting concentration gradient drives H+ back through ATP synthase, producing ATP. Teaching Tips Module 7.9 notes the similarities between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. If your students have not already read or discussed chemiosmosis in mitochondria, consider assigning Modules 6.6 and 6.10 to show the similarities of these processes. (As noted in Module 7.2, the thylakoid space is analogous to the intermembrane space of mitochondria.) © 2012 Pearson Education, Inc. 25

7.10 ATP and NADPH power sugar synthesis in the Calvin cycle
The __________makes sugar within a chloroplast. To produce sugar, the necessary ingredients are atmospheric ______________and ATP and NADPH generated by the light reactions. The Calvin cycle uses these three ingredients to produce an energy-rich, three-carbon sugar called glyceraldehyde-3-phosphate (________). A plant cell may then use G3P to make glucose and other organic molecules. Student Misconceptions and Concerns The terms light reactions and dark reactions can lead students to conclude that each set of reactions occurs at different times of the day. However, the Calvin cycle in most plants occurs during daylight, when NADPH and ATP from the light reactions are readily available. Teaching Tips Glucose is not the direct product of the Calvin cycle, as might be expected from the general equation for photosynthesis. Instead, as noted in the text, G3P is the main product. Clarify the diverse uses of G3P in the production of many important plant molecules for students. © 2012 Pearson Education, Inc. 26

7.10 ATP and NADPH power sugar synthesis in the Calvin cycle
The steps of the Calvin cycle include carbon fixation, ___________________, release of G3P, and regeneration of the starting molecule ribulose bisphosphate (_____________). Student Misconceptions and Concerns The terms light reactions and dark reactions can lead students to conclude that each set of reactions occurs at different times of the day. However, the Calvin cycle in most plants occurs during daylight, when NADPH and ATP from the light reactions are readily available. Teaching Tips Glucose is not the direct product of the Calvin cycle, as might be expected from the general equation for photosynthesis. Instead, as noted in the text, G3P is the main product. Clarify the diverse uses of G3P in the production of many important plant molecules for students. © 2012 Pearson Education, Inc. 27

7.11 EVOLUTION CONNECTION: Other methods of carbon fixation have evolved in hot, dry climates
Most plants use CO2 directly from the air, and carbon fixation occurs when the enzyme ______________adds CO2 to RuBP. Such plants are called ____________plants because the first product of carbon fixation is a three-carbon compound, ______________. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. © 2012 Pearson Education, Inc. 28

In hot and dry weather, C3 plants close their _____________to reduce water loss but prevent CO2 from entering the leaf and O2 from leaving. As O2 builds up in a leaf, __________adds O2 instead of CO2 to RuBP, and a two-carbon product of this reaction is then broken down in the cell. This process is called _______________because it occurs in the light, consumes O2, and releases CO2. But unlike cellular respiration, it uses ATP instead of producing it. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. © 2012 Pearson Education, Inc. 29

__________plants have evolved a means of carbon fixation that saves __________during photosynthesis while optimizing the Calvin cycle. C4 plants are so named because they first fix CO2 into a __________________compound. When the weather is hot and dry, C4 plants keep their stomata mostly closed, thus conserving water. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. © 2012 Pearson Education, Inc. 30

Another adaptation to hot and dry environments has evolved in the CAM plants, such as pineapples and cacti. ______________plants conserve water by opening their stomata and admitting CO2 only at night. CO2 is fixed into a four-carbon compound, which banks ______________at night and releases it to the Calvin cycle during the day. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. © 2012 Pearson Education, Inc. 31

7.12 Review: Photosynthesis uses light energy, carbon dioxide, and water to make organic molecules
About ____________of the carbohydrates made by photosynthesis are consumed as fuel for cellular respiration in the mitochondria of plant cells. Sugars also serve as the starting material for making other ____________molecules, such as proteins, lipids, and cellulose. Excess food made by plants is stockpiled as starch in ____________, tubers, ___________, and fruits. Student Misconceptions and Concerns Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. As noted in the text, nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria). Teaching Tips 1. Challenge students to explain how the energy in beef is ultimately derived from the sun. 2. The authors note that G3P is also used to produce cellulose, the most abundant organic molecule in a plant and probably on the surface of the Earth! © 2012 Pearson Education, Inc. 32

7.13 CONNECTION: Photosynthesis may moderate global climate change
The ______________effect operates on a global scale. Solar radiation includes visible light that penetrates the Earth’s atmosphere and warms the planet’s surface. Heat radiating from the warmed planet is absorbed by gases in the atmosphere, which then reflects some of the heat back to _________________. Without the warming of the ______________effect, the Earth would be much colder and most life as we know it could not exist. Student Misconceptions and Concerns 1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production. 2. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! © 2012 Pearson Education, Inc. 33

The gases in the atmosphere that absorb heat radiation are called greenhouse gases. These include _____________vapor, carbon dioxide, and ________________. Student Misconceptions and Concerns 1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production. 2. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! © 2012 Pearson Education, Inc. 34

Increasing concentrations of greenhouse gases have been linked to ____________climate change (also called global warming), a slow but steady rise in Earth’s surface temperature. Since 1850, the atmospheric concentration of CO2 has increased by about 40%, mostly due to the combustion of fossil fuels including _______________, oil, and ________________. Student Misconceptions and Concerns 1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production. 2. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! © 2012 Pearson Education, Inc. 35

The predicted consequences of continued warming include melting of ____________________, rising sea levels, extreme weather patterns, _______________________, increased extinction rates, and the spread of tropical __________________. Student Misconceptions and Concerns 1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production. 2. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! © 2012 Pearson Education, Inc. 36

Widespread ______________has aggravated the global warming problem by reducing an effective CO2 sink. Global warming caused by increasing CO2 levels may be reduced by limiting ______________________, reducing fossil fuel consumption, and growing _____________crops that remove CO2 from the atmosphere. Student Misconceptions and Concerns 1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production. 2. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! © 2012 Pearson Education, Inc. 37

7.14 SCIENTIFIC DISCOVERY: Scientific study of Earth’s ozone layer has global significance
Solar radiation converts O2 high in the atmosphere to ozone (O3), which shields organisms from damaging UV radiation. Industrial chemicals called _____have caused dangerous thinning of the ozone layer, but international restrictions on CFC use are allowing a slow recovery. Southern tip of South America Student Misconceptions and Concerns Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips 1. Consider an analogy between the ozone layer and sunscreen applied to the skin. The thinning of the ozone layer is like putting on less and less sunscreen. In both situations, more harmful UV light penetrates the layers and causes damage. 2. Frustration can overwhelm concerned students alarmed by the many problems addressed in this chapter. One way to address this is to provide meaningful ways for students to respond to this information (for example, changes in personal choices and voting). The Earth Day Network, is just one of many Internet sites devoted to positive action. Antarctica © 2012 Pearson Education, Inc. 38

Introduction- Chapter 7

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