The astronaut looked out the porthole. Where a yellow orb should've hung was blackness. A voice crackled through the speaker, "Sorry, but we've made an error . . rather trivial, actually. But instead of landing on the moon, I'm afraid you are headed for Pluto. We want to assure you, however, that we here at Ground Control do understand the principles of navigation."

Alas, your understanding of genetics principles must be demonstrated on your General Purpose Answer Sheet, form no.-16504. Please be sure not to mark on the question sheets, but to mark your answers on the form only. Each question is worth four points. All recessive alleles are underlined. Good Luck!

The correct answer for each question is denoted by the blinking characters.
If your browser cannot detect the blinking characters, check the answer table at the bottom of this test.

1. In the following example, B is completely dominant over its recessive allele b. In addition, Y is a lethal gene (i.e., yellow fur in mice). Thus, Yy determines yellow and YY is lethal.
   1. If we perform the following cross, Bb Yy x Bb Yy, what phenotypic ratio is expected among the viable progeny?
      1. 2:1
      2. 3:1
      3. 6:3:2:1
      4. 9:3:3:1
      5. 18:9:6:6:3:3:2:1

2. In sesame, both the number of seed pods per leaf axil and the shape of the leaf are genetically controlled. The one-pod (P) condition is dominant to the three-pod (p) condition, and normal leaf (W) is dominant to wrinkled leaf (w). The two characters are inherited independently and there is no gene interaction between the gene pairs. Recessive alleles are underlined.
   2. A 1-pod, normal plant was crossed with a 1-pod, wrinkled plant and the following progeny were produced:

      110 1-pod, normal : 113 1-pod, wrinkled : 33 3-pod, normal : 38 3-pod, wrinkled

      The genotypes of the plants crossed would be:

      1. Pp WW x pp ww
      2. PP Ww x pp Ww
      3. Pp Ww x Pp ww
      4. Pp ww x pp Ww
      5. Pp Ww x pp Ww

3. Consider the following genetically controlled biosynthetic pathway in a hypothetical plant:

   	allele A		allele B
   	enzyme A		enzyme B
   white		orange		maroon

   Assume that orange pigment is coded for in the presence of the dominant allele A, but the plant remains white in its absence; and the dominant allele B but not the recessive allele b codes for the enzyme necessary to catalyze the conversion of the orange pigment to a maroon pigment.
   3. What phenotypes and proportions can be expected in the progeny of the AaBb x aaBb cross?
      1. 9 orange : 7 white
      2. 4 maroon : 3 orange : l white
      3. 12 maroon : 3 orange : l white
      4. 4 white : 3 maroon : 1 orange
      5. 9 maroon : 4 white : 3 orange

   4. The following phenotypic ratio would be approximated in the F₂ from a mating between two maroon F₁ individuals:
      1. 9:7
      2. 13:3
      3. 9:4:3
      4. 12:3:1
      5. 9:3:3:1

   5. The specific type of epistatic gene interaction involved would be:
      1. duplicate recessive
      2. dominant
      3. dominant and recessive
      4. duplicate dominant
      5. recessive

4. 6. If you crossed a walnut-combed hen with a rose-combed rooster who are both heterozygous at one gene locus, but homozygous at the other gene locus, what is the probability of producing a walnut-combed chick?
      1. 1/1
      2. 1/2
      3. 1/4
      4. 9/16
      5. None of the above

5. 7. If an organism's genotype is Aa BB Cc dd Ee, how many different types of gametes will it (or can it) make?
      1. 3
      2. 8
      3. 16
      4. 27
      5. None of the above

   8. If an individual of the above genotype (Aa BB Cc dd Ee) were crossed with another of the genotype Aa Bb Cc DD Ee, how many different progeny phenotypes could they produce?
      1. 3
      2. 8
      3. 16
      4. 27
      5. None of the above

   9. How many different progeny genotypes could they produce? (Same cross as in question # 8).
      1. 3
      2. 8
      3. 16
      4. 27
      5. None of the above

6. P __ = polled; pp = horned; RR = red; RR' = roan; R'R' = white
   A white bull heterozygous for polled is mated to roan females heterozygous for polled. Remember polled is dominant to horned.
   10. What is the phenotypic ratio of the offspring?
       1. 2:1:1
       2. 3:3:1:1
       3. 3:1
       4. 9:3:3:1
       5. 2:2:1:1:1:1

   11. What is the genotypic ratio of the offspring?
       1. 2:2:1:1:1:1
       2. 2:1:1
       3. 3:3:1:1
       4. 3:1
       5. 9:3:3:1

7. Two homozygous strains of corn are hybridized. They are distinguished by two different pairs of genes, all of which assort independently and produce an independent phenotypic effect. The F₁ hybrid is selfed to give an F₂.
   12. How many of the total possible different genotypes in the F₂ will be homozygous at both gene loci?
       1. 1
       2. 2
       3. 3
       4. 4
       5. 5

   13. If all gene pairs act in a dominant-recessive fashion, what proportion of the F₂ will show all recessive phenotypes?
       1. 0
       2. 1/2
       3. 1/4
       4. 1/8
       5. 1/16

8. You have a pet, a duck-billed platypus, with the following genotype:
   AA Bb cc Dd Ee FF gg Hh Ii JJ
   14. How many heterozygous allele pairs would be involved if this platypus were to be used in an F₁ breeding experiment?
       1. 1
       2. 3
       3. 5
       4. 12
       5. 42

   15. If this F₁ platypus were to be testcrossed, how many different phenotypes could be observed in the testcross progeny?
       1. 32
       2. 243
       3. 1,024
       4. 59,049
       5. None of the above

   16. How many different F₂ genotypes of baby platypi could be produced if two F₁ individuals were crossed?
       1. 32
       2. 243
       3. 1,024
       4. 59,049
       5. None of the above

9. A testcross involving an F₁ parent results in a testcross progeny phenotypic ratio of 1:1:1:1:1:1:1:1
   17. What fraction of the gametes produced by the F₁ individuals would be completely recessive for the gene (or all the genes) in question?
       1. 1/2
       2. 1/3
       3. 1/4
       4. 1/8
       5. None of the above

   18. If two F₁ individuals were crossed to produce an F₂ generation, how many different phenotypes could be present in the F₂ generation?
       1. 4
       2. 8
       3. 27
       4. 64
       5. None of the above

10. 19. A pea of unknown genotype is grown from a seed showing the dominant traits round and yellow. When we cross-pollinate this plant with another that is known to be heterozygous for both gene pairs, the resulting progeny are: (round = W, wrinkled = w, G = yellow, g = green).
        54 round - yellow
        19 round - green

        What is the genotype of the unknown plant?

        1. WWGg
        2. WwGg
        3. WwGG
        4. WWGG
        5. None of the above

11. 20. If you crossed two round peas of unknown genotype and all the progeny are round, what genotypes are indicated for the unknowns?
        1. Both are homozygous RR
        2. One is RR and the other is Rr
        3. At least one is RR
        4. At least one is Rr
        5. Both are Rr

12. 21. The following applies to the "Principle of Independent Assortment".
        1. All possible combinations of alleles are produced in equal proportions.
        2. Alleles of each gene separate during gamete formation and enter different gametes, so that half the gametes carry one allele and half carry the other.
        3. Either allele of one gene pair enters a gamete with either allele of any other gene pair.
        4. Is Mendel's First Law
        5. More than one of the above.

    22. The genus and species of the organism in which Gregor Mendel studied seven contrasting traits was:
        1. Drosophila melanogaster
        2. Stevus doylus
        3. Gallus domesticus
        4. Homo sapiens
        5. Pisum sativum

13. 23. In the following example, the B and C alleles are completely dominant over their recessive alleles b and c. In addition, R and R' are a semidominant pair of alleles and the RR' heterozygote shows an intermediate phenotype (i.e., pink in snapdragons). If we perform the following cross: BbCcRR' x BbCcRR'

        What is the probability of an offspring showing dominant traits B and C and the intermediate trait coded for by RR'?

        1. 2/3
        2. 9/16
        3. 9/32
        4. 9/64
        5. None of the above

    24. From the above cross (question # 23), how many different phenotypes could be found among the offspring?
        1. 4
        2. 8
        3. 12
        4. 16
        5. None of the above

14. 25. An unknown round pea is testcrossed to rr and only one pod of peas is produced containing 5 round peas. We cannot be absolutely certain of the genotype of the unknown plant with such a small number of progeny.

        What is the probability that the unknown plant was Rr and we failed to detect the recessive allele among the five testcross progeny, or what is the probability of getting R from Rr five times in a row?

        1. 0
        2. 1/2
        3. 1/5
        4. 1/16
        5. None of the above

---

Correct Answers for this Test (question # -- answer)

1 -- C	6 -- B	11 -- A	16 -- B	21 -- E
2 -- C	7 -- B	12 -- D	17 -- D	22 -- E
3 -- D	8 -- B	13 -- E	18 -- B	23 -- C
4 -- C	9 -- E	14 -- C	19 -- A	24 -- C
5 -- E	10 -- B	15 -- A	20 -- C	25 -- E

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