GENE TRIVIA CHALLENGE

Now that you are a "GENETIC EXPERT", come test your skills against the ultimate combination of problems. Take out a piece of paper and try to answer the following problems. If you are not able to solve a problem, you may refer back to previous experiments. The answers to the problems are on the next page.

1. In chickens, RrPp is a walnut comb, and rrPP or rrPp is a pea comb. If a hen with a walnut comb is crossed with a rrPP rooster, what is the phenotype and genotype of the offspring?

2. If blue eggs (OO) are dominant, and white eggs are homozygous recessive, give the phenotypes and the genetypes of both the F1 and F2 offspring.

3. Hemophilia is a sex-linked trait carried on the X-chromosome. What are the possible outcomes of both sexes if a normal man marries a hemophilia-carrier woman?

4. A population of 500 pigs contains 150 solid hogs (bb) and 350 spotted hogs (B_). Assume all principles of the Hardy-Weinberg theory apply. Give the phenotypic, gene, and genotypic frequencies of the population.

5. In cattle, incomplete dominance can exist in coat color. A RR genotype gives a red coat, Rr is roan, and rr is white. Polled is dominant (P_) over horned (pp) cattle. If we cross two heterozygous cattle (RrPp), what are the results?

6. From the previous question, what is the proportion of: a) white, polled cattle? b) red, polled cattle? c) roan, polled cattle? d) roan, horned cattle? e) white, horned cattle?

7. If the mean of x = 10 and the mean of y = 8, and the byx = .5, give the equation of the regression line and predict the y value when x = 23.

8. Calculate the mean of x, the variance of x, the standard deviation of x, covariance, rxy, byx when: 

PIG		BACKFAT			WEIGHT
  1		.8			250
  2		.6			241
  3		.9			252
  4		1.1			265

9. A widow's peak on human hairlines is recessive. What are the possible genotypes of the following pedigree?

10. If we have 6 cows born from a red cow and a black heterozygous black bull, what is the probability of getting 5 red and 1 black?

11. What is the probability of getting the order of: red, red, red, red, black, red, red?

12. In the nematode, d (dumpy), u (uncoordinated), and k (knobby) are all recessive genes on the same chromosome. Females heterozygous normal for all three traits were mated to a homozygous recessive male. The results of the offspring are as follows: 

PHENOTYPES	NUMBER
d u k		3
+ u k		392
+ + k		34
+ u +		61
d u +		32
d + k		65
d + +		410
+ + +		3


TOTAL		1000


a.  What is the phase of linkage in the female for:
      1.  d & u
      2.  d & k
      3.  u & k


b.  What is the correct order of the three genes on the chromosome?


c.  What are the map distances between:
      1.  d & u
      2.  d & k
      3.  u & k
d. Calculate the coefficient of coincidence.

 

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