Unformatted text preview: L100 Lecture Quiz #3 ANSWER KEY 1. For each of the two cells below fill in the table below. (2pts each) 2. Somewhere on cells below label sister chromatids (1pt) and a homologous pair (1pt). Cell #1 Cell #2 Crossing over has occurred Yes No (yes / no) Is the cell in Meiosis I or Meiosis I Meiosis II Meiosis I Meiosis II or between the two (I will count Meiosis II since it stages? is only showing one cell) Have the sister chromatids No No split? (yes / no) Have the homologous pairs Yes No split? Cell #1: sister chromatids Cell #2: homologous pair For the two questions below be sure you LABEL your genotype and phenotype ratios so it is clear what the ratios are referring to 3:1 is not enough, what does the 3 stand for and what does the 1 stand for? 3. If two plants, which are heterozygous for the height gene (tall is dominant to short), are crossed, what is the genotypic and phenotypic ratio of their offspring? Show your work (2pts). Parents: Tt * Tt T t T TT Tt t Tt tt Genotype Ratio: Phenotype Ratio 1 : 2 : 1 3:1 ( Tall, short) TT : Tt : tt 4. The seed shape of pea plants varies from being round (dominant) to wrinkled (recessive). If a plant with round seeds is crossed with a plant with wrinkled seeds and some of the offspring are round and some are wrinkled, than what would be the predicted genotypic and phenotypic ratio of their offspring? (Hint: figure out the genotypes of the parents first). (2pts) Parents: Rr * rr Genotypes of the parents: Parent #1 has to have at least one dominant allele because of expressing the dominant trait; and one recessive allele because some of the offspring are homozygous recessive. Parent #2 is homozygous recessive because expressive the recessive phenotype. R r r Rr r Rr Genotype Ratio: 1 : 1 Rr : rr rr rr Phenotype Ratio 1: 1 (equal number of Round and Wrinkled) Round // Wrinkled ...
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- Fall '11
- Genetics, Zygosity, 1pt, rr rr