BIOL 3333 PRACTICE EXAM 1 Questions With 100% Verified Answers A+ Score

The centromere of a chromosome is located nearer one end than the other, so there is a short chromosome arm and a long arm. This type of chromosome structure would formally be described as - correct answers Acrocentric A female of the genotype BBRrNngg is mated to a male of the genotype. BbRrNNgg. How many genetically different kinds of offspring can they produce? - correct answers 12 = 2 X 3 X 2 X 1 Plum (Pm) is a dominant mutation flies that causes the eyes to be dark purple. Homozygous Plum flies do not survive past their early larval development. What percentage of the progeny from a cross between two Plum-eyed flies would you expect to have normal eye color? - correct answers 1/3 A newly-discovered kind of field mouse in South America is found to have 22 pairs of chromosomes? How many bivalents are formed during the first meiotic division? - correct answers 22- the number of bivalents is the same as the haploid number In a trihybrid cross, how many genetically different types of offspring will be produced? - correct answers 27 = 3 X 3 X 3 A human cell at prophase II of meiosis will normally have how many centromeres? - correct answers 23 - the reduction division occurred in the first meiotic division Two short-haired poodles are mated, and they produce 9 long-haired and 25 short-haired baby poodles. Which allele is dominant? - correct answers Short hair - this is statistically close to a 1:3 = 3: 1 ratio If the mother's haplotype for four linked genes that show multiple allelism is: A 4, A 7, B 8, B 2 ,C 4, C4, D 9, D 1 and her child is: A 7, A 9, B 8, B 5, C 4, C 3, D 9, D 9, which of following could no be the biological father? - correct answers A 4, A 5, B1, B5, C 9, C 6, C 9, D 9, D 3 could not be the father because he has no A 9 or C 3 In a genetic cross you are analyzing, you find a situation in which a dihybrid cross yields a 9:3:4 phenotypic ratio. This is an example of what phenomenon? - correct answers Recessive epistasis What stage of cell division is pictured here? - Chromosomes lined down the middle - correct answers Metaphase II. Note that the number of chromosomes is odd, not even What is the diploid chromosome number of the cell pictured in question #10? - correct answers 6 Phenylketonuria is a serious metabolic defect occurring in individuals homozygous for a recessive allele. If two normal parents have an affected son and a phenotypically normal daughter, what is the probability that the third child will be normal but be heterozygous for the phenylketonuria allele? - correct answers 1/2 - Both parents must be heterozygous, so child has 1/2 chance of being Pp. During which sub-stage of Prophase I does chromosome coiling first become visible as the chromomeres? - correct answers Leptotene DNA replication and repair must be complete before the cell is able to pass which checkpoint? - correct answers G2 - M In goldfish, a dominant mutation (F) causes the fins to be lengthened significantly. But this rare condition is variable in expression and has only 80 % penetrance. Among the 40 offspring of a cross between homozygous normal (f f) and heterozygous long fin (F f) fish, how many would you expect to have long fins? - correct answers 16 - Ff x ff = 1/2 ff = 0.8 penetrance = 0.4 probability / 40 fish x 0.4 = 16 fish This division of the cytoplasm during telophase is called - correct answers cytokinesis A man of blood group A marries a woman of blood group B and they have a child of blood group O. What is the genotype of the father ( denotes as alleles of the "I" gene, as we did in class)? - correct answers I A i During which sub-stage of Prophase I does pairing of homologous chromosomes occurs, although homologues are not yet tightly synapsed? During this substage the chromosomes continue to coil and shorten? - correct answers zygotene Consider the cross R R B b c c X r r B B C c. What proportion of all offspring will phenotypically resemble the first parent? - correct answers 1/2 resemble the first parent A married couple has children with blood types A and AB. The mother has blood type B. The father could have any of the following blood types except? - correct answers O blood type If the mother's haplotype for four closely-linked genes that show multiple allelism is?A 1 A 5 B 2 B 3 C 1 C 2 D 12 D 9, and her child is A 5, A 12, B 8, B 2, C 2, C 9, D 7, D 9, which of the following could be the biological father? - correct answers A 1 A 12 B 2 B 8 C 4 C 9 D 7 D 9 The fruit fly Drosophila melanogaster has four pairs of chromosomes, whereas another species of fly has three pairs of chromosomes. Assuming segregation but no genetic recombination (crossing over), in which species would you expect to see more genetic variation among the progeny of a cross? - correct answers Drosophila Consider human families with four children and assume that each birth is equally likely to result in a boy (B) or a girl (G)? What fraction will have the gender order G-G-G-B? - correct answers 1/16 will have that gender order In the offspring of a dihybrid cross, what proportion are expected to homozygotes? - correct answers 1/4 will be homozygotes Consider human families with four children and assume that each birth is equally likely to result in a boy (B) or a girl (G). What proportion will have exactly one girl? - correct answers 4/16 = 1/4 will have exactly one girl True/False One exception to the Mendelian "rule" of dominance and recessiveness is epistasis - correct answers False - epistasis involves two different genes. Mendel's rule is for alleles of one gene. In a self-fertilizing plant, what proportion of a trihybrid F2 will " breed true", that is, they will not segregate for any of the three loci? - correct answers 1/8 are completely homozygous Assume that a researcher is repeating the experiments that Mendel did pea plants. But his species had six linkage groups. If there is one heterozygous gene in each linkage group, how many genetically different kinds of pollen could be produced? - correct answers 64 genetically different kinds of pollen Assume that Achondroplasia is a dominant mutation that causes a reduction in limb growth. Homozygotes do not survive past their early stages of development. What percentage of the progeny from a cross between two individuals with the Achondroplasia condition would you expect to be phenotypically normal? - correct answers 1/3 will be phenotypically normal In a pedigree, what does a diamond symbol represent? - correct answers a child whose gender is unknown Assume that a recessive trait (g g) has a penetrance of 0.6. In a cross of two heterzygous (G g) individuals, what is the expected ratio of normal to affected offspring? - correct answers 85:15 A phenotypic ratio for monohybrid cross of a gene showing co-dominance - correct answers 1:2:1 Phenotypic ratio for dominant epistasis - correct answers 12:3:1 Genotypic ratio for dihybrid testcross - correct answers 1:1:1:1 What stages of cell division is represented in the diagram at the right, if 2n=12? - correct answers prophase II of meiosis A researcher studying the chromosomes of snails from Panama finds one with 18 chromosomes. How many bivalents are formed during the first meiotic division in this species? - correct answers 9 bivalents A rare dominant trait, expressed only in men, is genetically transmitted to half their sons and to half their daughters. The gene for this trait is carried on what kind of chromosome - X chromosome, Y chromosome, or autosome? - correct answers Autosome