BIOL 1403             TEST #4                                    ______________________________
FALL 1998            100 points                                                                 NAME
DR. DINI                 FULL ESSAY VERSION

Answer both essay questions in Group A, one essay question each from Groups B and C, plus any other essay question from Groups B or C, for a total of 5 essays (20 points each). Using ink, answer questions neatly, logically, completely, concisely and in well-organized paragraph format.

Return this sheet along with your essays. Bust a move!

Group A

1. Construct an argument, using the structural/functional features of chloroplasts and mitochondria, that supports the endosymbiotic theory for their origin.

2. Beginning in the early 1950s, just a few years after antibiotics came into common use, many species and strains of bacteria (especially those that live in hospitals and clinics) were found to be resistant to those same antibiotics. Today, the problem has reached crisis proportions. Use the phenomenon of antibiotic resistance to contrast Lamarck’s mechanism of evolution with Darwin’s mechanism of evolution.

Group B

 3. Explain the biological basis for the contraceptive or abortifacient activity of: (a) the mini-pill, (b) the combo pill, (c) RU-486, (d) an IUD without copper or progestin, and (e) nonoxynol-9.

4. Describe the abnormal results that one should expect to achieve in an amphibian embryo by: (a) transplanting a portion of the dorsal lip to another region on the surface of the embryo, (b) transplanting a portion of the notochord to another region of the embryo, directly underneath ectoderm, and (c) transplanting a portion of the optic cup to another region of the embryo, directly underneath ectoderm. What phenomenon is chiefly responsible for these results?

Group C

5. Explain how it is that the current Darwinian revolution can be said to be repeating history.

6. Describe four vestiges or atavisms found in humans as well as their previous functions. Separately, use natural selection to explain the development of the current condition of each structure.

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BIOL 1403                                         Test #4                                 __________________________
FALL 2000                                         Full-Essay Version                                   NAME
DR. DINI                                             100 points

Using ink and writing in paragraph format, answer essay questions 1 through 4 (20 points each). Then answer genetics problems 5 through 9 in the spaces provided, being sure to show your work and to clearly indicate your final answer (4 points each). Essays must be legible, complete, concise, logical and well organized to receive full credit. You may write on both sides of your paper. Please return these sheets along with your essays. Dominate!!!

1. Describe the physical evidence, from their anatomy and physiology, that supports the endosymbiotic origin of mitochondria and chloroplasts.

2. Describe three vestigial organs/structures found in adult humans, being sure to include the original function(s) of each. Then, choose one of these and explain how Lamarck would have accounted for its becoming vestigial and contrast that with how Darwin would have accounted for its becoming vestigial.

3. Use the human disorders cystic fibrosis (CF) and sickle cell anemia to demonstrate the inadequacy of the concept of dominance.

4. What features of human embryos indicate our common ancestry with aquatic vertebrates? The genes that produce these features are transcribed only during a certain part of embryonic development, but are not transcribed ever again. What is the probable means by which these genes become permanently inactivated?

Genetics Problems

5. Color pattern in a species of duck is determined by one gene with three alleles. Alleles H and I are codominant, and allele i is recessive to both. How many phenotypes are possible in a flock of ducks that contains all the possible combinations of these three alleles?

6. In tigers, a recessive allele causes the absence of fur pigmentation (a "white tiger") and a cross-eyed condition. If two phenotypically normal tigers that are heterozygous at this locus are mated, what percentage of their offspring should be cross-eyed? What percentage should be white?

7. A man of unknown genotype for the ABO blood group has a sister who has Type B blood, a father with Type B blood, a mother with Type O blood, and he marries a woman with Type AB blood by whom he has two daughters with Type A blood. What is/are his possible genotypes?

8. When just one copy of a certain allele (A) is present, it causes a severe disorder, but does so only if a second gene exists in the homozygous recessive (bb) condition. A man who is heterozygous for both genes marries a woman who is homozygous recessive for the first gene and heterozygous for the second gene. What are the chances of the disorder appearing among their children?

9. Hemophilia A is an X-linked recessive trait. A woman without hemophilia had a hemophiliac father. There was no evidence of hemophilia on either side of her mother’s family going back many generations. If she marries a male hemophiliac, then what are the chances that their offspring will have the same genotype as their maternal grandmother (i.e. the woman’s mother)? Considering both gender and blood clotting ability together, provide your answer as a single percentage.

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BIOL 1403                             Test #4                                  __________________________  
FALL 2001                            Full-Essay Version                                   NAME  
DR. DINI                                100 points  
 

Using ink and writing in paragraph format, answer all four essays (20 points each).  Answers must be legible, complete, concise, logical and well-organized to receive full credit.  You can write on both sides of your paper.  Then, also using ink, answer the four genetics problems by circling the correct responses AND, whenever a question asks you to choose a fraction or percentage, SHOW YOUR WORK in the box provided (5 points each).  Please return all of these sheets along with your essays.

Essays

1. In accord with the endosymbiotic theory, make predictions about what one should expect to observe regarding (a) the process whereby mitochondria and chloroplasts reproduce themselves, (b) the kind of transcription unit found in mitochondria and chloroplasts, and (c) the proteins needed to carry out transcription in mitochondria and chloroplasts.  
 

2. How is the “Evolution Revolution,” which has been going on since Darwin published “On the Origin of Species” in 1859, similar to the “Copernican Revolution” of the 1600s?  
 

3. Describe what you think is the strongest evidence of evolution that has been covered so far in this course, being sure to explain WHY you think it is the strongest evidence.  
 

4. What is a Barr body, and how does it relate to the control of gene expression?

 

Genetics Problems

 

1. Two, diploid insects with purple-colored exoskeletons breed with each other and produce 612 purple offspring, 302 red offspring and 293 blue offspring.   
 

(A) What is the SIMPLEST explanation for these results?  
(i) complete dominance                      (iv) pleiotropy  
(ii) codominance                                 (v) epistasis  
(iii) incomplete dominance

 

(B) What should be true of the parents?  
(i) Each parent produces two different gene products, in roughly equal amounts.  
(ii) They are homozygotes.  
(iii) Their phenotype is the result of having 1/2 as much gene product, yet this is enough to make them identical in appearance to homozygous insects.  
(iv) Each parent produces but a single gene product, and only 1/2 as much as seen in homozygotes.

 

 

 

(C) If a red insect breeds with a blue insect, then  
what percentage of the offspring should be red?  
(i) 0%               (ii) 25%            (iii) 50%           (iv) 75%           (v) 100%

 

(D) If a red insect breeds with a purple insect, then  
what percentage of their offspring should be red?  
(i) 0%               (ii) 25%            (iii) 50%           (iv) 75%           (v) 100%

 

 

 

(E) In the simplest possible scenario, how many copies of the gene for exoskeleton color (i.e. how many gene loci) should each purple insect’s somatic nuclei contain, and how many different alleles?  
(i) 1,2               (ii) 1,1              (iii) 2,1             (iv) 2,2             (v) 2,3

 

2. One human parent has Type A blood, the other has Type B blood.  They have a child with Type O blood.  
 

(A) From the description above, what must be true of these parents?  
(i) Both parents are Rh-positive.  
(ii) Neither of them has antigens of the ABO blood group on their red blood corpuscles.  
(iii) Each parent has all three alleles of the ABO blood group in his/her genome.  
(iv) Both are heterozygous for their particular ABO blood type.

 

 

 

(B) What percentage of their offspring should have  
Type O blood?  
(i) 0%               (ii) 25%            (iii) 50%           (iv) 75%           (v) 100%

 

(C) If a Type O individual marries a Type AB individual, then their children may be:  
                                                            1. Type A
                                                            2. Type B
                                                            3. Type AB  
                                                            4. Type O  
 (i) 1 only         (ii) 3 only          (iii) 3 & 4          (iv) 1 & 2          (v) all of these  
 

(D) When the phenotype under study is blood type, the phenotype of individuals with Type AB blood is due to which inheritance pattern?  
(i) complete dominance                      (iv) pleiotropy  
(ii) epistasis                                         (v) codominance   
(iii) incomplete dominance  
 

(E) Which term most accurately describes the inheritance pattern observed in Type A or Type B persons who are heterozygous?  
(i) complete dominance                      (iv) pleiotropy  
(ii) codominance                                 (v) epistasis  
(iii) incomplete dominance

 

3. Assume that in humans, the pigmented condition is completely dominant to the albino condition, and brown eyes are completely dominant to blue eyes.  A blue-eyed woman whose mother was albino, marries an albino man whose mother’s ancestors had all been brown-eyed and whose father’s ancestors had all been blue-eyed.  
 

(A) Considering these two traits together, how many different types of sex cell can each of these parents make?  
(i) 1                  (ii) 2                 (iii) 3                (iv) 4                (v) 6  
 

(B) What percentage of their offspring should have blue eyes?  
(i) 0%               (ii) 25%            (iii) 50%           (iv) 75%           (v) 100%

 

 

 

 

 

 

(C) What percentage of their offspring should have red eyes?  
(i) 0%               (ii) 25%            (iii) 50%           (iv) 75%           (v) 100%

 

(D) If an incestuous relationship occurs between two pigmented offspring of this marriage, and if these two incestuous individuals have different eye colors from each other, then what fraction of their offspring should be blue-eyed?  
(i) 1/8               (ii) 1/4              (iii) 3/8             (iv) 1/2             (v) 5/8

 

 

 

 

 

 

 

 

 

   

(E) What genetic phenomenon is exhibited by the two traits in relation to each other?  
(i) X-linkage                 (ii) pleiotropy                (iii) codominance            (iv) epistasis

4. An X-linked, recessive disorder of humans called Anhidrotic Ectodermal Dysplasia (AED) is characterized by lack of sweat glands and lack of teeth.  A normal male has children by a normal woman whose father was born without teeth and sweat glands.  
 

(A) From the description above, what is true of the gene that causes AED?  
(i) It has multiple alleles.                                             (iv) Males inherit it from their mothers.  
(ii) It exhibits pleiotropy.                                               (v) Both (ii) and (iv) are correct.  
(iii) It can be homozygous in wild-type males.  
 

(B) To whom will affected males pass on the gene for this disorder?  
(i) all of their daughters                       (iv) 1/2 of their sons  
(ii) 1/2 of their daughters                     (v) all of their offspring  
(iii) all of their sons  
 

(C) What fraction of the female offspring of this marriage should be carriers of this disorder?  
(i) 1/8               (ii) 1/4              (iii) 1/3             (iv) 1/2             (v) 3/4  
 

(D) What fraction of the offspring of this marriage should completely lack sweat glands and teeth?  
(i) 1/16             (ii) 1/8              (iii) 3/16                       (iv) 1/4             (v) 1/2  
 

(E) What fraction of the offspring of this marriage could have patches of skin with sweat glands interspersed among patches of skin that lack sweat glands?  
(i) 1/16             (ii) 1/8              (iii) 3/16                       (iv) 1/4             (v) 1/2

 

 

 

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BIOL 1403                             Test #4                                  __________________________
FALL 2002                            All-Essay Version                                       NAME
DR. DINI                                100 points

 Using ink and writing in paragraph format, answer all four essays.  Answers must be legible, complete, concise, logical and well organized to receive full credit (20 points each).  You can write on both sides of your paper.  Then, in the spaces provided, answer the four genetics problems, being sure to SHOW YOUR WORK and to circle the answers (5 points each).  Excel!

1. Use the rise of antibiotic resistance among bacteria to contrast Lamarck’s mechanism of evolution with Charles Darwin’s mechanism of evolution.

2. How do scientific and non-scientific definitions of the word “theory” differ from each other?  How does this difference contribute to the long-standing controversy outside of scientific circles concerning the theory of evolution?

3. What is true of gene expression on the inactivated X chromosomes in somatic cells of female mammals, and how is this level of expression achieved?  What are the possible phenotypic consequences of X inactivation in female mammals?  Provide an actual example.

4. Some biologists propose that the endosymbiotic theory should be extended to include the origin of cilia and flagella.  They propose that a relationship, such as that between Mixotricha paradoxa and its surface spirochetes, evolved into a cell:organelle relationship.  Describe three predictions that one might make about the structure/biochemistry of modern cilia that are in accord with this proposal.

Genetics Problems

1. In a hypothetical situation, the pigmented condition (melanin in hair, skin, and iris) is haplo-sufficient, and albinism results from having two copies of a mutated allele.  At a second gene affecting eye color, the brown-eyed condition is haplo-sufficient, whereas the blue-eyed condition results from having two copies of a mutated allele.  If two parents are heterozygous for both genes and have many offspring, then what are the possible phenotypes of their offspring, in what ratio should these phenotypes exist, and what phenomenon explains the divergence from a 9:3:3:1 ratio?

 

2. In horses, coat color may be palomino (PP), cremello (Pp), or tan (pp).  Which of the following crosses should produce offspring, 50% of which are cremello?

a) palomino x cremello

b) tan x cremello

c) cremello x cremello

 

3. Aside from the ABO blood group, there exists another RBC glycoprotein called the Rhesus factor.  Those who have this factor are described as Rh+, whereas those who lack it are described as Rh-.  The Rh+ allele is haplo-sufficient.  A man with A-positive blood marries a woman with B-positive blood, and they have children together. These parents are heterozygous for both of these traits.  In the same fashion as given in the fourth sentence of this problem, list all of the possible phenotypes of their offspring, and their probable ratios.

 

4. A man and a woman, both of normal color vision have (1) a red/green colorblind son who has a daughter of normal vision, (2) a daughter of normal vision who has one colorblind and one normal son, and (3) another daughter of normal vision who has five sons, all normal.  Present the probable genotypes of all of these individuals in the form of a pedigree.

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BIOL 1403                             Test #4                                __________________________
FALL 2003                            All-Essay Version                                       NAME
DR. DINI                                100 points

Using ink and writing in paragraph format, answer the four essay questions.  Answers must be legible, complete, concise, logical, and well organized to receive full credit (20 points each).  You can write on both sides of your paper.  Then, still using ink, answer the four genetics problems on the sheets provided, circling your answers, and being sure to SHOW YOUR WORK in the spaces provided in order to receive full credit (5 points each).  Please return this sheet along with your completed essays.  Prevail!!!

Essay Question

 

  1. In an electron microscopy course, a student discovers a kind of eukaryotic organelle that has 3 distinct phospholipid bilayers (i.e. it is triple-membraned).  What is the likeliest explanation for the origin of this kind of organelle?  Discuss three predictions about three different parts of this organelle’s structure that it would be logical to make, based on this explanation.

 

  1. Choose a single human vestigial organ, describe its current structure and compare this to its ancestral structure and function.  Next, discuss how Lamarck would have explained how the organ became vestigial.  Finally, discuss how Darwin would have explained how it became vestigial.

 

  1. What are the phenotypic consequences of X inactivation in mammals?  What is the connection between X inactivation and eukaryotic control of gene expression?

 

  1. What were the long-term consequences of Galileo’s conviction as a heretic, and how could these consequences have been avoided?

Genetics Problems

 5. A Type AB man marries a Type O woman.  (A) What should be the blood types of their immediate offspring (the F1 generation), and in what ratio?  If there is incest among two of these F1 offspring, and if these two offspring have different genotypes, then (B) what should be the blood types of the grandchildren (the F2 generation), and in what ratio?

A gene has a wild-type allele that causes growth of hair between the joints on the dorsal surfaces of the fingers (mid-digital hair).  A mutated allele produces no gene product; the phenotype of heterozygotes is indistinguishable from the wild-type phenotype.  At another locus on the same chromosome is a gene that affects finger length.  At this second locus, possessing a single copy of a mutated allele is enough to cause fingers to be short (lacking the area between the two joints), whereas possessing two copies of the mutated allele results in the absence of fingers.  In the nuclei of a man’s somatic cells, one homolog bears the allele that causes NO mid-digital hair, and the allele that causes short fingers.  The other homolog carries, instead, both of the wild-type alleles. 

6. He marries a woman whose fingers are of wild-type length, but which lack mid-digital hair.  What proportion of their offspring should have the same phenotype as their mother?

 

There are about 20 varieties of a skin disorder called ichthyosis, wherein the skin develops fish-like scales.  About 95% of cases are caused by an autosomal dominant disorder (ichthyosis vulgaris, frequency ≈ 1:300).  The very few X-linked ichthyosis cases are, instead, caused by a recessive allele.  The symptoms in both varieties are fairly similar.  Dead skin cells build up and form scales from 1 mm to 1 cm in diameter.

7. A man and a woman, who do not have the vulgaris variety, also have no incidence of ichthyosis vulgaris among any of their ancestors.  The woman, who has ichthyosis scales ONLY on her left shin, marries the man, who completely lacks ichthyosis.  What proportion of their sons should express ichthyosis, and what variety of ichthyosis should it be?

 

8. In a hypothetical bird species (not the same one discussed in class), two different genes affect feather color.  One gene has a wild-type allele that deposits yellow pigment in feathers, whereas a highly mutated allele produces no pigment.  A second gene has a wild-type allele that deposits blue pigment in feathers; it, too, has a highly mutated allele that produces no pigment.  Feathers lacking pigments are white.   Individually, both of the wild-type alleles are haplosufficient.

A male and female bird of this species are both heterozygous at the two gene loci, and both have only green feathers.  What are the possible phenotypes of their offspring, and in what ratio?

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BIOL 1403                              Test #4                                   ___________________________
FALL 2004                              ALL-ESSAY VERSION                                 NAME
DR. DINI                                 100 points

Using ink and writing in paragraph format, answer the four essay questions below neatly, logically, completely, concisely, and in a well-organized fashion (20 points each).  Then, still using ink, answer the four genetics problems on these sheets in the spaces provided, being sure to SHOW YOUR WORK and circle your answers in order to receive full credit (5 points each).  Please hand-in this sheet with your other papers.

1. Distinguish between the scientific terms “hypothesis” and “theory,” citing actual examples of each.  Explain what is incorrect about the phrase “evolution is just a theory.”

 

2. For many traits, phenotype results from an interaction of genotype and environment.  For either a prokaryote OR a eukaryote, explain how a chemical signal from the environment can affect phenotype.  (HINT: in prokaryotes, phenotype is determined by whether…..)

 

3. Which processes are the major sources of genetic variation (i.e. of new alleles) in eukaryotes?  Explain the probable consequences for eukaryotes if these processes were, somehow, interrupted while the environment continued to change continuously.

 

4. Can the genomes of mitochondria and chloroplasts be considered vestigial?  Why or why not?  To what are these genomes homologous, and what is the evidence for this?

Genetics Problems

 

5. An albino man has children with a woman who has no history of albinism on either side of her family.  If incest occurs among two of their offspring, what fraction of the F2 should be albino?

6. Two gray-feathered birds breed, producing many offspring.  Among the offspring, 36 have white feathers, 40 have black feathers, and 76 have gray feathers.  Assuming that an autosomal gene controls feather color in this hypothetical bird species, describe how two simple inheritance patterns can separately account for these observations.

7. A Type A woman has children by a Type B man whose mother had Type O blood.  The man and woman can both clot their blood, though the woman’s father was a hemophiliac who had Type O blood.  What fraction of their children should have the same phenotype (sex, blood type, clotting ability) as their father?

8. In a hypothetical species of monkey, an X-linked gene controls facial skin color.  There are three alleles in the gene pool: F1 produces red pigment, F2 produces blue pigment, and f produces no pigment (albino).  An albino male mates with a female that has both red and blue skin on her face.  Give all of the possible phenotypes among their offspring (sex, facial coloration), and the simplest ratio in which these phenotypes should occur.

BIOL 1403                              Test #4                                   ___________________________
FALL 2005                              ALL-ESSAY VERSION                                  NAME
DR. DINI                                 100 points

Using indelible ink and writing in paragraph format, answer the four essay questions below neatly, logically, completely, concisely, and in a well-organized fashion (20 points each).  Then, still using ink, answer the four genetics problems on these sheets in the spaces provided, being sure to SHOW YOUR WORK and circle your answers in order to receive full credit (5 points each).  Please hand-in these sheets with your other papers.

1. How do the structural features of mitochondria and chloroplasts support the theory of evolution?

2. What affect does the existence of Barr bodies have on regulation of the expression of heterozygous, sex-linked genes in female mammals?

3. Though Darwin was unaware of them, mutation and crossing-over play important roles in evolution by natural selection.  Discuss their general role in natural selection, and the relationship of this role to differential reproduction.

4. How can the arrector pili that are associated with body hair follicles be described as “vestigial,” despite the fact that they can still contract?

Genetics Problems

 5. In humans, brachydactyly (short fingers) occurs when one inherits a single, “dominant” allele; inheritance of two such alleles causes complete absence of fingers (complete absence of fingers is not called “brachydactyly”).  Lacking these mutated alleles, one has wild-type fingers.  At a different gene, inheriting a single “dominant” allele causes polydactyly (>5 fingers on each hand); inheriting two such mutated alleles is lethal in utero.  A man with brachydactylous, 5-fingered hands has children with a woman who is both brachydactylous and polydactylous. 

(a) What percentage of their offspring should have 5 wild-type fingers on each hand?

(b) What percentage of their offspring should be both brachydactylous and polydactylous?

 

6. A normal-sighted woman whose father had red-green colorblindness, has children by a wild-type man. 

(a) What percentage of their offspring may exhibit red-green colorblindness in only part of their visual field, and (b) what accounts for this partial colorblindness?

 

7. A man with Type A blood has children with a woman who has Type B blood; they have a Type O offspring, and subsequently have more children together. 

(a) What percentage of their offspring should have a blood type that is the result of codominance?

(b) What percentage of their offspring should have a blood type that is the result of haplo-sufficiency?

 

8. As discussed in lecture, human achondroplasia (a type of dwarfism) is inherited as an autosomal dominant, whereas albinism is inherited as an autosomal recessive.  Inheriting two of the achondroplasia alleles results in spontaneous abortion (i.e. lethality in utero).  A wild-type male whose father was albino, marries a pigmented dwarf whose mother was albino.

(a) What percentage of their offspring should be albino dwarves?

(b) What percentage of their offspring should have the wild-type phenotype for both traits?

 

BIOL 1403                              Test #4                                   ___________________________
FALL 2006                              ALL-ESSAY VERSION                                  NAME
DR. DINI                                 100 points

Using indelible ink, answer the four genetics questions on the pages provided, being sure to SHOW YOUR WORK, and to CIRCLE THE ANSWERS (5 points each).  Then, on paper you provide, answer the four essay questions correctly, neatly, logically, completely, concisely, and in a well-organized fashion (20 points each).  Please hand in this sheet with your other papers.  Allez!  Allez!  Allez!

Genetics Problems

 1. Barth Syndrome is a rare, X-linked recessive disorder caused by a mutation.  The mutated allele produces an abnormal enzyme which, in turn, produces an altered version of a mitochondrial phospholipid which can cause heart failure, diminished WBC counts, and short stature, among other symptoms.

Sam has Barth Syndrome, and neither of his parents do (though he inherited the mutated gene from one of them).  If Sam marries a woman with the same genotype as his mother, what are the chances that they will have daughters with Barth Syndrome?

 

2. An autosomal dominant disorder, Marfan Syndrome is caused by a mutation of the fibrillin-1 (FBR1) gene.  The more-common symptoms are long limbs and digits, breastbone deformities, mitral valve leakage, and a high risk of aortic aneurysms.  Those homozygous for mutated versions of FBR1 are never born.

Unknown to them, Harry and Sally both have Marfan Syndrome.  What proportion of their liveborn children should have the wild-type phenotype?

 

3. One of at least a dozen human blood groups is the Xg blood group.  There are two alleles: Xg(a+) produces the Xg glycoprotein on RBCs, whereas Xg(a-) is a mutated allele that produces no gene product.  The gene is X-linked.

Trevor has Xg+ blood and his wife, Tina, has Xg- blood.  (a) What are the chances that they will have a child with two populations of RBCs in circulation; half of them Xg+ cells, and the other half Xg- cells?  (b) How would you account for the observation that, instead, 20% of the RBCs in such a child are Xg+, whereas the other 80% are Xg-?

 

4. In a hypothetical situation, the wild-type allele of a gene causes eyebrow hair to be present, whereas a recessive allele causes its absence.  A separate gene, which affects coarseness of eyebrow hair, also has two alleles in the gene pool.  The wild-type allele, which is haplo-insufficient, produces coarse hair, whereas the mutated allele produces fine hair.

A woman whose eyebrows have coarse hair (though her mother had NO eyebrow hair) has children by a man who is heterozygous for both genes.  (a) What proportion of their children should have the same phenotype as their mother?  (b) What proportion of their children should have the same phenotype as their father?

Essay Questions

1. Discuss the relationship of Barr bodies to gene expression in female mammals.  A portion of your essay should include how Barr bodies come about, as well as their genetic significance.

2. What were the immediate ramifications of Galileo’s trial and house arrest?

3. What are two major differences between natural selection and inheritance of acquired traits in terms of how they explain evolution?

4. What is the relationship between homologous structures and vestigial structures?   Explain how the theory of evolution accounts for the existence of each, and give actual examples of each.

 

BIOL 1403                              Test #4                                   ___________________________
FALL 2007                              ALL-ESSAY VERSION                               NAME
DR. DINI                                 100 points

Using indelible ink, answer the four genetics questions on the pages provided, being sure to SHOW YOUR WORK, and to CIRCLE THE ANSWERS (5 points each).  Then, on paper you provide, answer the four essay questions correctly, neatly, logically, completely, concisely, and in a well-organized fashion (20 points each).  Please hand in this sheet with your other papers.  Spank this bad puppy!

Genetics problems

1. In humans, a phenotype known as “spotted teeth” is caused by a completely dominant (haplo-sufficient), sex-linked allele.  A man with spotted teeth whose mother had wild-type teeth marries a woman with wild-type teeth.  (a) Based on the information above, is the gene X-linked or Y-linked?  (b) What should be true of the couple’s daughters regarding this phenotype? (c) Of the couple’s sons?

2. In a certain species of bird is an autosomal gene that controls feather color.  There are two different alleles of this gene in the species’ gene pool.  Three phenotypes are observed in this species: gray-feathered birds, black-feathered birds, and splashed-white-feathered birds.  Crosses among these three phenotypes yield the following results:

 

Parents                                              Offspring

black x gray                                         black and gray (1:1)

black x splashed-white                       gray (all)

gray x splashed-white                         gray and splashed-white (1:1)

black x black                                       black (all)

splashed white x splashed-white        splashed-white (all)

(a) What offspring phenotypes, and in what ratio, should one expect from a cross of gray x gray?  (b) What are the two simplest, inheritance patterns that can account for these results, and (c) how does each inheritance pattern produce gray feathers?

3. The following situation involves two autosomal genes in cats.  The genotype AA produces tabby fur color; Aa is also tabby; aa is black. The second gene (on a different chromosome) is epistatic to the gene for tabby/black fur color.  Allele W is haplo-sufficient and produces white fur.  Cats with the ww genotype develop colored fur, as per the first gene.  If two parental cats are heterozygous for both genes, what fur colors, and in what ratio, should be expected among the F1 offspring?

4. The following pedigree shows the pattern of inheritance of red-green color blindness in a human family.  Females are shown as circles, males as squares.  Shaded symbols indicate color-blind individuals; open symbols indicate wild-type individuals.

 Sorry.  Pedigree unavailable in this format.  See tests cat back of lab manual.

(a) Apart from the P1 female, what should be true of the genotypes of all other females depicted on this pedigree?  (b) What is the chance that a son of the female indicated by the arrow will be colorblind if the father has wild-type vision? (c) If the father is color-blind?  (ignore X-inactivation).

Essay Questions

You fixed the earth on its foundation, never to be moved.
                                                                              Psalm 104:5

5. How did the passage above (and similar passages from the Judaeo-Christian scriptures) figure in the Copernican Revolution?  What lesson derived from the current standard interpretation of the same passage might have prevented religious conflict concerning the theory of evolution?

6. Explain how an inducible operon is turned on (activated), and how it is subsequently turned off (inactivated) again.  In what type of cell does this occur, and what benefit comes to these cells by being able to turn on/off operons?

7. Describe two human vestigial organs that are the result of a dietary shift from herbivory to carnivory in our ancestors.  Chose one of these vestigial organs and explain how natural selection can account for its becoming vestigial.

8. Distinguish between complete, incomplete, and codominance, giving an actual example of each.

 

BIOL 1403                             Test #4                                  __________________________
FALL 2008                            All Essay Version                                    NAME
DR. DINI                                100 points

Using ink and writing in paragraph format, answer the four essay questions below correctly, neatly, logically, completely, concisely, and in a well-organized fashion (20 points).  Then, still using ink, answer the four genetics problems, placing answers in squares where provided, and being sure to construct Punnett squares in the blank areas in order to receive full credit (5 points each).

Essay Questions

1. In west Texas, cotton grows at the edge of its moisture range.  If global warming causes the west Texas climate to become drier than it currently is, cotton may not be profitably grown here UNLESS a new drought-resistant strain occurs.  Without including human activity, discuss how Darwin would explain the evolution of a cotton strain that is adapted to dry conditions.

2. Consider the following exonic nucleotide sequence from the template (transcribed) strand of a DNA molecule.

                        Template DNA:           3’ --- A C A T C A G G T G T A A C G --- 5’ 

A) Using the dictionary of the genetic code as needed, and always working from left to right, perform the necessary steps to determine the corresponding amino acid sequence.

B) Say the guanine (G) that is located at the 5’ end of the DNA sequence above is mutated such that it is replaced by a Thymine (T).  This mutation can be described by which three terms from the classification of different types of mutations, given what the new codon codes for, and without making any assumptions?  Provide a brief rationale for each choice.  

C) If this template DNA sequence is located at the upstream end of the most upstream exon in a protein-coding gene, then what is most likely to be true of the gene product of this gene as a result of this mutation?

D) Given the nature of the gene product from this mutated gene, which of these inheritance patterns: complete dominance, incomplete dominance, and/or codominance, are possible to appear in heterozygotes with one copy of the original gene, and one copy of this mutated gene?  Explain your choice(s).

3. Someone claims: “There is no physical evidence that eukaryotic cells evolved from prokaryotic cells!”   How would a knowledgeable biologist respond?

4. How are inducible operons induced?  How are they repressed again once their gene products are no longer needed?

Genetics Problems

5. A man and woman have numerous children.  All four of the ABO blood types are represented among these children.

A) What are the genotypes and blood types of this man and woman?

 

B) Which specific offspring blood type(s) is/are due to complete dominance?

 

C) Which specific offspring blood type is due to non-Mendelian inheritance?

 

6. In a hypothetical situation, the haplo-sufficient allele Q permits arms and legs to develop, but allele q prevents limb development when homozygous.  Another gene, located on a different chromosome, causes achrondroplasia among heterozygotes, whereas fetuses homozygous for the achondroplasia allele are spontaneously aborted, and individuals homozygous for the wild-type allele have wild-type proportions (if they have limbs).  An achondroplastic dwarf whose father had no limbs marries an achondroplastic dwarf who is known to be a carrier of allele q

A) What fraction* of their conceptions are expected NOT to be born?

 

B) What fraction* of their live-born offspring should be limbless?

 

C) What fraction* of their live-born offspring should have the achondroplastic limb phenotype?

 

D) Fill in the blanks to correctly complete this sentence: As far as limb phenotype is concerned, the _________________ gene is epistatic to the ___________________ gene.

*A Report answers as simplified fractions

7. When a long-squash plant is crossed with a round-squash plant, none of the next generation’s offspring have long or round squash; rather, they all have oval squash.  A single gene controls squash shape, i.e. squash shape is not a polygenic trait.

A) What phenotypes should appear among the offspring of a cross between two oval-squash plants, and in what ratio?

 

B) Propose one (and only one) genetic explanation for these observations (the observations from question 7 and from the correct answer to part (A).  Be as specific as possible.

8. A man with the X-linked recessive disorder, AED, lacks teeth and sweat glands.  He marries a wild-type woman with no family history of AED.

A) What percentage of this couple’s daughters should carry the allele for AED?

 

B) If one such carrier daughter marries a man with AED, then what percentage of their offspring should potentially be mosaics for this trait?

 

C) If one such carrier daughter marries a man with AED, then what percentage of their offspring should be daughters without any teeth or sweat glands?

 

 

BIOL 1403                             Test #4                      __________________________
FALL 2009                            All Essay Version                        NAME
DR. DINI                                100 points

Using ink and writing in paragraph format, answer the four essay questions below correctly, neatly, logically, completely, concisely, and in a well-organized fashion (20 points each).  Then, still using ink, answer the four genetics problems, being sure to show your work and Punnett squares in order to receive full credit (5 points each).  Hand in this sheet along with your work.

Essay Questions

1. There is an antibiotic called methicillin.  Currently in hospitals and clinics, a type of bacterium called methicillin-resistant Staphylococcus aureus (MRSA) is growing in abundance, and causing widespread infection among patients.  In stepwise fashion, explain how natural selection accounts for the increased incidence of MRSA, relative to non-resistant S. aureus.

2. Compare Galileo and Darwin concerning (i) the impact their work had on humanity’s understanding of its position in nature, and (ii) why their work was not favorably received by most Christian churches of their times.

3. Basing your thoughts on endosymbiotic theory as regards the origin of mitochondria and chloroplasts, make predictions about the current conditions of these organelles concerning (i) the way genes on their circular chromosomes should be organized and regulated, and (ii) the number of different RNA pols that should catalyze transcription.

4. Describe three vestigial organs found among various animals (do NOT limit yourself to humans), including in your description the ancestral function of each and an explanation of how evolutionary theory accounts for the current condition of each.

Genetics Problems

5. A woman with Type A blood and a man with Type B blood have a child with Type O blood. 

A) What is the chance that this couple can have offspring with Type AB blood?
B) What is true of both parents’ genotypes, and for what percentage of their offspring should this also be true?
C) Can the term “carrier” be applied to the parents, considering their blood types?  Explain.

6. Albinism and brachydactyly are inherited as discussed in class.  A female who is heterozygous for both genes (which are located on different chromosomes) marries a wild-type male whose father was albino.

A) What phenotypic classes are possible from this marriage, and in what ratio?
B) How is the term “haplo-insufficient” applicable to the mother?
C) Can the term “carrier” be applied to the mother?  Explain.

7. In a hypothetical species, haplo-sufficient gene A suppresses eye formation, whereas its allele, a, permits eye formation.  On a different chromosome, haplo-sufficient gene, B, is responsible for pigment in the iris of the eye, whereas its allele, b, produces no pigment in the iris.  A cross is made between a male with genotype AAbb, and a female with genotype aaBB.

A) What should be the phenotypic class(es) of the F1, and in what percentage(s)?
B) If one of the F1 offspring is mated to its mother, then what percentage of the offspring of this second cross should have the same genotype as the mother?
C) If one of the F1 offspring is mated to its mother, then what percentage of the offspring of this second cross should have the same phenotype as the mother?
D) Which term best describes the relationship of these two genes?  Explain.

8. In humans, an X-linked recessive allele causes hemolytic anemia (lysis of RBCs) upon taking the anti-malarial drug, primaquine.  Red-green colorblindness is inherited as discussed in class.  A wild-type woman, Cynthia, had a colorblind mother with no alleles for hemolytic anemia, whereas Cynthia’s father was susceptible to hemolytic anemia, but was not colorblind.  She marries Tom, a colorblind man who is susceptible to hemolytic anemia.

A) What is the chance that, among Cynthia and Tom’s offspring, will be daughters who are homozygous for susceptibility to hemolytic anemia?
B) If one such daughter is also red-green colorblind, what is the simplest explanation for her colorblindness?