copyright © by holt, rinehart and winston. all rights reserved. resourceschapter menu to view the...

Copyright © by Holt, Rinehart and Winston. All rights reserved.

ResourcesChapter menu

• To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.”

• To advance through the presentation, click the right-arrow key or the space bar.

• From the resources slide, click on any resource to see a presentation for that resource.

• From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation.

• You may exit the slide show at any time by pressing the Esc key.

How to Use This Presentation



Chapter Presentation

Transparencies Standardized Test Prep

Visual Concepts

Resources



Photosynthesis and Cellular RespirationChapter 5

Table of Contents

Section 1 Energy and Living Things

Section 2 Photosynthesis

Section 3 Cellular Respiration



Section 1 Energy and Living Things

Objectives

• Analyze the flow of energy through living systems.

• Compare the metabolism of autotrophs with that of heterotrophs.

• Describe the role of ATP in metabolism.

• Describe how energy is released from ATP.

Chapter 5



Energy in Living Systems• Directly or indirectly, almost all of the energy in living systems

needed for metabolism comes from the sun.

Section 1 Energy and Living ThingsChapter 5



Energy in Living Systems, continued

Building Molecules That Store Energy

• Metabolism involves either using energy to build molecules or breaking down molecules in which energy is stored.

• Photosynthesis is the process by which light energy is converted to chemical energy.

• Organisms that use energy from sunlight or from chemical bonds in inorganic substances to make organic compounds are called autotrophs.





Breaking Down Food for Energy

• The chemical energy in organic compounds can be transferred to other organic compounds or to organisms that consume food.

• Organisms that must get energy from food instead of directly from sunlight or inorganic substances are called Heterotrophs.

• Cellular respiration is a metabolic process similar to burning fuel.




Comparing Autotrophs and Heterotrophs





Transfer of Energy to ATP

• When cells break down food molecules, some of the energy in the molecules is released as heat. Much of the remaining energy is stored temporarily in molecules of ATP.

• Like money, ATP is a portable form of energy “currency” inside cells. ATP delivers energy wherever energy is needed in a cell.




Breakdown of Starch




ATP

• ATP (adenosine triphosphate) is a nucleotide with two extra energy-storing phosphate groups.

• Energy is released when the bonds that hold the phosphate groups together are broken.

• The removal of a phosphate group from ATP produces adenosine diphosphate, or ADP:

H2O + ATP ADP + P + energy




ATP Releases Energy




Comparing ADP with ATP




Section 2 Photosynthesis

Objectives

• Summarize how energy is captured from sunlight in the first stage of photosynthesis.

• Analyze the function of electron transport chains in the second stage of photosynthesis.

• Relate the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis.

• Identify three environmental factors that affect the rate of photosynthesis.

Chapter 5



Using the Energy in Sunlight

The Stages of Photosynthesis

• Stage 1 Energy is captured from sunlight.

• Stage 2 Light energy is converted to chemical energy, which is temporarily stored in ATP and the energy carrier molecule NADPH.

• Stage 3 The chemical energy stored in ATP and NADPH powers the formation of organic compounds, using carbon dioxide, CO2.

Section 2 PhotosynthesisChapter 5



Using the Energy in Sunlight

The Stages of Photosynthesis

• Photosynthesis can be summarized by the following equation:

6CO2 + 6H2O C6H12O6 + 6O2

Carbon dioxide water sugars oxygen gas




Photosynthesis




Stage One: Absorption of Light Energy

• Sunlight contains a mixture of all the wavelengths (colors) of visible light. When sunlight passes through a prism, the prism separates the light into different colors.




Stage One: Absorption of Light Energy, continuedPigments

• How does a human eye or a leaf absorb light? These structures contain light-absorbing substances called pigments.

• Chlorophyll the primary pigment involved in photosynthesis, absorbs mostly blue and red light and reflects green and yellow light.

• Plants contain two types of chlorophyll, chlorophyll a and chlorophyll b.




Chlorophyll a and b




Stage One: Absorption of Light Energy, continuedPigments

• The pigments that produce yellow and orange fall leaf colors, as well as the colors of many fruits, vegetables, and flowers, are called carotenoids.

• Carotenoids absorb wavelengths of light different from those absorbed by chlorophyll, so having both pigments enables plants to absorb more light energy during photosynthesis.




Carotenoid




Spectrum of Light and Plant Pigments




Absorption Spectra of Photosynthetic Pigments




Stage One: Absorption of Light Energy, continued

Production of Oxygen

• Clusters of pigments are embedded in the membranes of disk-shaped structures called thylakoids.

• When light strikes a thylakoid in a chloroplast, energy is transferred to electrons in chlorophyll.

• This energy transfer causes the electrons to jump to a higher energy level. This is how plants first capture energy from sunlight.




Stage One: Absorption of Light Energy, continued

Production of Oxygen

• The excited electrons that leave chlorophyll molecules must be replaced by other electrons.

• Plants get these replacement electrons from water molecules, which are split by thylakoid.

• The oxygen atoms, O, from the disassembled water molecules combine to form oxygen gas, O2.




Chloroplast




Parts of a Chloroplast




Stage Two: Conversion of Light Energy

• Excited electrons that leave chlorophyll molecules are used to produce new molecules that temporarily store chemical energy.

• First an excited electron jumps to a nearby molecule in the thylakoid membrane. Then the electron is passed through a series of molecules along the thylakoid membrane.

• The series of molecules through which excited electrons are passed along a thylakoid membrane are called electron transport chains.




Stage Two: Conversion of Light Energy, continuedElectron Transport Chains

• While one electron transport chain provides energy used to make ATP, a second electron transport chain provides energy used to make NADPH.

• NADPH is an electron carrier that provides the high-energy electrons needed to make carbon-hydrogen bonds in the third stage of photosynthesis.

• In this second chain, excited electrons combine with hydrogen ions as well as an electron acceptor called NADP+, forming NADPH.




Electron Transport Chains of Photosynthesis




Electron Transport Train




Converting Light Energy to Chemical Energy




Stage Three: Storage of Energy

• In the third (final) stage of photosynthesis, carbon atoms from carbon dioxide in the atmosphere are used to make organic compounds in which chemical energy is stored.

• The transfer of carbon dioxide to organic compounds is called carbon dioxide fixation.




Stage Three: Storage of Energy, continuedCalvin Cycle

• The Calvin cycle is a series of enzyme-assisted chemical reactions that produces a three-carbon sugar:

Step 1 Each molecule of carbon dioxide is added to a five-carbon compound by an enzyme.

Step 2 The resulting compound splits into two three-carbon compounds. Phosphate groups and electrons are added to the compounds.

Step 3 One of the resulting three-carbon sugars is used to make organic energy-storing compounds.


Step 4 The other three-carbon sugars are used to regenerate the initial five-carbon compound, thereby completing the cycle.



Calvin Cycle




Stage Three: Storage of Energy, continued

Factors that Affect Photosynthesis

• Photosynthesis is directly affected by various environmental factors.

• In general, the rate of photosynthesis increases as light intensity increases until all the pigments are being used.

• Photosynthesis is most efficient within a certain range of temperatures.




Environmental Influences on Photosynthesis




Section 3 Cellular Respiration

Objectives

• Summarize how glucose is broken down in the first stage of cellular respiration.

• Describe how ATP is made in the second stage of cellular respiration.

• Identify the role of fermentation in the second stage of cellular respiration.

• Evaluate the importance of oxygen in aerobic respiration.

Chapter 5



Cellular Energy

• Oxygen in the air you breathe makes the production of ATP more efficient, although some ATP is made without oxygen.

• Metabolic processes that require oxygen are called aerobic.

• Metabolic processes that do not require oxygen are called anaerobic, which means “without air.

Section 3 Cellular RespirationChapter 5



Cellular Energy, continued

The Stages of Cellular Respiration

• Cellular respiration is the process cells use to harvest the energy in organic compounds, particularly glucose. The breakdown of glucose during cellular respiration can be summarized by the following equation:

C6H12O6 + 6O2 6CO2 + 6H2O + energyglucose oxygen gas carbon dioxide water ATP




Cellular Energy, continued

The Stages of Cellular Respiration

• Cellular respiration occurs in two stages:

Stage 1 Glucose is converted to pyruvate, producing a small amount of ATP and NADH.

Stage 2 When oxygen is present, pyruvate and NADH are used to make a large amount of ATP. When oxygen is not present, pyruvate is converted to either lactate or ethanol and carbon dioxide.




Cellular Respiration




Stage One: Breakdown of Glucose

Glycolysis

• In the first stage of cellular respiration, glucose is broken down in the cytoplasm during a process called glycolysis.

• As glucose is broken down, some of its hydrogen atoms are transferred to an electron acceptor called NAD+. This forms an electron carrier called NADH.




NAD+ and NADH




Stage One: Breakdown of Glucose, continuedGlycolysis

• Glycolysis occurs in four steps:

Step 1 Phosphate groups from two ATP molecules are transferred to a glucose molecule.

Step 2 The resulting six-carbon compound is broken down to two three-carbon compounds.

Step 3 Two NADH molecules are produced, and each compound gains one more phosphate group.

Step 4 Each three-carbon compound is converted to a three-carbon pyruvate, producing four ATP molecules in the process.




Glycolysis




Stage Two: Production of ATP

• When oxygen is present, pyruvate produced during glycolysis enters a mitochondrion and is converted to a two-carbon compound.

• This reaction produces one carbon dioxide molecule, one NADH molecule, and one two-carbon acetyl group.

• The acetyl group is attached to a molecule called coenzyme A (CoA), forming a compound called acetyl-CoA.




Stage Two: Production of ATP, continued

Krebs Cycle

• Acetyl-CoA enters a series of enzyme-assisted reactions called the Krebs cycle, which follows five steps:

Step 1 Acetyl-CoA combines with a four-carbon compound, forming a six-carbon compound and releasing coenzyme A.

Step 2 Carbon dioxide is released from the six-carbon compound, forming a five-carbon compound. Electrons are transferred to NAD+, making a molecule of NADH.





Krebs Cycle

Step 3 Carbon dioxide is released from the compound. A molecule of ATP and a molecule of NADH are made.

Step 4 The existing four-carbon compound is converted to a new four-carbon compound. Electrons are transferred to an electron acceptor called FAD, making a molecule of FADH2, another type of electron carrier.

Step 5 The new four-carbon compound is then converted to the four-carbon compound that began the cycle. Another molecule of NADH is produced.




Krebs Cycle




FAD and FADH2





Electron Transport Train

• In aerobic respiration, electrons donated by NADH and FADH2 pass through an electron transport chain.

• In eukaryotic cells, the electron transport chain is located in the inner membranes of mitochondria.

• At the end of the electron transport chain, hydrogen ions and spent electrons combine with oxygen molecules forming water molecules.




Electron Transport Chain of Aerobic Respiration




Respiration in the Absence of Oxygen

• When oxygen is not present, NAD+ is recycled in another way. Under anaerobic conditions, electrons carried by NADH are transferred to pyruvate produced during glycolysis.

• This process recycles NAD+ needed to continue making ATP through glycolysis.

• The recycling of NAD+ using an organic hydrogen acceptor is called fermentation.




Fermentation




Respiration in the Absence of Oxygen, continuedLactic Acid Fermentation

• In some organisms, a three-carbon pyruvate is converted to a three-carbon lactate through lactic acid fermentation.

• Fermentation enables glycolysis to continue producing ATP in muscles as long as the glucose supply lasts.




Respiration in the Absence of Oxygen, continuedAlcoholic Fermentation

• In some organisms, the three-carbon pyruvate is broken down to ethanol (ethyl alcohol), a two-carbon compound, through alcoholic fermentation.

• As in lactic acid fermentation, NAD+ is recycled, and glycolysis can continue to produce ATP.




Respiration in the Absence of Oxygen, continuedLactic Acid and Alcoholic Fermentation

• When oxygen is not present, cells recycle NAD+ through fermentation.




Respiration in the Absence of Oxygen, continuedProduction of ATP

• When oxygen is present, aerobic respiration occurs to produce ATP. When oxygen is not present, fermentation occurs instead.




Cellular Respiration Versus Fermentation




Comparing Aerobic and Anaerobic Respiration




Multiple Choice

The chart below shows data on photosynthesis in one type of plant. Use the chart to answer questions 1–3.

Standardized Test PrepChapter 5



Multiple Choice, continued

1. Which statement is supported by the data?

A. Photosynthesis does not occur at 0°C.

B. The optimum temperature for photosynthesis is approximately 46°C.

C. The rate of photosynthesis at 40°C is greater than the rate at 20°C.

D. The rate of photosynthesis increases as temperature increases from 25°C to 30°C.





2. At approximately what temperature is the plant producing oxygen at the greatest rate?

F. 0°C

G. 23°C

H. 46°C

J. 50°C





3. Data obtained from a different type of plant show a similar relationship between rate of photosynthesis and temperature, but the curve is shifted to the right. What environment would this plant be best adapted to?

A. Cold subarctic environment

B. Cool, wet environment

C. Mild, dry environment

D. Hot equatorial environment


copyright © by holt, rinehart and winston. all rights reserved. resourceschapter menu to view the...

Documents

resourceschapter menu

energy metabolism

chemical energy

light energy

flow of energy

remaining energy

continued transfer of

resourceschapter menu