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Wednesday, April 13, 2011

200+ Evolution Study Guide Answers

Level 11 Evolution Study Answers


            1.   ANS:  D                       

            2.   ANS:  E                       

            3.   ANS:  E                       

            4.   ANS:  B                       

            5.   ANS:  C                       

            6.   ANS:  C                       

            7.   ANS:  B                       

            8.   ANS:  A                       

            9.   ANS:  A          

           10.   ANS:  E          

           11.   ANS:  B                       

           12.   ANS:  D                       

           13.   ANS:  A                       

           14.   ANS:  A                       

           15.   ANS:  C                       

           16.   ANS:  B                       

           17.   ANS:  E                       

           18.   ANS:  C                       

           19.   ANS:  D                       

           20.   ANS:  C                       

           21.   ANS:  E                       

           22.   ANS:  B                       

           23.   ANS:  D                       

           24.   ANS:  A                       

           25.   ANS:  E                       

           26.   ANS:  E                       

           27.   ANS:  D                       

           28.   ANS:  A                       

           29.   ANS:  A                       

           30.   ANS:  C                       

           31.   ANS:  E                       

           32.   ANS:  D                       

           33.   ANS:  C                       

           34.   ANS:  B                       

           35.   ANS:  E                       

           36.   ANS:  B                       

           37.   ANS:  C                       

           38.   ANS:  D                       

           39.   ANS:  D                       

           40.   ANS:  B                       

           41.   ANS:  E                       

           42.   ANS:  B                       

           43.   ANS:  D                       

           44.   ANS:  C                       

           45.   ANS:  B                       

           46.   ANS:  E                       

           47.   ANS:  C                       

           48.   ANS:  E                       

           49.   ANS:  A                       

           50.   ANS:  D                       

           51.   ANS:  B          

           52.   ANS:  C          

           53.   ANS:  D          

           54.   ANS:  D          

           55.   ANS:  A          

           56.   ANS:  D          

           57.   ANS:  B                       

           58.   ANS:  D                       

           59.   ANS:  C                       

           60.   ANS:  E                       

           61.   ANS:  D                       

           62.   ANS:  C                       

           63.   ANS:  A                       

           64.   ANS:  A                       

           65.   ANS:  E                       

           66.   ANS:  C                       

           67.   ANS:  A                       

           68.   ANS:  C                       

           69.   ANS:  B                       

           70.   ANS:  C                       

           71.   ANS:  C                       

           72.   ANS:  B                       

           73.   ANS:  D                       

           74.   ANS:  B                       

           75.   ANS:  E                       

           76.   ANS:  E                       

           77.   ANS:  C                       

           78.   ANS:  E                       

           79.   ANS:  A                       

           80.   ANS:  A                       

           81.   ANS:  C                       

           82.   ANS:  D                       

           83.   ANS:  B                       

           84.   ANS:  A                       

           85.   ANS:  A                       

           86.   ANS:  E                       

           87.   ANS:  E                       

           88.   ANS:  E                       

           89.   ANS:  C                       

           90.   ANS:  E                       

           91.   ANS:  A                       

           92.   ANS:  D                       

           93.   ANS:  C                       

           94.   ANS:  D                       

           95.   ANS:  D                       

           96.   ANS:  D                       

           97.   ANS:  A                       

           98.   ANS:  A                       

           99.   ANS:  C                       

         100.   ANS:  C                       

         101.   ANS:  A                       

         102.   ANS:  E                       

         103.   ANS:  E                       

         104.   ANS:  D                       

         105.   ANS:  D                       

         106.   ANS:  E                       

         107.   ANS:  C                       

         108.   ANS:  B                       

         109.   ANS:  C                       

         110.   ANS:  D                       

         111.   ANS:  D                       

         112.   ANS:  C                       

         113.   ANS:  A                       

         114.   ANS:  B                       

         115.   ANS:  B                       

         116.   ANS:  B                       

         117.   ANS:  C                       

         118.   ANS:  C                       

         119.   ANS:  E                       

         120.   ANS:  B                       

         121.   ANS:  E                       

         122.   ANS:  A                       

         123.   ANS:  D          

         124.   ANS:  A          

         125.   ANS:  E          

         126.   ANS:  B          

         127.   ANS:  B          

         128.   ANS:  C                       

         129.   ANS:  A                       

         130.   ANS:  C                       

         131.   ANS:  A                       

         132.   ANS:  D                       

         133.   ANS:  A                       

         134.   ANS:  B                       

         135.   ANS:  D                       

         136.   ANS:  A                       

         137.   ANS:  C                       

         138.   ANS:  A                       

         139.   ANS:  D                       

         140.   ANS:  E                       

         141.   ANS:  D                       

         142.   ANS:  B                       

         143.   ANS:  A                       

         144.   ANS:  C                       

         145.   ANS:  C                       

         146.   ANS:  E                       

         147.   ANS:  B                       

         148.   ANS:  E                       

         149.   ANS:  C                       

         150.   ANS:  D                       

         151.   ANS:  C                       

         152.   ANS:  A                       

         153.   ANS:  D                       

         154.   ANS:  B                       

         155.   ANS:  B                       

         156.   ANS:  D                       

         157.   ANS:  D                       

         158.   ANS:  B                       

         159.   ANS:  A                       

         160.   ANS:  A                       

         161.   ANS:  B                       

         162.   ANS:  C                       

         163.   ANS:  C                       

Thursday, April 7, 2011

Ch. 17 overview+notes

Chapter 17: Overview: The Flow of Genetic Information
The information content of DNA is in the form of specific sequences of nucleotides
The DNA inherited by an organism leads to specific traits by dictating the synthesis of proteins
Proteins are the links between genotype and phenotype
Gene expression, the process by which DNA directs protein synthesis, includes two stages: transcription and translation

Concept 17.1: Genes specify proteins via transcription and translation
How was the fundamental relationship between genes and proteins discovered?
Evidence from the Study of Metabolic Defects
In 1909, British physician Archibald Garrod first suggested that genes dictate phenotypes through enzymes that catalyze specific chemical reactions
He thought symptoms of an inherited disease reflect an inability to synthesize a certain enzyme
Linking genes to enzymes required understanding that cells synthesize and degrade molecules in a series of steps, a metabolic pathway
Nutritional Mutants in Neurospora: Scientific Inquiry
George Beadle and Edward Tatum exposed bread mold to X-rays, creating mutants that were unable to survive on minimal medium as a result of inability to synthesize certain molecules
Using crosses, they identified three classes of arginine-deficient mutants, each lacking a different enzyme necessary for synthesizing arginine
They developed a one gene–one enzyme hypothesis, which states that each gene dictates production of a specific enzyme

The Products of Gene Expression: A Developing Story
Some proteins aren’t enzymes, so researchers later revised the hypothesis: one gene–one protein
Many proteins are composed of several polypeptides, each of which has its own gene
Therefore, Beadle and Tatum’s hypothesis is now restated as the one gene–one polypeptide hypothesis
Note that it is common to refer to gene products as proteins rather than polypeptides
Basic Principles of Transcription and Translation
RNA is the intermediate between genes and the proteins for which they code
Transcription is the synthesis of RNA under the direction of DNA
Transcription produces messenger RNA (mRNA)
Translation is the synthesis of a polypeptide, which occurs under the direction of mRNA
Ribosomes are the sites of translation

In prokaryotes, mRNA produced by transcription is immediately translated without more processing
In a eukaryotic cell, the nuclear envelope separates transcription from translation
Eukaryotic RNA transcripts are modified through RNA processing to yield finished mRNA

A primary transcript is the initial RNA transcript from any gene
The central dogma is the concept that cells are governed by a cellular chain of command: DNA RNA protein

The Genetic Code
How are the instructions for assembling amino acids into proteins encoded into DNA?
There are 20 amino acids, but there are only four nucleotide bases in DNA
How many bases correspond to an amino acid?
Codons: Triplets of Bases
The flow of information from gene to protein is based on a triplet code: a series of nonoverlapping, three-nucleotide words
These triplets are the smallest units of uniform length that can code for all the amino acids
Example: AGT at a particular position on a DNA strand results in the placement of the amino acid serine at the corresponding position of the polypeptide to be produced

During transcription, one of the two DNA strands called the template strand provides a template for ordering the sequence of nucleotides in an RNA transcript
During translation, the mRNA base triplets, called codons, are read in the 5 to 3 direction
Each codon specifies the amino acid to be placed at the corresponding position along a polypeptide

Codons along an mRNA molecule are read by translation machinery in the 5 to 3 direction
Each codon specifies the addition of one of 20 amino acids


Cracking the Code
All 64 codons were deciphered by the mid-1960s
Of the 64 triplets, 61 code for amino acids; 3 triplets are “stop” signals to end translation
The genetic code is redundant but not ambiguous; no codon specifies more than one amino acid
Codons must be read in the correct reading frame (correct groupings) in order for the specified polypeptide to be produced

Evolution of the Genetic Code
The genetic code is nearly universal, shared by the simplest bacteria to the most complex animals
Genes can be transcribed and translated after being transplanted from one species to another


Concept 17.2: Transcription is the DNA-directed synthesis of RNA: a closer look
Transcription, the first stage of gene expression, can be examined in more detail
Molecular Components of Transcription
RNA synthesis is catalyzed by RNA polymerase, which pries the DNA strands apart and hooks together the RNA nucleotides
RNA synthesis follows the same base-pairing rules as DNA, except uracil substitutes for thymine

The DNA sequence where RNA polymerase attaches is called the promoter; in bacteria, the sequence signaling the end of transcription is called the terminator
The stretch of DNA that is transcribed is called a transcription unit



Synthesis of an RNA Transcript
The three stages of transcription:
Initiation
Elongation
Termination
RNA Polymerase Binding and Initiation of Transcription
Promoters signal the initiation of RNA synthesis
Transcription factors mediate the binding of RNA polymerase and the initiation of transcription
The completed assembly of transcription factors and RNA polymerase II bound to a promoter is called a transcription initiation complex
A promoter called a TATA box is crucial in forming the initiation complex in eukaryotes

Elongation of the RNA Strand
As RNA polymerase moves along the DNA, it untwists the double helix, 10 to 20 bases at a time
Transcription progresses at a rate of 40 nucleotides per second in eukaryotes
A gene can be transcribed simultaneously by several RNA polymerases
Termination of Transcription
The mechanisms of termination are different in bacteria and eukaryotes
In bacteria, the polymerase stops transcription at the end of the terminator
In eukaryotes, the polymerase continues transcription after the pre-mRNA is cleaved from the growing RNA chain; the polymerase eventually falls off the DNA
Concept 17.3: Eukaryotic cells modify RNA after transcription
Enzymes in the eukaryotic nucleus modify pre-mRNA before the genetic messages are dispatched to the cytoplasm
During RNA processing, both ends of the primary transcript are usually altered
Also, usually some interior parts of the molecule are cut out, and the other parts spliced together
Alteration of mRNA Ends
Each end of a pre-mRNA molecule is modified in a particular way:
The 5 end receives a modified nucleotide 5 cap
The 3 end gets a poly-A tail
These modifications share several functions:
They seem to facilitate the export of mRNA
They protect mRNA from hydrolytic enzymes
They help ribosomes attach to the 5 end

Split Genes and RNA Splicing
Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that lie between coding regions
These noncoding regions are called intervening sequences, or introns
The other regions are called exons because they are eventually expressed, usually translated into amino acid sequences
RNA splicing removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence


In some cases, RNA splicing is carried out by spliceosomes
Spliceosomes consist of a variety of proteins and several small nuclear ribonucleoproteins (snRNPs) that recognize the splice sites



Ribozymes
Ribozymes are catalytic RNA molecules that function as enzymes and can splice RNA
The discovery of ribozymes rendered obsolete the belief that all biological catalysts were proteins

Three properties of RNA enable it to function as an enzyme
It can form a three-dimensional structure because of its ability to base pair with itself
Some bases in RNA contain functional groups
RNA may hydrogen-bond with other nucleic acid molecules

The Functional and Evolutionary Importance of Introns
Some genes can encode more than one kind of polypeptide, depending on which segments are treated as exons during RNA splicing
Such variations are called alternative RNA splicing
Because of alternative splicing, the number of different proteins an organism can produce is much greater than its number of genes

Proteins often have a modular architecture consisting of discrete regions called domains
In many cases, different exons code for the different domains in a protein
Exon shuffling may result in the evolution of new proteins

Concept 17.4: Translation is the RNA-directed synthesis of a polypeptide: a closer look
The translation of mRNA to protein can be examined in more detail
Molecular Components of Translation
A cell translates an mRNA message into protein with the help of transfer RNA (tRNA)
Molecules of tRNA are not identical:
Each carries a specific amino acid on one end
Each has an anticodon on the other end; the anticodon base-pairs with a complementary codon on mRNA

The Structure and Function of Transfer RNA
A tRNA molecule consists of a single RNA strand that is only about 80 nucleotides long
Flattened into one plane to reveal its base pairing, a tRNA molecule looks like a cloverleaf



Because of hydrogen bonds, tRNA actually twists and folds into a three-dimensional molecule
tRNA is roughly L-shaped

Accurate translation requires two steps:
First: a correct match between a tRNA and an amino acid, done by the enzyme aminoacyl-tRNA synthetase
Second: a correct match between the tRNA anticodon and an mRNA codon
Flexible pairing at the third base of a codon is called wobble and allows some tRNAs to bind to more than one codon

Ribosomes
Ribosomes facilitate specific coupling of tRNA anticodons with mRNA codons in protein synthesis
The two ribosomal subunits (large and small) are made of proteins and ribosomal RNA (rRNA)


A ribosome has three binding sites for tRNA:
The P site holds the tRNA that carries the growing polypeptide chain
The A site holds the tRNA that carries the next amino acid to be added to the chain
The E site is the exit site, where discharged tRNAs leave the ribosome
Building a Polypeptide
The three stages of translation:
Initiation
Elongation
Termination
All three stages require protein “factors” that aid in the translation process

Ribosome Association and Initiation of Translation
The initiation stage of translation brings together mRNA, a tRNA with the first amino acid, and the two ribosomal subunits
First, a small ribosomal subunit binds with mRNA and a special initiator tRNA
Then the small subunit moves along the mRNA until it reaches the start codon (AUG)
Proteins called initiation factors bring in the large subunit that completes the translation initiation complex

Elongation of the Polypeptide Chain
During the elongation stage, amino acids are added one by one to the preceding amino acid
Each addition involves proteins called elongation factors and occurs in three steps: codon recognition, peptide bond formation, and translocation

Termination of Translation
Termination occurs when a stop codon in the mRNA reaches the A site of the ribosome
The A site accepts a protein called a release factor
The release factor causes the addition of a water molecule instead of an amino acid
This reaction releases the polypeptide, and the translation assembly then comes apart

Polyribosomes
A number of ribosomes can translate a single mRNA simultaneously, forming a polyribosome (or polysome)
Polyribosomes enable a cell to make many copies of a polypeptide very quickly

Completing and Targeting the Functional Protein
Often translation is not sufficient to make a functional protein
Polypeptide chains are modified after translation
Completed proteins are targeted to specific sites in the cell
Protein Folding and Post-Translational Modifications
During and after synthesis, a polypeptide chain spontaneously coils and folds into its three-dimensional shape
Proteins may also require post-translational modifications before doing their job
Some polypeptides are activated by enzymes that cleave them
Other polypeptides come together to form the subunits of a protein
Targeting Polypeptides to Specific Locations
Two populations of ribosomes are evident in cells: free ribsomes (in the cytosol) and bound ribosomes (attached to the ER)
Free ribosomes mostly synthesize proteins that function in the cytosol
Bound ribosomes make proteins of the endomembrane system and proteins that are secreted from the cell
Ribosomes are identical and can switch from free to bound

Polypeptide synthesis always begins in the cytosol
Synthesis finishes in the cytosol unless the polypeptide signals the ribosome to attach to the ER
Polypeptides destined for the ER or for secretion are marked by a signal peptide

A signal-recognition particle (SRP) binds to the signal peptide
The SRP brings the signal peptide and its ribosome to the ER

Concept 17.5: Point mutations can affect protein structure and function
Mutations are changes in the genetic material of a cell or virus
Point mutations are chemical changes in just one base pair of a gene
The change of a single nucleotide in a DNA template strand can lead to the production of an abnormal protein

Types of Point Mutations
Point mutations within a gene can be divided into two general categories
Base-pair substitutions
Base-pair insertions or deletions








Substitutions
A base-pair substitution replaces one nucleotide and its partner with another pair of nucleotides
Silent mutations have no effect on the amino acid produced by a codon because of redundancy in the genetic code
Missense mutations still code for an amino acid, but not necessarily the right amino acid
Nonsense mutations change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein
Insertions and Deletions
Insertions and deletions are additions or losses of nucleotide pairs in a gene
These mutations have a disastrous effect on the resulting protein more often than substitutions do
Insertion or deletion of nucleotides may alter the reading frame, producing a frameshift mutation
Mutagens
Spontaneous mutations can occur during DNA replication, recombination, or repair
Mutagens are physical or chemical agents that can cause mutations
Concept 17.6: While gene expression differs among the domains of life, the concept of a gene is universal
Archaea are prokaryotes, but share many features of gene expression with eukaryotes
Comparing Gene Expression in Bacteria, Archaea, and Eukarya
Bacteria and eukarya differ in their RNA polymerases, termination of transcription and ribosomes; archaea tend to resemble eukarya in these respects
Bacteria can simultaneously transcribe and translate the same gene
In eukarya, transcription and translation are separated by the nuclear envelope
In archaea, transcription and translation are likely coupled

What Is a Gene? Revisiting the Question
The idea of the gene itself is a unifying concept of life
We have considered a gene as:
A discrete unit of inheritance
A region of specific nucleotide sequence in a chromosome
A DNA sequence that codes for a specific polypeptide chain


In summary, a gene can be defined as a region of DNA that can be expressed to produce a final functional product, either a polypeptide or an RNA molecule





You should now be able to:
Describe the contributions made by Garrod, Beadle, and Tatum to our understanding of the relationship between genes and enzymes
Briefly explain how information flows from gene to protein
Compare transcription and translation in bacteria and eukaryotes
Explain what it means to say that the genetic code is redundant and unambiguous

Include the following terms in a description of transcription: mRNA, RNA polymerase, the promoter, the terminator, the transcription unit, initiation, elongation, termination, and introns
Include the following terms in a description of translation: tRNA, wobble, ribosomes, initiation, elongation, and termination

Good Online study recourses

1. By chapter number, this site has chapter quizzes.
http://www.hbwbiology.net/quizzes-ap-review-main.htm

2. Great site for studying. A warning however, to see the answers you must take the full (ofter 50+ questions) quiz. By chapter http://www.global-service-center.com/Biologyquizzes/BiologyTOC.html

3. Might help on Ch. 10 content. Google docs:
http://docs.google.com/viewer?a=v&q=cache:3_sXC-IA-_QJ:fd.valenciacc.edu/file/cdiercksen/chap10conceptskey.pdf+trace+movement+of+electrons+in+cyclic+electron+flow&hl=en&gl=us&pid=bl&srcid=ADGEEShGE6lVox0hl3IlGlBKagEecw8CHFrAzDQXCEhK15UQAQCUqvT6Jx8Kh0Z_32EfAYEPS2Xui0M9Ngegiz97J81lEmVwrAlW9m-ikOOzyTFbEEYZiMbyGb-V0kVKijLsZWoiZEeR&sig=AHIEtbTACZMophElB_X-FmXMeqzartAvfQ

4. Chapers 2 and 3 , some 10 and 14 as well as others http://www.angelfire.com/ak5/biosucks/
(Love the html ending!)

5. http://www.bio.miami.edu/~cmallery/150/tests/150ss05t2.pdf (Answers in red.)

Study Guide, Ch.8 (?) Metabolism

1)Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? 1) ___E____
A)catalysis B)anabolism C)dehydration D)metabolism E)catabolism

 (E is the correct answer for #1, given by  ___E____ . The rest of the questions do this as well)


2)Which of the following is a statement of the first law of thermodynamics? 2) __A_____
A)Energy cannot be transferred or transformed. B)The entropy of the universe is constant. C)Energy cannot be created or destroyed. D)The entropy of the universe is decreasing. E)Kinetic energy is stored energy that results from the specific arrangement of matter.

3)Whenever energy is transformed, there is always an increase in the 3) ___E____ A)free energy of the system. B)entropy of the system. C)enthalpy of the universe. D)free energy of the universe. E)entropy of the universe. 4)Which of the following is considered an open system? 4) ____A___ A)an organism B)a sealed terrarium C)liquid in a corked bottle D)food cooking in a pressure cooker 5)Why is ATP an important molecule in metabolism? 5) ____B___ A)Its terminal phosphate group contains a strong covalent bond that when hydrolyzed releases free energy. B)It provides energy coupling between exergonic and endergonic reactions. C)Its hydrolysis provides an input of free energy for exergonic reactions. D)Its terminal phosphate bond has higher energy than the other two. E)A, B, C, and D 6)Which of the following statements is (are) true about enzyme-catalyzed reactions? 6) ___B____ A)The free energy change of the reaction is opposite from the reaction in the absence of the enzyme. B)The reaction is faster than the same reaction in the absence of the enzyme. C)The reaction always goes in the direction toward chemical equilibrium. D)A and B only E)A, B, and C 7)How can one increase the rate of a chemical reaction? 7) ____B__ A)Decrease the concentration of the reactants. B)Add a catalyst. C)Increase the entropy of the reactants. D)Increase the activation energy needed. E)Cool the reactants. 8)Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in 8) ___ A ___ A)breaking the bond between glucose and fructose and forming new bonds from the atoms of water. B)bringing glucose and fructose together to form sucrose. C)utilization of water as a covalent bond is formed between glucose and fructose to form sucrase. D)the release of water from sucrose as the bond between glucose and fructose is broken. E)production of water from the sugar as bonds are broken between the glucose monomers. 9)Which of the following statements regarding enzymes is true? 9) __A_____ A)Enzymes decrease the free energy change of a reaction. B)Enzymes prevent changes in substrate concentrations. C)Enzymes change the direction of chemical reactions. D)Enzymes increase the rate of a reaction. E)Enzymes are permanently altered by the reactions they catalyze.
Refer to Figure 8.1 to answer the following questions. graphic(Fig0801.bmp) Figure 8.1 10)Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70°C or higher? 10) ____C__ A)curve 1 B)curve 2 C)curve 3 D)curve 4 E)curve 5 11)Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid? 11) ___D___ A)curve 1 B)curve 2 C)curve 3 D)curve 4 E)curve 5 12)Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? 12) ____B__ A)allosteric inhibition B)competitive inhibition C)denaturization of the enzyme D)insufficient cofactors E)saturation of the enzyme activity 13)Which of the following is true of enzymes? 13) _A_____ A)Enzymes increase the rate of chemical reaction by lowering activation energy barriers. B)Enzymes may require a nonprotein cofactor or ion for catalysis to take speed up more appreciably than if the enzymes act alone. C)Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D)Enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered. The following questions are based on the reaction A + B → C + D shown in Figure 8.2. graphic(Fig0802.bmp) Figure 8.2 14)Which of the following terms best describes the reaction? 14) __A____ A)exergonic B)endergonic C)allosteric D)anabolic E)nonspontaneous 15)Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend? 15) ____B__ A)the enzyme becoming too saturated because of the concentration of substrate B)the ability of an enzyme to form a template for holding and joining molecules C)the enzyme providing an appropriate microenvironment conducive to a reaction's occurrence D)the enzyme's ability to stretch reactants and move them toward a transition state E)the enzyme forming covalent bonds with the reactants 16)How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? 16) __A____ A)by changing the shape of a reactant B)by changing the free energy change of the reaction C)by acting as a coenzyme for the reaction D)by decreasing the activation energy of the reaction E)by binding at the active site of the enzyme The next questions are based on the following information.
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. 17)What is substance X? 17) ___E___ A)a coenzyme B)the product C)an allosteric inhibitor D)an intermediate E)a substrate 18)Substance A functions as 18) __D____ A)the substrate. B)an intermediate. C)a competitive inhibitor. D)an allosteric inhibitor. E)a coenzyme. 19)Some enzymatic regulation is allosteric. In such cases, which of the following would usually be found? 19) ___E___ A)feedback inhibition B)the need for cofactors C)an enzyme with more than one subunit D)cooperativity E)both activating and inhibitory activity 20)Among enzymes, kinases catalyze phosphorylation, while phosphatases catalyze removal of phosphate(s). A cell's use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved? 20) ______ A)a change in the optimal temperature at which a reaction will occur B)a change in the optimal pH at which a reaction will occur C)the change in a protein's charge leading to cleavage D)the change in a protein's charge leading to a conformational change E)the excision of one or more peptides 21)When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes 21) _D_____ A)reduced. B)dehydrogenated. C)hydrogenated. D)oxidized. E)an oxidizing agent. 22)Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy 22) __B____ A)CO2 is reduced and O2 is oxidized. B)C6H12O6 is oxidized and O2 is reduced. C)O2 is oxidized and H2O is reduced. D)O2 is reduced and CO2 is oxidized. E)C6H12O6 is reduced and CO2 is oxidized. 23)Starting with one molecule of glucose, the "net" products of glycolysis are 23) _A_____ A)2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O. B)6 CO2, 6 H2O, 2 ATP, and 2 pyruvate. C)2 NAD+, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O. D)6 CO2, 6 H2O, 36 ATP, and 2 citrate. E)2 FADH2, 2 pyruvate, 4 ATP, and 2 H2O. 24)In glycolysis, for each molecule of glucose oxidized to pyruvate 24) __C____ A)4 molecules of ATP are used and 2 molecules of ATP are produced. B)2 molecules of ATP are used and 6 molecules of ATP are produced. C)2 molecules of ATP are used and 4 molecules of ATP are produced. D)2 molecules of ATP are used and 2 molecules of ATP are produced. E)6 molecules of ATP are used and 6 molecules of ATP are produced. Use the following information to answer the next questions.
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. 25)These three steps result in the formation of 25) ____A__ A)acetyl CoA, NADH, H+, and CO2. B)acetyl CoA, O2, and ATP. C)acetyl CoA, NAD+, ATP, and CO2. D)acetyl CoA, FADH2, and CO2. E)acetyl CoA, FAD, H2, and CO2. 26)How does pyruvate enter the mitochondrion? 26) _E_____ A)diffusion B)through a pore C)through a channel D)facilitated diffusion E)active transport 27)During cellular respiration, acetyl CoA accumulates in which location? 27) ___E___ A)mitochondrial outer membrane B)mitochondrial inner membrane C)cytosol D)mitochondrial intermembrane space E)mitochondrial matrix 28)How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? 28) ____B__ A)8 B) 2 C) 4 D) 6 E) 10 Refer to Figure 9.2, showing the citric acid cycle, as a guide to answer the following questions. graphic(Figure9-2.bmp) Figure 9.2 29)How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle? 29) ___C___ A)60 B) 5 C) 10 D) 12 E) 2 30)Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation? 30) ___E___ A)24 B) 11 C) 12 D) 2 E) 1 31)How many reduced dinucleotides would be produced with four turns of the citric acid cycle? 31) __A____ A)4 FADH2 and 12 NADH B)4 FAD+ and 12 NAD+ C)2 FADH2 and 8 NADH D)1 FADH2 and 4 NADH E)1 FAD and 4 NAD+ 32)For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle, what is the total number of NADH + FADH2 molecules produced? 32) ___B___ A)10 B) 12 C) 4 D) 5 E) 6 33)During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? 33) __D____ A)NAD+ B)ADP + Pi C)ATP D)FADH2 E)NADH 34)Inside an active mitochondrion, most electrons follow which pathway? 34) __C____ A)citric acid cycle → FADH2 → electron transport chain → ATP B)electron transport chain → citric acid cycle → ATP → oxygen C)citric acid cycle → NADH → electron transport chain → oxygen D)pyruvate → citric acid cycle → ATP → NADH → oxygen E)glycolysis → NADH → oxidative phosphorylation → ATP → oxygen
35)Energy released by the electron transport chain is used to pump H+ ions into which location? 35) __B__ A)mitochondrial inner membrane B)mitochondrial intermembrane space C)mitochondrial outer membrane D)cytosol E)mitochondrial matrix 36)In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP? 36) ___E___ A)energy released from substrate-level phosphorylation B)No external source of energy is required because the reaction is exergonic. C)energy released as electrons flow through the electron transport system D)energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix E)energy released from movement of protons through ATP synthase 37)When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the 37) ___D___ A)reduction of NAD+. B)restoration of the Na+/K+ balance across the membrane. C)lowering of pH in the mitochondrial matrix. D)creation of a proton gradient. E)formation of ATP. 38)Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required? 38) ____C__ A)1 B) 12 C) 6 D) 2 E) 38 39)Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration? 39) ___B___ A)4 B) 76 C) 38 D) 15 E) 2 40)In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. What purpose must this serve? 40) ______ A)It allows for increased rate of glycolysis. B)It increases the surface for oxidative phosphoryation. C)It allows the liver cell to have fewer mitochondria. D)It allows for increased rate of the citric acid cycle. E)It increases the surface for substrate-level phosphorylation. graphic(Fig0903.bmp) Figure 9.3 41)The accompanying figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain? 41) ____A__ A)NADH, FADH2, and electrons B)oxygen, carbon dioxide, and water C)Oxygen and electrons D)NAD+ , FAD, and electrons E)NADH, FADH2, and protons 42)Which of the following most accurately describes what is happening along this chain? 42) ____C__ A)Energy of the electrons increases at each step. B)Molecules in the chain give up some of their potential energy. C)Each electron carrier alternates between being reduced and being oxidized. D)Chemiosmosis is coupled with electron transfer. E)ATP is generated at each step. 43)In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of 43) ___A___ A)ATP, CO2, and ethanol (ethyl alcohol). B)ATP, pyruvate, and acetyl CoA. C)ATP, pyruvate, and oxygen. D)ATP, CO2, and lactate. E)ATP, NADH, and pyruvate.
44)When muscle cells are oxygen deprived, the heart still pumps. What must the heart cells be able to do? 44) ______ A)continue aerobic metabolism when skeletal muscle cannot B)remove oxygen from lactate C)remove lactate from the blood D)transform lactate to pyruvate again E)derive sufficient energy from fermentation 45)Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements describes a function of phosphofructokinase? 45) ___C___ A)It catalyzes the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate, an early step of glycolysis. B)It is activated by AMP (derived from ADP). C)It is an allosteric enzyme. D)It is activated by ATP. E)It is inhibited by citrate, an intermediate of the citric acid cycle. 46)Which of the following statements describes NAD+? 46) __B____ A)NAD+ has more chemical energy than NADH. B)NAD+ is reduced to NADH during both glycolysis and the citric acid cycle. C)NAD+ can donate electrons for use in oxidative phosphorylation. D)NAD+ is reduced by the action of hydrogenases. E)In the absence of NAD+, glycolysis can still function.