Chapter 8 Cellular Energy

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Chapter 8 Cellular Energy

Section 1: How Organisms Obtain Energy

Section 2: Photosynthesis

Section 3: Cellular Respiration

Transformation of Energy

Energy is the ability to do work.

8.1 How Organisms Obtain Energy

Cellular Energy

Thermodynamics is the study of the flow and transformation of energy in the universe.

Chapter 8

Laws of Thermodynamics

First law—energy can be converted from one form to another, but it cannot be created nor destroyed.


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Second law—energy cannot be converted without the loss of usable energy.

Chapter 8

Autotrophs and Heterotrophs

Autotrophs are organisms that make their own food.


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Heterotrophs are organisms that need to ingest food to obtain energy.

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Metabolism

All of the chemical reactions in a cell


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Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell

Cellular respiration—organic molecules are broken down to release energy for use by the cell

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ATP: The Unit of Cellular Energy

ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.


Cellular EnergyChapter 8

ATP

Overview of Photosynthesis

Photosynthesis occurs in two phases.

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Light-dependent reactions

Light-independent reactions

8.2 Photosynthesis

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Phase One: Light Reactions

The absorption of light is the first step in photosynthesis.

Cellular Energy

Chloroplasts capture light energy.

8.2 Photosynthesis

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Electron Transport

Light energy excites electrons in photosystem II and also causes a water molecule to split, releasing an electron into the electron transport system, H+ into the thylakoid space, and O2 as a waste product.

Cellular Energy

8.2 Photosynthesis

Chapter 8

The excited electrons move from photosystem II to an electron-acceptor molecule in the thylakoid membrane.

The electron-acceptor molecule transfers the electrons along a series of electron-carriers to photosystem I.

Cellular Energy

8.2 Photosynthesis

Chapter 8

Cellular Energy

8.2 Photosynthesis

Photosystem I transfers the electrons to a protein called ferrodoxin.

Ferrodoxin transfers the electrons to the electron carrier NADP+, forming the energy-storing molecule NADPH.

Chapter 8


Cellular Energy

8.2 Photosynthesis

Phase Two: The Calvin Cycle

In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose.

Chapter 8


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8.2 Photosynthesis

Six CO2 molecules combine with six 5-carbon compounds to form twelve 3-carbon molecules called 3-PGA.

The chemical energy stored in ATP and NADPH is transferred to the 3-PGA molecules to form high-energy molecules called G3P.

Chapter 8

Cellular Energy

8.2 Photosynthesis

Two G3P molecules leave the cycle to be used for the production of glucose and other organic compounds.

An enzyme called rubisco converts the remaining ten G3P molecules into 5-carbon molecules called RuBP.

These molecules combine with new carbon dioxide molecules to continue the cycle.

Chapter 8

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8.2 Photosynthesis

Alternative Pathways

C4 plants

CAM plants

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Overview of Cellular Respiration

Organisms obtain energy in a process called cellular respiration.

8.3 Cellular Respiration

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The equation for cellular respiration is the opposite of the equation for photosynthesis.

Chapter 8


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Cellular respiration occurs in two main parts.

Glycolysis

Aerobic respiration

Chapter 8

Glycolysis

Glucose is broken down in the cytoplasm through the process of glycolysis.


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Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.

Chapter 8

Krebs Cycle

Glycolysis has a net result of two ATP and two pyruvate.


Cellular Energy

Most of the energy from the glucose is still contained in the pyruvate.

The series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

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The net yield from the Krebs cycle is six CO2 molecules, two ATP, eight NADH, and two FADH2.

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Electron Transport

Final step in the breakdown of glucose

Point at which ATP is produced

Produces 24 ATP

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Anaerobic Respiration

The anaerobic pathway that follows glycolysis

Two main types

Lactic acid fermentation

Alcohol fermentation

Cellular Respiration

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Cellular Energy

Chapter Resource Menu

Chapter Diagnostic Questions

Formative Test Questions

Chapter Assessment Questions

Standardized Test Practice

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Vocabulary

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Chapter 8


1. A2. B3. C4. D

CDQ 1

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A. Energy cannot be converted or destroyed.

B. Energy can be converted and destroyed.

C. Energy can be converted but not destroyed.

D. Energy can be destroyed but not converted.

Which statement describes the law of conservation of energy?

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Chapter 8

1. A2. B3. C4. D

CDQ 2

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Chapter 8

A. photosynthesis

B. cellular respiration

C. homeostasis

D. fermentation

In which metabolic process are molecules broken down to produce carbon dioxide and water?

1. A2. B3. C4. D

CDQ 3

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Chapter 8

A. NADPH

B. ATP

C. chloroplast

D. glucose

At the end of the Calvin cycle, where is energy stored?

1. A

2. B

FQ 1


Which law of thermodynamics explains why the ladybug receives the least amount of usable energy?

A. the first law of thermodynamics

B. the second law of thermodynamics

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8.1 Formative Questions

1. A

2. B

FQ 2


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All of the energy from the food you eat comes from the sun.

A. true

B. false

1. A

2. B

3. C

4. D

FQ 3



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Why is cellular respiration a catabolic pathway?

A. Energy is used to form

glucose and oxygen.

B. Energy is converted from

water to carbon dioxide.

C. Energy that is lost is

converted to thermal energy.

D. Energy is released by the

breakdown of molecules.

1. A

2. B

3. C

4. D

FQ 4



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A. It captures light energy from the sun.

B. It is produced in anabolic pathways.

C. It stores and releases chemical energy.

D. It converts mechanical energy to thermal energy.

Why is adenosine triphosphate (ATP) such an important biological molecule?

1. A

2. B

3. C

4. D

FQ 5


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A. chloroplasts

B. Golgi apparatus

C. mitochondria

D. vacuoles

Where in the plant cell does photosynthesis take place?


1. A

2. B

3. C

FQ 6



A. 400-500 nm

B. 500-600 nm

C. 600-700 nm

Which range of wavelengths is reflected by chlorophylls a and b?

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1. A

2. B

3. C

4. D

FQ 7



A. absorption

B. chemiosmosis

C. electron transport

D. C2 pathway

Which mechanism of photosynthesis uses the movement of hydrogen ions (H+) across a concentration gradient to synthesize ATP?

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1. A

2. B

3. C

4. D

FQ 8



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A. They accelerate photosynthesis.

B. They release more oxygen.

C. They help the plant conserve water.

D. They reduce the requirement for ATP.

How are the C4 pathway and the CAM pathway

an adaptive strategy for some plants?

1. A

2. B

3. C

4. D

FQ 9


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A. to make ATP

B. to process H2O

C. to store glucose

D. to deliver oxygen

What is the overall purpose of cellular respiration?


1. A

2. B

3. C

4. D

FQ 10


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Which represents the general sequence of cellular respiration?

A. TCA cycle chemiosmosis glycolysis

B. glycolysis Krebs cycle electron transport

C. electron absorption catalysis phosphorylation

D. aerobic pathway anaerobic pathway fermentation


1. A

2. B

3. C

FQ 11


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A. glycolysis

B. Krebs cycle

C. electron transport

Which stage of cellular respiration is the anaerobic process?


1. A

2. B

3. C

4. D

FQ 12


A. CoA

B. CO2

C. FADH2

D. NADH

Which molecule generated by the Krebs cycle is a waste product?

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1. A

2. B

3. C

4. D

CAQ 1


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Look at the following figure. Which part of the chloroplast is a sac-like membrane arranged in stacks?

A. grana

B. stroma

C. thylakoids

D. Golgi apparatus


1. A

2. B

3. C

4. D

CAQ 2


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During the Krebs cycle, pyruvate is broken down into what compound?

A. H2O

B. O2

C. CO

D. CO2

1. A

2. B

3. C

4. D

CAQ 3


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Look at the following figure. Which molecule is released when ATP becomes ADP?

A. phosphate group

B. water molecule

C. ribose sugar

D. energy cells

1. A

2. B

STP 1


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Which metabolic process is photosynthesis?

A

B


1. A

2. B

3. C

4. D

STP 2


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At the beginning of photosynthesis, which molecule is split to produce oxygen (O2) as

a waste product?

A. CO2

B. H2O

C. C6H12O6

D. 3-PGA

1. A

2. B

3. C

4. D

STP 3


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Which molecule helps provide the energy that drives this cycle?

A. 3-PGA

B. CO2

C. NADPH

D. rubisco

1. A

2. B

3. C

4. D

STP 4


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Which product of the Calvin cycle is used for the production of glucose and other organic compounds?

A. ADP

B. CO2

C. G3P

D. NADP+

1. A

2. B

3. C

4. D

STP 5


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What is the final step of cellular respiration?

A. O2 and H+ form H2O.

B. Electrons and H2O generate ATP.

C. C6H12O6 is broken down into CO2.

D. NADH and FADH2 gain electrons.

1. A

2. B

3. C

4. D

STP 6


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What prevents pyruvate from entering the Krebs cycle and instead results in this pathway?

A. a buildup of CO2

B. a lack of oxygen

C. an excess of glucose

D. an increased demand for ATP

1. A

2. B

3. C

4. D

STP 7


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Which is not a process that occurs in both cellular respiration and glycolysis?

A. chemiosmosis

B. electron transport

C. glycolysis

D. production of G3P

Cellular Energy

Glencoe Biology Transparencies

Chapter 8

Cellular Energy

Image Bank

Chapter 8

energy

thermodynamics

metabolism

Photosynthesis

cellular respiration

adenosine triphosphate (ATP)


Vocabulary

Section 1

thylakoid

granum

stroma

pigment

NADP+

Calvin cycle

rubisco


Vocabulary

Section 2

anaerobic process

aerobic respiration

aerobic process

glycolysis

Krebs cycle

fermentation


Vocabulary

Section 3

Cellular Energy

ATP

The Calvin Cycle

Visualizing Electron Transport

The Krebs Cycle (Citric Acid Cycle)

Animation

Chapter 8




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Chapter 8 Cellular Energy