Author: Biology Junction Team

PCC Biochemistry

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PCC Biochemistry
 

True/False
Indicate whether the statement is true or false. Write  + for true and  0 for false.
 1.
Atoms have a positive charge.
 2.
An element is made up of more than one kind of atom.
 3.
Hydrogen and oxygen atoms have an equal number of electrons.
 4.
A molecule is an atom that has gained or lost an electron.
 5.
An atom that gains or loses one or more electrons is called an ion.
 6.
An atom with more electrons than protons has a positive charge.
 7.
Ionic bonds form between two negatively charged particles.
 8.
A covalent bond forms between two atoms that share electrons to form a molecule.
 9.
Adhesion is an attraction between different substances.
 10.
The ability of water to retain heat helps cells maintain homeostasis.
 11.
Nonpolar molecules dissolve well in water.
 12.
Water molecules attract nonpolar molecules such as oil.
 13.
Organic compounds contain carbon atoms that are covalently bonded to other elements—typically hydrogen, oxygen, and other carbon atoms.
 14.
A nucleotide has four parts.
 15.
RNA is made up of a double strand of nucleotides.
 16.
DNA stores hereditary information that can be used to make proteins.
 17.
When cells break down food, the energy from the food is temporarily stored as ATP.
 18.
The amount of energy needed to cause a chemical reaction to start is called activation energy.
 19.
Without enzymes, chemical reactions necessary for life would not occur at a rate sufficient to sustain life.
 20.
Enzymes speed up a chemical reaction by increasing the activation energy of the reaction.
 21.
When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is increased.
 22.
Chemical reactions that occur in cells are called biochemical reactions.
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 23.
Atoms are composed of
a.
 protons.
c.
 electrons.
b.
 neutrons.
d.
 All of the above
 24.
The electrons of an atom
a.
 are found in the nucleus along with the protons.
b.
 occupy the space surrounding the nucleus.
c.
 have a positive charge.
d.
 are attached to the positive charge of neutrons.
 25.
The smallest particle of matter that can retain the chemical properties of carbon is a(n)
a.
 carbon molecule.
c.
 carbon atom.
b.
 carbon macromolecule.
d.
 element.
 26.
A substance that is composed of only one type of atom is called a(n)
a.
 nucleus.
c.
 element.
b.
 cell.
d.
 molecule.
 27.
All matter is composed of
a.
 cells.
c.
 atoms.
b.
 molecules.
d.
 carbon.
 28.
A molecule that has a partial positive charge on one side and a partial negative charge on the other side is called a
a.
 nonpolar molecule.
c.
 charged molecule.
b.
 polar molecule.
d.
 bipolar molecule.
 29.
A chemical formula shows the
a.
 kinds of bonds found in the molecule.
b.
 kinds of bonds found in the compound.
c.
 kinds of elements found in the compound.
d.
 arrangement of the elements found in the compound.
 30.
Ionic bonds form between molecules that have
a.
 opposite charges.
c.
 no charges.
b.
 the same charge.
d.
 neutral charges.
 31.
The bond formed when two atoms share a pair of electrons is called a(n)
a.
 hydrogen bond.
c.
 covalent bond.
b.
 ionic bond.
d.
 water bond.
 32.
Sharing of electrons in the outer energy levels of two atoms
a.
 results in ion formation.
b.
 occurs in covalent bonds.
c.
 only occurs if both are atoms of the same element.
d.
 is found only among carbon atoms.
 33.
Water is important to life because it
a.
 surrounds all cells.
b.
 is found inside cells.
c.
 influences the shape of the cell membrane.
d.
 All of the above
 34.
Nonpolar molecules have
a.
 no negative or positive poles.
c.
 only a negative pole.
b.
 both negative and positive poles.
d.
 only a positive pole.
 35.
When placed in the same container, oil and water do not mix because
a.
 they are both polar.
c.
 they are both nonpolar.
b.
 water is polar and oil is nonpolar.
d.
 water is nonpolar and oil is polar.
 36.
Due to the polarity of water, compounds that dissolve best in water contain
a.
 nonpolar bonds.
c.
 polar bonds.
b.
 ionic bonds.
d.
 Both (b) and (c)
 37.
Water is a polar molecule because
a.
 it contains two hydrogen atoms for each oxygen atom.
b.
 it has a charge.
c.
 different parts of the molecule have slightly different charges.
d.
 it does not have a charge.
 38.
Acidic solutions have a pH that is
a.
 less than 7.
c.
 a negative number.
b.
 between 7 and 14.
d.
 more than 7.
 39.
Hydrogen ions, H+, react with hydroxide ions, OH-, to form
a.
 water.
c.
 a base.
b.
 an acid.
d.
 None of the above
 40.
Which of the following is not an organic macromolecule?
a.
 carbohydrate
c.
 lipid
b.
 ice
d.
 nucleic acid
 41.
All organic compounds contain the element
a.
 carbon.
c.
 calcium.
b.
 nitrogen.
d.
 sodium.
 42.
Which of the following organic molecules are classified as carbohydrates?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 43.
Polysaccharides are
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 unsaturated fats.
 44.
Lipids are
a.
 polar molecules.
c.
 water soluble.
b.
 similar to water molecules.
d.
 nonpolar molecules.
 45.
Which of the following organic molecules are most closely related to proteins?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 46.
Long chains of amino acids are found in
a.
 carbohydrates.
c.
 proteins.
b.
 lipids.
d.
 sugars.
 47.
All of the following are examples of lipids except
a.
 saturated fats.
c.
 cholesterol.
b.
 starch.
d.
 earwax.
 48.
Lipids are soluble in
a.
 water.
c.
 oil.
b.
 salt water.
d.
 All of the above
 49.
Which organic molecules below are most closely related to lipids?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 50.
Which of the following organic molecules are most closely related to nucleic acids?
a.
 amino acids
c.
 nucleotides
b.
 fatty acids
d.
 sugars
 51.
Which of the following is a carbohydrate?
a.
 DNA
c.
 wax
b.
 insulin
d.
 sucrose
 52.
Carbohydrates and lipids have many carbon-hydrogen bonds; therefore, they both
a.
 store energy in these bonds.
c.
 dissolve only in vinegar.
b.
 are easily dissolved in water.
d.
 exist only in cells of plants.
nar001-1.jpg
nar001-2.jpg
Molecule A
Molecule B
 53.
Refer to the illustration above. Molecules like Molecule B are found in
a.
 carbohydrates.
c.
 nucleic acids.
b.
 lipids.
d.
 proteins.
 54.
Liquid fats called oils contain
a.
 mostly unsaturated fatty acids.
c.
 many glucose molecules.
b.
 mostly saturated fatty acids.
d.
 amino acids.
 55.
Animals store glucose in the form of
a.
 cellulose.
c.
 wax.
b.
 glycogen.
d.
 lipids.
 56.
The shape of a protein is primarily determined by
a.
 the type and sequence of its amino acids.
b.
 its size.
c.
 its cell location.
d.
 None of the above
 57.
The two types of nucleic acids are
a.
 chlorophyll and retinal.
c.
 lipids and sugars.
b.
 DNA and RNA.
d.
 glucose and glycogen.
 58.
DNA stores
a.
 fat.
c.
 protein.
b.
 carbohydrates.
d.
 heredity information.
 59.
The two strands of a DNA molecule are held together by
a.
 ionic bonds.
c.
 hydrogen bonds.
b.
 covalent bonds.
d.
 None of the above
 60.
A molecule shaped like a spiral staircase (double helix) is typical of
a.
 deoxyribonucleic acid.
c.
 lipids.
b.
 ribonucleic acid.
d.
 carbohydrates.
 61.
ATP (adenosine triphosphate) stores energy for cells to use in the bonds between its
a.
 amino acids.
c.
 nucleotides.
b.
 carbon atoms.
d.
 phosphates.
nar002-1.jpg
 62.
Refer to the illustration above. Which graph illustrates what happens during an energy-releasing reaction?
a.
 Graph A
b.
 Graph B
c.
 both graphs because they each show a different stage of an energy releasing reaction
d.
 None of the above
 63.
Refer to the illustration above. Which graph illustrates a reaction during which energy is released?
a.
 Graph A
b.
 Graph B
c.
 both graphs because all chemical reactions release energy
d.
 None of the above
nar003-1.jpg
 64.
Refer to the illustration above. Which of the following statements regarding the graph is true?
a.
 Reaction 2 occurs faster than Reaction 3 because Reaction 2 requires more energy than Reaction 3.
b.
 The difference between the graphs shown for Reaction 2 and Reaction 3 is because of a difference in the activation energy of these reactions.
c.
 Reactant A contains more energy at the beginning of the reaction than product C has after the reaction.
d.
 All of the above
 65.
Refer to the illustration above. Reaction 3 in the graph
a.
 probably occurred in the presence of a catalyst.
b.
 requires more activation energy than Reaction 2.
c.
 is the same as Reaction 1, but faster.
d.
 is slower than Reaction 2.
 66.
The molecule on which an enzyme acts is called a(n)
a.
 active site.
c.
 organic molecule.
b.
 inactive site.
d.
 substrate.
 67.
An enzyme
a.
 is not used up when catalyzing a reaction.
b.
 lowers the activation energy of a reaction.
c.
 bonds with a substrate molecule at the enzyme’s active site.
d.
 All of the above
 68.
Which of the following conditions affects the function of enzymes?
a.
 pH
c.
 enzyme concentration
b.
 heat
d.
 All of the above
 69.
Reducing activation energy
a.
 is a violation of the laws of nature.
b.
 requires higher temperatures than those found within cells.
c.
 occurs only when reactants are quickly added to the reaction mixture.
d.
 is accomplished by the action of catalysts on reactants.
 70.
Enzymes
a.
 are able to heat up molecules so that they can react.
b.
 always provide carbon dioxide for chemical reactions.
c.
 are biological catalysts.
d.
 absorb excess heat so that reactions occur at low temperatures.
 71.
A cell contains
a.
 thousands of different kinds of enzymes, each promoting a different chemical reaction.
b.
 one kind of enzyme that promotes thousands of different chemical reactions.
c.
 approximately 100 kinds of enzymes, each promoting a different chemical reaction.
d.
 one enzyme that promotes photosynthesis and one enzyme that promotes cellular respiration.
 72.
Amylase is a digestive enzyme that breaks down starch into
a.
 amino acids.
c.
 glycogen.
b.
 glucose.
d.
 cellulose.
 73.
The digestive enzyme pepsin works with hydrochloric acid to break down proteins in the stomach. Pepsin probably works best at a pH of
a.
 11.
c.
 3.
b.
 7.
d.
 Both (b) and (c).

 
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Transcription and Translation Tool

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Transcription and Translation Tool Converts DNA to RNA to protein.

DNA sequence:
RNA sequence:
 Protein sequence:
DNA (deoxyribonucleic acid)

  • a permanent copy of genetic information.
  • uses “T” instead of “U”
  • no 2′ OH group
  • more stable than RNA
  • lower error frequency during replication than RNA
RNA (ribonucleic acid)

  • messenger RNA (mRNA) is a temporary copy of the gene sequence in which protein is encoded.
Protein

  • consists of amino acids linked by aminoester (“peptide”) bonds.
  • most enzymes and many structural components of cells are made of proteins.

Study Guide Photosynthesis

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Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
Energy is required for a variety of life processes including
a.
 growth and reproduction.
b.
 movement.
c.
 transport of certain materials across cell membranes.
d.
 All of the above
 2.
Heterotrophs are organisms that can
a.
 produce food from inorganic molecules and sunlight.
b.
 survive without energy.
c.
 consume other organisms for energy.
d.
 carry out either photosynthesis or chemosynthesis.
 3.
Based on the cycle of photosynthesis and cellular respiration, one can say that the ultimate original source of energy for all living things on Earth is
a.
 glucose.
c.
 the sun.
b.
 water.
d.
 carbon dioxide.
 4.
The process whereby plants capture energy and make complex molecules is known as
a.
 homeostasis.
c.
 photosynthesis.
b.
 evolution.
d.
 development.
 5.
Suspended in the fluid stroma of chloroplasts are
a.
 organelles called eukaryotes.
b.
 numerous mitochondrial membranes.
c.
 small coins that provide energy.
d.
 stacks of thylakoids called grana.
 6.
photosynthesis : oxygen ::
a.
 respiration : darkness
b.
 light reactions : dark reactions
c.
 respiration : carbon dioxide
d.
 oxygen : carbon dioxide
 7.
biochemical pathway : reaction ::
a.
 barrier : wall
b.
 match : burn
c.
 theater : drama
d.
 assembly line : workers
 8.
light reactions : thylakoids ::
a.
 grana : thylakoids
b.
 grana : ATP
c.
 Calvin cycle : stroma
d.
 stroma : grana of chloroplast
 9.
The sun is considered the ultimate source of energy for life on Earth because
a.
 all organisms carry out photosynthesis.
b.
 all organisms carry out cellular respiration.
c.
 either photosynthetic organisms or organisms that have eaten them provide energy for all other organisms on Earth.
d.
 the sun heats Earth’s atmosphere.
 10.
The energy from the sun is converted into chemical energy in the form of organic compounds in a series of linked chemical reactions called a
a.
 photosynthetic reactant.
b.
 ATP generator.
c.
 chemical equation.
d.
 biochemical pathway.
 11.
The role of chlorophyll in photosynthesis is to
a.
 absorb light energy.
b.
 pass electrons to carotenoids.
c.
 split water molecules.
d.
 All of the above
 12.
When light strikes an object, the light may be
a.
 reflected.
c.
 transmitted.
b.
 absorbed.
d.
 All of the above
 13.
Chlorophyll is green because
a.
 it absorbs green wavelengths of light.
b.
 it absorbs blue and yellow wavelengths, which make green.
c.
 it reflects green wavelengths of light.
d.
 it transmits light and causes an optical illusion.
 14.
What happens when a chlorophyll molecule absorbs light?
a.
 Some of its electrons are raised to a higher energy level.
b.
 It disintegrates, giving off huge amounts of heat.
c.
 It glows, radiating green light and giving the plant a green appearance.
d.
 It attracts electrons from other molecules.
 15.
chloroplast : grana ::
a.
 photosystem : pigment molecules
b.
 chlorophyll : pigments
c.
 thylakoids : photosynthesis
d.
 chlorophyll : green
 16.
When electrons of a chlorophyll molecule are raised to a higher energy level,
a.
 they become a particle of light.
b.
 they form a glucose bond.
c.
 they enter an electron transport chain.
d.
 they enter the Calvin cycle.
 17.
NADP+ is important in photosynthesis because it
a.
 becomes oxidized to form NADP.
b.
 is needed to form chlorophyll.
c.
 provides additional oxygen atoms.
d.
 provides protons and electrons for some reactions.
 18.
The electrons of photosystem I
a.
 are eventually replaced by electrons from photosystem II.
b.
 attach to water molecules during the light reaction.
c.
 are at the end of the electron transport chain.
d.
 are absorbed by oxygen molecules to form water.
 19.
The source of oxygen produced during photosynthesis is
a.
 carbon dioxide.
c.
 chlorophyll.
b.
 water.
d.
 glucose.
 20.
The major atmospheric byproduct of photosynthesis is
a.
 nitrogen.
c.
 water.
b.
 carbon dioxide.
d.
 oxygen.
 21.
During the Calvin cycle, carbon-containing molecules are produced from
a.
 carbon atoms from ATP.
b.
 carbon atoms, hydrogen atoms, and oxygen atoms from glucose.
c.
 carbon atoms from carbon dioxide in the air and hydrogen atoms from water.
d.
 carbon atoms from carbon dioxide in the air and hydrogen atoms from NADPH.
 22.
Which of the following processes occurs in the thylakoid membrane and converts captured light energy into chemical energy?
a.
 the Calvin cycle
c.
 light absorption
b.
 ATP synthase
d.
 chemiosmosis
 23.
Chemiosmosis in the thylakoid membrane is directly responsible for
a.
 adding protons to NADP+.
b.
 providing the energy to produce ATP molecules.
c.
 producing ATP-synthetase.
d.
 generating glucose molecules.
 24.
At the thylakoid membrane,
a.
 electrons return to their original energy levels.
b.
 electrons are pushed out of the thylakoid.
c.
 energy from electrons is used to make glucose.
d.
 the thylakoid bursts, releasing energy.
 25.
Products of the light reactions of photosynthesis that provide energy for the Calvin cycle are
a.
 oxygen and ATP.
c.
 ATP and NADPH.
b.
 water and oxygen.
d.
 oxygen and NADPH.
 26.
The Calvin cycle of photosynthesis
a.
 requires ATP and NADPH.
b.
 can occur in both light and dark conditions.
c.
 generates glucose.
d.
 All of the above
 27.
The energy used in the Calvin cycle for the production of carbohydrate molecules comes from
a.
 ATP made during cellular respiration.
b.
 the Krebs cycle.
c.
 ATP made in the light reactions of photosynthesis.
d.
 CO2 absorbed during the last stage of photosynthesis.
 28.
During photosynthesis, the series of reactions that create the complex carbohydrates needed for energy and growth is called
a.
 the Calvin cycle.
b.
 the Krebs cycle.
c.
 the light reactions.
d.
 the electron transport chain.
 29.
All organic molecules contain carbon atoms that ultimately can be traced back in the food chain to
a.
 the bodies of heterotrophs.
b.
 carbon dioxide from the atmosphere.
c.
 water absorbed by plants.
d.
 the carbon that comes from the sun.
 30.
Which of the following can be produced from the products of the Calvin cycle?
a.
 carbohydrates
c.
 proteins
b.
 lipids
d.
 All of the above
 31.
C3, C4, and CAM plants differ from each other in that
a.
 C3 plants use the Calvin cycle for carbon fixation and C4 and CAM plants use different pathways for carbon fixation.
b.
 C3 plants have their stomata open during the day and C4 and CAM plants have their stomata open only at night.
c.
 C3 and C4 plants have their stomata open during the day and CAM plants have their stomata open only at night.
d.
 C3 plants use CO2 to form organic compounds and C4 and CAM plants use other sources of carbon.
nar001-1.jpg
 32.
Refer to the illustration above. Graph 1 demonstrates that the rate of photosynthesis
a.
 decreases in response to increasing light intensity.
b.
 increases indefinitely in response to increasing light intensity.
c.
 increases in response to increasing light intensity, but only to a certain point.
d.
 is unaffected by changes in light intensity.
 33.
Refer to the illustration above. Taken together, these graphs demonstrate that
a.
 photosynthesis is independent of environmental influences.
b.
 increases in light intensity cause increases in temperature.
c.
 as the rate of photosynthesis increases, the temperature of the plant eventually decreases.
d.
 the rate of photosynthesis is affected by changes in the plant’s environment.
 

Essay
 34.
Why do the cells of plant roots generally lack chloroplasts? Write your answer in the space below.
 35.
Define the terms autotroph and heterotroph. What types of organisms belong in each of these categories? Write your answer in the space below.

 
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Study Guide Cellular Respiration

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Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
When cells break down food molecules, energy
a.
 is released all at once.
b.
 is released entirely as body heat into the environment.
c.
 is temporarily stored in ATP molecules.
d.
 causes excitation of electrons in chlorophyll molecules.
 2.
ATP
a.
 contains five phosphate groups.
b.
 is essential for a cell to perform all the tasks necessary for life.
c.
 is found only in bacteria.
d.
 All of the above
 3.
A substance produced during photosynthesis that is used for completion of cellular respiration is
a.
 water.
c.
 NADPH.
b.
 ATP.
d.
 oxygen.
 4.
The process of cellular respiration
a.
 is performed only by organisms that are incapable of photosynthesis.
b.
 breaks down food molecules to release stored energy.
c.
 occurs before plants are able to carry out photosynthesis.
d.
 occurs only in animals.
 5.
cellular respiration : organic compounds ::
a.
 light bulb : glass
c.
 automobile : gasoline
b.
 trunk : clothing
d.
 country : nation
 6.
When glycolysis occurs,
a.
 a molecule of glucose is split.
b.
 two molecules of pyruvic acid are made.
c.
 some ATP is produced.
d.
 All of the above
 7.
The name of the process that takes place when organic compounds are broken down in the absence of oxygen is
a.
 respiration.
c.
 fermentation.
b.
 oxidation.
d.
 All of the above
 8.
When muscles are exercised extensively in the absence of sufficient oxygen,
a.
 a large amount of ATP is formed.
b.
 NADH molecules split.
c.
 lactic acid is produced.
d.
 cellular respiration ceases.
 9.
You have been growing some animal cells in culture. The cells grow well for several weeks, and then their growth slows down. You conduct some tests and determine that there is a lot of lactic acid in the culture fluid. Which of the following is the most likely explanation for the poor growth of the cells?
a.
 There is too much glucose in the culture fluid.
b.
 There is not enough glucose in the culture fluid.
c.
 There is too much oxygen in the culture fluid.
d.
 There is not enough oxygen in the culture fluid.
 10.
If the formation of a standard amount of ATP under certain conditions requires 12 kcal of energy and the complete oxidation of glucose yields 686 kcal of energy, how efficient is glycolysis at extracting energy from glucose?
a.
 1.7%
c.
 7.0%
b.
 3.5%
d.
 35%
 11.
Cellular respiration takes place in two stages:
a.
 glycolysis and fermentation.
b.
 Stage 1 and Stage 2 of photosynthesis.
c.
 glycolysis, then aerobic respiration.
d.
 aerobic respiration, then glycolysis.
 12.
In cellular respiration, a two-carbon molecule combines with a four-carbon molecule to form citric acid as part of
a.
 glycolysis.
b.
 carbon fixation.
c.
 the Krebs cycle.
d.
 the electron transport chain.
 13.
Acetyl coenzyme A
a.
 is formed from the breakdown of pyruvic acid.
b.
 enters the Krebs cycle.
c.
 can be used in synthesis of needed molecules.
d.
 All of the above
 14.
Glycolysis and aerobic respiration are different in that
a.
 glycolysis occurs on the cell membrane, while aerobic respiration occurs in mitochondria.
b.
 glycolysis occurs only in photosynthesis, while aerobic respiration is part of cellular respiration.
c.
 glycolysis occurs in the absence of oxygen, while aerobic respiration requires oxygen.
d.
 There is no difference; these terms are different names for the same process.
 15.
Which of the following is not formed during the Krebs cycle?
a.
 CO2
c.
 NADH
b.
 FADH2
d.
 NADPH
 16.
Which of the following is not part of cellular respiration?
a.
 electron transport
c.
 the Krebs cycle
b.
 glycolysis
d.
 the Calvin cycle
 17.
With oxygen present, the Krebs cycle and the electron transport chain
a.
 provide organisms an alternative to glycolysis.
b.
 produce most of the ATP needed for life.
c.
 break down glucose to produce carbon dioxide, water, and ATP.
d.
 All of the above
 18.
Water is an end product in
a.
 lactic acid formation.
c.
 the Krebs cycle.
b.
 fermentation.
d.
 the electron transport chain.
 19.
Krebs cycle : CO2 ::
a.
 glycolysis : glucose
b.
 acetyl CoA formation : O2
c.
 cellular respiration : O2
d.
 electron transport chain : ATP
 20.
ATP molecules produced during aerobic respiration
a.
 remain in the mitochondria in which they are formed.
b.
 are stored in chloroplasts of the same cell in which they are formed.
c.
 enter the cell’s cytoplasm through the membranes of the mitochondria in which they are formed.
d.
 are distributed by the bloodstream to all cells in the body.
 21.
At the end of the electron transport chain,
a.
 the electrons combine with oxygen and protons to form water.
b.
 the electrons are used in the formation of ethyl alcohol.
c.
 the electrons build up inside the mitochondria and diffuse back to a thylakoid.
d.
 None of the above
C6 H12O6 + 6O2 + ADP + P ® 6CO2 + 6 H2O + MOLECULE A
 22.
The process shown in the equation above begins in the cytoplasm of a cell and ends in the
a.
 cytoplasm.
c.
 endoplasmic reticulum.
b.
 mitochondria.
d.
 lysosome.
 23.
The equation above summarizes the process known as
a.
 photosynthesis.
c.
 cellular respiration.
b.
 fermentation.
d.
 protein breakdown.
 24.
The molecule referred to as “molecule A” in the equation above is
a.
 NADPH.
c.
 NADH.
b.
 ATP.
d.
 ADP.
 25.
When living cells break down molecules, energy is
a.
 stored as ADP.
c.
 released as heat.
b.
 stored as ATP.
d.
 Both b and c
 26.
Which of the following is the best explanation for the presence of both chloroplasts and mitochondria in plant cells?
a.
 In the light, plants are photosynthetic autotrophs. In the dark, they are heterotrophs.
b.
 If plants cannot produce enough ATP in the process of photosynthesis to meet their energy needs, they can produce it in aerobic respiration.
c.
 Sugars are produced in chloroplasts. These sugars can be stored in the plant for later use, converted to other chemicals, or broken down in aerobic respiration to yield ATP for the plant to use to meet its energy needs.
d.
 The leaves and sometimes the stems of plants contain chloroplasts, which produce ATP to meet the energy needs of these plant parts. The roots of plants contain mitochondria, which produce ATP to meet the energy needs of these plant parts.
 27.
In cellular respiration, the most energy is transferred during
a.
 glycolysis.
b.
 lactic acid fermentation.
c.
 the Krebs cycle.
d.
 the electron transport chain
 28.
Electrons are donated to the electron transport chain by
a.
 ATP and NADH.
c.
 ATP and NAD+.
b.
 FADH2 and NADH.
d.
 NAD+ and ATP.
 29.
If the formation of 38 molecules of ATP requires 266 kcal of energy and the complete oxidation of glucose yields 686 kcal of energy, how efficient is cellular respiration at extracting energy from glucose?
a.
 20%
c.
 25%
b.
 39%
d.
 100%
 

Completion
Complete each statement.
 30.
During fermentation, either ethyl alcohol and carbon dioxide or ____________________ is formed.
 31.
Of the maximum possible yield of 38 ATP molecules produced by the complete oxidation of one glucose molecule, ____________________ molecules of ATP are produced during glycolysis.
 32.
The Krebs cycle takes place in the _________________________.
 

Essay
 33.
The relationship between photosynthesis and cellular respiration is usually described as a cycle. Briefly explain. Write your answer in the space below.

 
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