Chapter 8 Cellular Energy Section 1: How Organisms Obtain Energy Section 2: Photosynthesis Section 3: Cellular Respiration Click on a lesson name to select.
Download ReportTranscript Chapter 8 Cellular Energy Section 1: How Organisms Obtain Energy Section 2: Photosynthesis Section 3: Cellular Respiration Click on a lesson name to select.
Chapter 8 Cellular Energy
Click on a lesson name to select.
Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy
Transformation of Energy
Energy
is the ability to do work.
Thermodynamics
is the study of the flow and transformation of energy in the universe.
Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy
Laws of Thermodynamics
First law —energy can be converted from one form to another, but it cannot be created nor destroyed.
Second law —energy cannot be converted without the loss of usable energy.
Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Autotrophs are organisms that make their own food.
Heterotrophs are organisms that need to ingest food to obtain energy.
Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy
Metabolism
All of the chemical reactions in a cell
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
Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy
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.
Chapter 8 Cellular Energy 8.2 Photosynthesis
Overview of Photosynthesis
Photosynthesis occurs in two phases.
Light-dependent reactions Light-independent reactions
Chapter 8 Cellular Energy 8.2 Photosynthesis
Phase One: Light Reactions
The absorption of light is the first step in photosynthesis.
Chloroplasts capture light energy.
Chapter 8 Cellular Energy 8.2 Photosynthesis
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 O 2 as a waste product.
Chapter 8 Cellular Energy 8.2 Photosynthesis
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.
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.
Visualizing Electron Transport
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 Cellular Energy 8.2 Photosynthesis
Six CO 2 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.
Rubisco
• Ribulose Biphosphate Carboxylase is an allosteric enzyme involved in photosynthesis in which oxygen and carbon dioxide compete for the same binding site. • If carbon dioxide levels are high, more carbon dioxide binds to rubisco and photosynthesis continues. • If oxygen levels are high, however, then oxygen binds to rubisco and produces carbon dioxide and ammonia. This is wasteful since no ATP or NADPH is formed.
Chapter 8 Cellular Energy 8.2 Photosynthesis
Alternative Pathways
C 4 plants There is an energetic cost: +2 ATP for each CO2 fixed (but essentially NO oxygenation) .Many of the C4 pathway enzymes are regulated by light (active in light). C4 pathway allows more efficient carbon fixation at
high temperatures
1) PEP carboxylase binds CO2 at very low conc, so stomata can partially close 2) photorespiration is very low, so no effect of higher [O2] at higher temps The C4 pathway is mostly found among tropical grasses (growing in warm, sunny environments). C4 plants
cannot
compete with C3 plants in moist, colder, and less sunny environments. Less than 1% of plant species use C4 photosynthesis.
Chapter 8 Cellular Energy 8.2 Photosynthesis
Alternative Pathways
C 4 plants
C4 Carbon Fixation
is a method some plants use to avoid the problems associated with rubisco and photorespiration. C4 plants carry out the light reactions of photosynthesis in the
mesophyll
other plants, but they carry out the light-independent reactions in the
bundle sheath cells
. The enzyme in the bundle sheath cells,
PEP carboxylase
, has a higher like affinity for grabbing carbon dioxide than rubisco. This gives C4 plants a better chance of survival in tightly packed areas where carbon dioxide may be limited even though less glucose is produced per photon of light energy. C4 plants
cannot
compete with C3 plants in moist, colder, and less sunny environments. Less than 1% of plant species use C4 photosynthesis.
Chapter 8 Cellular Energy 8.2 Photosynthesis
Alternative Pathways
CAM plants Plants that close their stomata during the day to reduce water loss and open them at night for carbon uptake. CAM plants cannot compete with C3 plants in a moist, cool environment, because closing stomata during the day is much less efficient. Some plants are facultative CAM plants, though. They can switch between C3 and CAM photosynthesis, depending on environmental conditions. Only about 3 to 4% of earth's plant species can be characterized as CAM plants.
Water use efficiencies for C3, C4, ad CAM plants:
• C3 = 400 to 500 g water lost / gram CO2 fixed • C4= 250 to 300 g water lost / gram CO2 fixed. • CAM = 50 to 100 g water lost / gram CO2 fixed.
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Overview of Cellular Respiration
Organisms obtain energy in a process called cellular respiration.
The equation for cellular respiration is the opposite of the equation for photosynthesis.
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Cellular respiration occurs in two main parts.
Glycolysis
Aerobic respiration
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Glycolysis
Glucose is broken down in the cytoplasm through the process of glycolysis.
Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Krebs Cycle
Glycolysis has a net result of two ATP and two pyruvate. 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.
Chapter 8 Cellular Energy 8.3 Cellular Respiration
The net yield from the Krebs cycle is six CO 2 molecules, two ATP, eight NADH, and two FADH 2 .
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Electron Transport
Final step in the breakdown of glucose Point at which ATP is produced Produces 24 ATP
Chapter 8 Cellular Energy 8.3 Cellular Respiration
Anaerobic Respiration
The anaerobic pathway that follows glycolysis Two main types Lactic acid fermentation Alcohol fermentation
Cellular Respiration
Chapter 8 Cellular Energy Chapter Resource Menu
Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com
Glencoe Biology
Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding lesson.
Chapter 8 Cellular Energy Chapter Diagnostic Questions
Which statement describes the law of conservation of energy? 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.
Chapter 8 Cellular Energy Chapter Diagnostic Questions
In which metabolic process are molecules broken down to produce carbon dioxide and water? A.
photosynthesis B.
cellular respiration C.
homeostasis D.
fermentation
Chapter 8 Cellular Energy Chapter Diagnostic Questions
At the end of the Calvin cycle, where is energy stored?
A.
NADPH B.
ATP C.
chloroplast D.
glucose
Chapter 8 Cellular Energy 8.1 Formative Questions
Which law of thermodynamics explains why the ladybug receives the least amount of usable energy?
Chapter 8 Cellular Energy 8.1 Formative Questions
A.
the first law of thermodynamics
B.
the second law of thermodynamics
Chapter 8 Cellular Energy 8.1 Formative Questions
True or False All of the energy from the food you eat comes from the sun.
Chapter 8 Cellular Energy 8.1 Formative Questions
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.
Chapter 8 Cellular Energy 8.1 Formative Questions
Why is adenosine triphosphate (ATP) such an important biological molecule? 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.
Chapter 8 Cellular Energy 8.2 Formative Questions
Where in the plant cell does photosynthesis take place?
A.
chloroplasts
B.
Golgi apparatus
C.
mitochondria
D.
vacuoles
Chapter 8 Cellular Energy 8.2 Formative Questions
Which range of wavelengths is reflected by chlorophylls
a
and
b
?
A.
400-500 nm B.
500-600 nm C.
600-700 nm
Chapter 8 Cellular Energy 8.2 Formative Questions
Which mechanism of photosynthesis uses the movement of hydrogen ions (H + ) across a concentration gradient to synthesize ATP?
A.
absorption B.
chemiosmosis C.
electron transport D.
C 2 pathway
Chapter 8 Cellular Energy 8.2 Formative Questions
How are the C 4 pathway and the CAM pathway an adaptive strategy for some plants?
A.
They accelerate photosynthesis.
B.
They release more oxygen.
C.
They help the plant conserve water.
D.
They reduce the requirement for ATP.
Chapter 8 Cellular Energy 8.3 Formative Questions
What is the overall purpose of cellular respiration?
A.
to make ATP B.
to process H 2 O C.
to store glucose D.
to deliver oxygen
Chapter 8 Cellular Energy 8.3 Formative Questions
Which represents the general sequence of cellular respiration?
A.
TCA cycle B.
glycolysis chemiosmosis Krebs cycle glycolysis electron transport C.
electron absorption phosphorylation D.
aerobic pathway fermentation catalysis anaerobic pathway
Chapter 8 Cellular Energy 8.3 Formative Questions
Which stage of cellular respiration is the anaerobic process?
A.
glycolysis
B.
Krebs cycle
C.
electron transport
Chapter 8 Cellular Energy 8.3 Formative Questions
Which molecule generated by the Krebs cycle is a waste product?
A.
CoA
B.
CO 2
C.
FADH 2
D.
NADH
Chapter 8 Cellular Energy Chapter Assessment Questions
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
Chapter 8 Cellular Energy Chapter Assessment Questions
During the Krebs cycle, pyruvate is broken down into what compound? A.
H 2 O B.
O 2 C.
CO D.
CO 2
Chapter 8 Cellular Energy Chapter Assessment Questions
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
Chapter 8 Cellular Energy Standardized Test Practice
Which metabolic process is photosynthesis?
A B
Chapter 8 Cellular Energy Standardized Test Practice
At the beginning of photosynthesis, which molecule is split to produce oxygen (O 2 ) as a waste product?
A.
CO 2 B.
H 2 O C.
D.
C 6 H 12 O 3-PGA 6
Chapter 8 Cellular Energy Standardized Test Practice
Which molecule helps provide the energy that drives this cycle?
A.
3-PGA B.
CO 2 C.
NADPH D.
rubisco
Chapter 8 Cellular Energy Standardized Test Practice
Which product of the Calvin cycle is used for the production of glucose and other organic compounds?
A.
ADP B.
CO 2 C.
G3P D.
NADP +
Chapter 8 Cellular Energy Standardized Test Practice
What is the final step of cellular respiration?
A.
O 2 and H + form H 2 O.
B.
Electrons and H 2 O generate ATP.
C.
D.
C 6 H 12 O6 is broken down into CO NADH and FADH 2 gain electrons.
2 .
Chapter 8 Cellular Energy Standardized Test Practice
What prevents pyruvate from entering the Krebs cycle and instead results in this pathway?
A.
a buildup of CO 2 B.
a lack of oxygen C.
an excess of glucose D.
an increased demand for ATP
Chapter 8 Cellular Energy Standardized Test Practice
Which is
not
a process that occurs in both cellular respiration and glycolysis?
A.
chemiosmosis B.
electron transport C.
glycolysis D.
production of G3P
Chapter 8 Cellular Energy Glencoe Biology Transparencies
Chapter 8 Cellular Energy Image Bank
Chapter 8 Cellular Energy Vocabulary
Section 1
energy thermodynamics metabolism Photosynthesis cellular respiration adenosine triphosphate (ATP)
Chapter 8 Cellular Energy Vocabulary
Section 2
thylakoid granum stroma pigment NADP + Calvin cycle rubisco
Chapter 8 Cellular Energy Vocabulary
Section 3
anaerobic process aerobic respiration aerobic process glycolysis Krebs cycle fermentation
Chapter 8 Cellular Energy Animation
Visualizing Electron Transport