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The strands of the DNA double helix are held together by: a. ionic bonds b. covalent bonds c. hydrogen bonds d. both a & b e. none of the above During infection of E. coli cells by bacteriophage virus, called T 2 : a. proteins are the only virus component that enter the infected cell b. both proteins and nucleic acids enter the cell c. only protein from the infecting phage can also be detected in progency phage d. more than one infecting phage particle is required to produce infection e. only nucleic acid enter the cell from the virus During mitosis, sister chromatids separate and move to opposite poles during: a. metaphase b. prophase c. synopsis d. telophase e. anaphase DNA replication occurs: a. during G1 b. during the S phase of interphase c. only during mitosis d. only during meiosis e. during G2 When dividing cells are examined under a light microscope, chromosomes seem to disappear during: a. metaphase b. anaphase c. prophase d. telophase e. none of the above When dividing cells are examined under a light microscope, chromosomes first become visible during: a. telophase b. metaphase c. prophase d. anaphase e. G1 In sexually reproducing organisms, the diploid phase of the life cycle begins at: a. spore formation b. gamete formation c. fertilization of the egg d. meiosis e. mitosis
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The diagnosis of Down Syndrome can be made by examining the individual's: a. spores b. pollen c. nucleosomes d. kinetochores e. karyotype During meiosis, the sister chromatids separate and move to opposite poles during: a. anaphase I b. anaphase II c. meiosis I d. metaphase e. telophase II The exchange of genetic material between chromatids on homologous chromosomes occurs during: a. interphase b. mitosis & meiosis c. prophase II d. prophase I e. anaphase II The number of chromosomes is reduced to half during: a. anaphase of mitosis b. anaphase I of meiosis c. anaphase II or meiosis d. fertilization e. interphase Which is true of mitosis: a. The chromosome number in the resulting cells is halved b. DNA replication is completed in prophase c. Crossing over occurs during phrophase d. It consists of two nuclear divisions e. Two genetically identical nuclei are formed A person with Klinefelter Syndrome has 44 non-sex chromosomes and 3 sex chromosomes (XXY). The resulting aneupolidy is caused by _______ during meiosis: a. crossing over b. nondisjunction c. mutation d. an enzyme deficiency e. failure of DNA to replicate How does sexual reproduction include genetic variability? a. By the exchange of genetic information between male and female gametes during meiosis II. b. By non-random separation of the chromosome pairs c. Through crossing over, independent assortment, and random fertilization d. None of the above
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DNA replication occurs: a. only before mitosis b. only before meiosis c. during chromosome condensation d. during G2 e. before both mitosis and meiosis When a given trait is the result of multi-gene action (such as coat color in mice), one of the genes may mask the expression of one or all other genes. This phenomenon is termed: a. epistasis b. pleiotropy c. dominance d. incomplete dominance e. none of the above In Mendel's experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants? c. tall; intermediate height; short T TT Tt t Tt tt
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T t
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It has been found that at a certain locus of the human genome, 200 different alleles exist in the population. Each individual person has at most _____ alleles at that particular locus: a. 50 b. 200 c. 100 d. 2 Cleft chin is a sex-linked (on X chromosome) dominant trait. A man with a cleft chin marries a woman with a round chin. What percent of their female progency will show the cleft chin trait? e. 100 Xc Y x Xc Xc (all females get 1X from Dad all heterozygous and express cleft)
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A pea plant with red flowers is test-crossed with a white flowered homozygous recessive plant and one-half of the result progeny have red flowers, while the other half have white flowers. You now know that the genotype of the test-crossed red flowered parent was: d. Rr Rr x rr r R Rr r rr r Rr rr
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Classical albinism results from a recessive allele. What is the expected ratio for the progeny when a normally pigmented male with an albino father has children with an albino woman? c. normal; albino Nn () nn () n N Nn n nn n Nn nn
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In humans, a widow's peak is caused by a dominant allele, W, and a continuous hairline is caused by a recessive allele w. Short fingers are caused by a dominant allele S and long fingers are caused by a recessive allele s. Suppose a woman with a continuous hairline and short fingers a and man with a widows peak and long fingers have 3 children. One child has short fingers and a widows peak, one has long fingers and a widows peak, and one has long fingers and a continuous hairline. What are the genotypes of the parents? b. Female wwSs; mail Wwss In cocker spaniels, black color (B) is dominant over red (b) and solid color (S) is dominant over spotted (s). If the offspring between BBSS and bbss individuals are mated with each other (BbSs x BbSx), what fraction of their offspring will be expected to be black and spotted? Assume the genes are unlinked: d. 3/16 BbSs x BbSs x = 3/16
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If the same allele has two or more phenotypic effects, it is: d. pleiotropic (just the work) TtSs x TtSs TtSs x ttss 18 T_ 82 tt 22 T_ 200 S_ 22 S_
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Parental 78, 82 = Total: 200 Recombinants 22, 18 = 40 200 = 1/5
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In dogs, erect ears and barking while following a scent are due to dominant alleles; droopy ears and silence while following a scent are due to recessive alleles. A dog homozygous for erect ears and barking is mated to a droopy-eared silent follower. If the two genes are unlinked, the expected F, phenotypic ratios resulting from this mating should be: b. 16:0 EEBB x eebb All EeBb In garden peas, the allele for tall plants is dominant for the allele for short plants. A true breeding tall plant is crossed with a short plant and one of their offspring is test crossed. Out of 20 offspring resulting from the test cross, about _______ should be tall: c. 10 TT x tt Tt x tt F, all Tt Tt tt How does a nucleus in G2 differ from one in the G1 phase? a. G1 has half the amount of DNA as G2 A triploid plant has: a. one extra chromosome b. three of each type of chromosome c. only three chromosomes e. three times the chance of surviving Human males have _____ different types of chromosomes? e. 24 What accounts for the uniform diameter of the DNA molecule? b. A purine bond with a pyrimidine If a double stranded DNA molecule contains 30 percent T it must contain ____ percent G: a. 20 T=A T + A = 60% G=C G + C = 40% For the Hershey-Chase experiment bacteriophage nucleic acids were labeled by carrying out an infection of E. coli cells growing in: c. 32P labeled phosphate The rules formulated by Erwin Chargaff state that: a. A=T and G=C in only molecule of DNA The Hershey-Chase experiment determined that: d. DNA not protein is the heredity material of viruses In Fred Griffith's experiments what happened when heat killed S strain pneumococci were injected into a mouse along with live R strain pneumococci? b. DNA from the heat-killed S was taken up by the live R, converting it to S and killing the mouse.
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The ABO blood groups in humans are determined by a multiple allelic system in which 1A and 1B are co-dominant and are dominant to 1O. If an infant born to a type O mother is also type O, possible phenotype for the father are: a. O or A b. A or B c. O only d. O, A or B e. Impossible to determine In guppies, fan tail is dominant to flesh tail and rainbow colored is dominant to pink. An individual homozygous for both of the dominant traits is crossed with the individual homozygous for both of the recessive traits to produce an F. generation. Heterozygous F. female guppies are then crossed with flesh tailed, pink color homozygous recessive males and the following progeny are observed (401) fantailed pink colored; (399) flesh-tailed rainbow colored; (98) flesh-tailed pink; (102) fan-tailed rainbow. The map distance between these two genes is: a. 80 cm Ff Rr x ffrr F Fan Tail R Rainbow 800 1000 = 8 x 100% ff Flesh Tail rr Pink
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8/10 = 80%
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In humans, Y linked to a gene that produces hairy pinnae. A male with hairy pinnae will pass this trait: a. Usually to his sons, but rarely to his daughters b. Only to his sons c. Only to his daughters d. Only to his grandsons e. To all children White eyes are a recessive sex-linked trait in fruit flies. If a white-eyed female fruit fly is mated to a red-eyed male their offspring should be: c. All white-eyed males, all red-eyed females In tomatoes, tall is dominant to short and smooth fruits are dominant to hairy fruits. A plant homo. for both dominant traits is crossed with a plant homo. for both recessive traits. The F. progeny are crossed with plants homo. for both recessive traits with the following results: 78 tall, smooth; 82 dwarf, hairy; 22 tall; hairy; 18 dwarf, smooth. These date indicate that the genes are: d. Linked and show 20 percent recombination During meiosis, the homologous chromosomes separate and move to opposite poles during: a. anaphase I b. anaphase II c. meiosis I d. metaphase e. telophase II
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If a double-stranded DNA molecule contains 40% T it must contain how much G? a. 10 b. 30 c. 40 d. 50 e. None of the above