Q1) What does Mendel's postulate of segregation state?
Q2) What does Mendel's postulate of independent assortment state?
Q3) a. What are the genotypes of the parents in cross [b] or [c]?
b. Draw a Punnett Square which represents the cross & give the expected phenotypic ratios of the offspring.
Q4) Draw how the chromosomes of a diploid cell with a total of 4 chromosomes line up on the metaphase plate in (a) mitosis & (b) meiosis I. Make certain the chromosomes are distinguishable, e.g. one is short while the other is long.
Q5) Heterozygous black guinea pigs (Bb) are crossed among themselves. What is the probability of producing two black & three white offspring in any order? Show your work!
Q6) The majority of corn grown in this country is starchy and is fed to cattle. Shriveled or shrunken corn kernels (when allowed to dry) result from defects in the process whereby starch is synthesized from sugar in the endosperm, leading to sweet (and therefore edible by people!) kernels. Two of the most common mutations found in sweet corn are sugary 1 (su1) and shrunken2 (sh2), which are recessive alleles of two different genes. If the proteins encoded by both genes (Su1 and Sh2) are both required for the conversion of sugar to starch, what ratio of starchy to sweet offspring do you expect in the F2 generation of a cross between a sui/sui plant and a sh2/sh2 plant?
Q7) Describe the chromosomal abnormalities in the following syndromes:
a. Turner
b. Klinefelter's
c. Down
Q8) Humans have 46 chromosomes in each somatic cell.
a. How many chromosomes does a child receive from its father?
b. How many autosomes and how many sex chromosomes are present in each somatic cell?
c. How many chromosomes are present in a human ovum?
d. How many sex chromosomes are present in a human ovum?
Q9) One oak tree cell with 14 chromosomes undergoes mitosis. How many daughter cells are formed, and what is the chromosome number in each cell?
Q10) a. What are the four major stages of the cell cycle?
b. Which stages are included in interphase?
c. What event distinguishes S phase?
Q11) Is there any reason that mitosis could not occur in a cell whose genome is haploid? Why or why not? Relate your answer to the way chromosomes line up for metaphase in mitosis.
Q12) In the moss Polytrichum commune, the haploid chromosome number is 7. A haploid male gamete fuses with a haploid female gamete to form a diploid cell that divides and develops into the multicellular sporophyte. Cells of the sporophyte then undergo meiosis to produce haploid cells called spores. What is the probability that an individual spore will contain a set of chromosomes all of which came from the male gamete? Assume no recombination (crossover).
Q13) Somatic cells of chimpanzees contain 48 chromosomes.
How many chromatids and chromosomes are present at (a) anaphase of mitosis, (b) anaphase I of meiosis, (c) anaphase II of meiosis, (d) G1 prior to mitosis, (e) G2 prior to mitosis, (f) G1 prior to meiosis I, and (g) prophase of meiosis I?
How many chromatids and chromosomes are present in (h) an oogonial cell prior to S phase, (i) a spermatid, (j) a primary oocyte arrested prior to ovulation, (k) a secondary oocyte arrested prior to fertilization, (1) a second polar body, and (m) a chimpanzee sperm?
Q14) Imagine you have two pure-breeding lines of canaries, one with yellow feathers and one with brown feathers. In crosses between these two strains, yellow female x brown male gives only brown sons and daughters, while brown female x yellow male gives only brown sons and yellow daughters. Propose a hypothesis to explain these results.
Q15) In Drosophila, the autosomal recessive brown eye color mutation displays interactions with both the X-linked recessive vermilion mutation and the autosomal recessive scarlet mutation. Flies homozygous for brown and simultaneously hemizygous or homozygous for vermilion have white eyes. Flies simultaneously homozygous for both the brown and scarlet mutations also have white eyes. Predict the F1 and F2 progeny of the following true-breeding parents:
a. vermilion females x brown males
b. brown females x vermilion males
c. scarlet females x brown males
d. brown females x scarlet males
Q16) Each of the four pedigrees shown here represents a human family within which a genetic disease is segregating. Affected individuals are indicated by filled-in symbols. One of the diseases is transmitted as an autosomal recessive condition, one as an X-linked recessive, one as an autosomal dominant, and one as an X-linked dominant. Assume all four traits are rare in the population.
a. Indicate which pedigree represents which mode of inheritance, and explain how you know.
b. For each pedigree, how would you advise the parents of the chance that their child (indicated by the hexagon shape) will have the condition?
Q17) The ancestry of a white female tiger bred in a city zoo is depicted in the following pedigree. White tigers are indicated with unshaded symbols. (As you can see, there was considerable inbreeding in this lineage. For example, the white tiger Mohan was mated with his daughter). In answering the following questions, assume that "white" is determined by allelic differences at a single gene and that the trait is fully penetrant. Explain your answers by citing the relevant information in the pedigree. Could white coat color be caused by a:
a. Y-linked allele?
b. dominant X-linked allele?
c. dominant autosomal allele?
d. recessive X-linked allele?
e. recessive autosomal allele?
