BIOL 1406 EXAM 4 CHAPTERS 11-14 1) What was the most significant conclusion that
ID: 220009 • Letter: B
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BIOL 1406 EXAM 4 CHAPTERS 11-14 1) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A) There is considerable genetic variation in garden peas. B) Traits are inherited in discrete units, and are not the results of the "blending" of traits. C) Recessive genes occur more frequently in the F1 generation than do dominant ones. D) An organism that is homozygous for many recessive traits is at a disadvantage. 2) Which of the following statements describes one difference between the law of independent assortment and the law of segregation? A) The law of independent assortment explains the segregation of two or more genes relative to one another B) The law of segregation explains the segregation of two or more genes relative to one another. C) The law of segregation requires having two or more generations to describe. D) The law of segregation is accounted for by anaphase of mitosis. 3) Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? A) that each offspring has the same alleles for each of two traits B) that the trait shows incomplete dominance C) that a blending of traits has occurred D) that the parents were both heterozygous for a single trait 4) When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? A)0% B) 25% C) 5096 D) 75% 5) Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? A) No genes interacted to produce the parental phenotype. B) Each allele affected phenotypic expression. C) Phenotype was not dependent on genotype. D) One allele was dominant.Explanation / Answer
1. B. Traits are inherited in discrete units, and are not the result of blending of traits. This is clearly shown by "Law of segregation of Mendel" that factors do not blend but segregate at time of gamete formation.
2.A. The law of independent assortment explains the segregation of two or more genes relative to one another.
3. D. The parents were both heterozygous for a single trait.
4. C. homozygous recessive(eg. rr) and heterozygote (eg. Rr) is crossed then, 50% chance of homozygous recessive phenotype.
5. D. Since one allele is dominant it masks the effect of recessive allele and the F1 resembles dominant one phenotypically.
6. D. BbTt produce 4 types of gamete( BT, Bt, bT, bt) and BBtt produce one gamete Bt. On crossing they produce black colour and long tail in fraction of 1/2.
7. D. heterozygous plant(Tt) and homozygous dominant (TT) is crossed, then % of offspring short is 0%.
8. A. AABBCC produce gamete ABC and AabbCc produce 4 types of gamete AbC, Abc, abC, abc hence fraction having parental genotype is 1/4.
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