BioSc 231
General Genetics
Exam 1
Name __________________________________
Multiple Choice. (1 point each)
1. _____ An allele is ___.
A. one of the bases in DNA
B. an alternate form of a gene
C. another term for epistasis
D. present only in males and is responsible for sex determination
E. found in mitochondria but not in nuclei
2. _____ What is the probability that on four flips of a coin, heads will occur on three flips and tails on 1?
A. 1/4
B. 1/2
C. 3/16
D. 1/8
E. insufficient information to answer this question
3. _____ What would be the dimensions of a Punnett square for the cross Ww x ww?
A. 4 x 4
B. 2 x 2
C. 2 x 1
D. 1 x 1
4. _____ In dihybrid crosses, the ratio 9:3:3:1 indicates ___.
A. Codominance
B. Independent assortment
C. Intermediate dominance
D. Three alleles for each trait
5. _____In a cross of a round hybrid pea with a true breeding round parent (Ww x WW), what genotypic proportions would be
observed in the offspring?
A. Half heterozygous, half homozygous dominant
B. Half round, half wrinkled
C. All heterozygous
D. All round
6. _____ The fundamental Mendelian process which involves the separation of contrasting genetic elements at the same locus would
be called ___.
A. segregation
B. independent assortment
C. continuous variation
D. discontinuous variation
E. dominance or recessiveness
7. _____ Probabilities are calculated using the addition rule when they ___.
A. Are equally likely
B. Are independent
C. Are mutually exclusive
D. Occur disproportionately
8. _____ Probabilities are calculated using the multiplication rule when they ___.
A. Are equally likely
B. Are independent
C. Are mutually exclusive
D. Occur disproportionately
9. _____ What ratios typically result from crosses dealing with a single genetic locus?
A.
B.
C.
D.
E.
9:3:3:1, 1:2:1
1:1:1:1, 1:4:6:4:1
3:1, 1:1, 1:2:1
9:7, 12:3:1
15:1, 1:2
10. _____There are three different genotypes resulting from a monohybrid cross. How many different genotypes would there be
resulting from a dihybrid cross?
A. 4
B. 8
C. 9
D. 16
11. _____ The base thymine is always paired with ___.
A. Adenine
B. Guanine
C. Cytosine
D. Thymine
12._____ The sequence of one strand of DNA is 5’ TCGATC 3’. The sequence of the complementary strand would be ___.
A. 5’ AGCTAG 3’
B. 5’ TCGATC 3’
C. 5’ CTAGCT 3’
D. 5’ GCTAGC 3’
E. 5’ GATCGA 3
13. _____ Starting with a cross between AA and aa, the proportion of heterozygotes in the F2 progeny will be ___.
A. 1/8
B. 1/4
C. 1/3
D. 1/2
E. All heterozygotes
14. _____ Genotype is to DNA as phenotype is to
A. Genotype
B. Proteins
C. Expressivity
D. RNA
E. Mutation
15. _____ Albinism, lack of pigmentation in humans, results from an autosomal recessive gene designated a. Two parents with
normal pigmentation have an albino child. What is the probability that their next child will be albino? What is the probability that the
next child will be an albino girl?
A. 1/2; 1/4
B. 1/4; 1/2
C. 1/4; 1/8
D. 1/8; 1/4
16. _____ Starting with a P generation with the following genotypes (AABB x aabb). Based on classical Mendelian inheritance, what
is the expected phenotypic ratio observed among the F2 progeny?
A. 9:3:3:1
B. 1:2:1
C. 3:1
D. 1:1
E. 1:1:1:1
17. _____ In the previous question, if A = plain fur and a = spotted fur and B = Long ears and b = short ears, what phenotypic class
would be observed in the highest proportion in the F2 generation?
A. spotted - short ears
B. plain - short ears
C. spotted - long ears
D. plain - long ears
18. _____ A species of mice can have gray or black fur and long or short tails. A cross between black-furred, long-tailed mice and
gray-furred, short-tailed mice produce all black-furred, long-tailed offspring. Using the gene symbols G for black, g for gray, S for
long and s for short, what would be the genotype of a gray-furred, short-tailed mouse?
A. GGSS
B. ggSS
C. ggss
D. GgSs
E. Ggss
19. _____ Referring to question 18, how many different gametes will the black-furred, long-tailed P1 mice produce?
A. 1
B. 2
C. 4
D. 16
20. _____ Referring to question 18, how many different gametes do the black-furred, long-tailed F1 mice produce?
A. 1
B. 2
C. 4
D. 16
21. _____ What would be the dimensions of a Punnett Square depicting a dihybrid cross?
A. 1 x 4
B. 2 x 4
C. 4 x 4
D. 2 x 2.
22. _____ What would be the minimum dimensions of a Punnett square of a test cross with a dihybrid parent who is heterozygous at
both loci?
A. 4 x 4
B. 4 x 1
C. 2 x 4
D. 4 x 2
E. 2 x 2
23. _____ To determine if an organism with a dominant phenotype is heterozygous, one can perform a ___.
A. reciprocal cross
B. dihybrid cross
C. test cross
24. _____ In a F1 dihybrid cross (WwGg X WwGg) where W = round, w = wrinkled, G = yellow and g = green, what is the
probability of obtaining an individual that is wrinkled, green and true-breeding?
A. 1/16
B. 1/2
C. 9/16
D. 3/16
E. 1/4
25. _____ What genotype is present most often among the progeny (F2) of a dihybrid cross (AaBb X AaBb)?
A. AaBb
B. AABb
C. AABB
D. aabb
E. AAbb
26. _____ Barney and Betty are about to have their first child. They both have "normal" feet but Barney's father has flat feet and
Betty has a child from a previous marriage who has flat feet. What is the probability that they will have a boy with flat feet?
A. 1/2
B. 1/4
C. 1/8
D. 3/4
E. 3/8
27. _____ In the previous question, Barney and Betty learn that they will actually have twins - dizygotic twins. What is the
probability that they will have both a boy and a girl, both of whom are flat footed?
A. 1/4
B. 1/8
C. 1/16
D. 1/32
E. 1/64
28. _____ Microbiologist who demonstrated that DNA was the genetic material.
A. Oswald Avery
B. Herbert Boyer
C. Rosalind Franklin
D. Barbara McClintock
E. James Watson
29. _____ Geneticist who discovered genes that could actually "move" from generation to generation.
A. Oswald Avery
B. Herbert Boyer
C. Rosalind Franklin
D. Barbara McClintock
E. James Watson
30. _____ Biochemist who discovered restriction endonucleases, one of the key tools for genetic engineering.
A. Oswald Avery
B. Herbert Boyer
C. Rosalind Franklin
D. Barbara McClintock
E. James Watson
Short Answer. (1 point each)
What type of cross produces a 1:1:1:1 phenotypic ratio?
In your own words, what is the meaning of the term allele?
Black and white coloration in cows is dominant to brown and white. Black and white cows were crossed over several years and the
following progeny were produced: 8 black and white and 3 brown and white. What is the most probable genotype of each parent?
What is the expected genotypic and phenotypic ratio expected for the progeny in the previous question?
A certain type of congenital deafness in humans is caused by a rare autosomal dominant gene. In a mating involving a deaf man and a
deaf woman, could all the children have normal hearing? Explain.
The white eye gene of Drosophila is recessive and sex-linked. Assume that a white-eyed female is mated to a wild-type male. What
would be the phenotypes of the offspring?
What would be the phenotypes of the reciprocal cross?
Give one reason why the relationship between genes and traits is often complex.
In a cross between homozygous wild-type female Drosophila and yellow-bodied males all of the F1’s were phenotypically wild type.
The F2 generation (resulting from matings of the F1’s) had 356 wild-type offspring and 123 yellow bodied offspring. However, all
240 females were wild-type and of the 239 males, 116 were wild-type and 123 were yellow bodied. How is the yellow-bodied trait
inherited?
I have six sisters and one brother. My brother is the oldest and I am child number 6. What is the probability of parents having 6 girls
and 2 boys in the order I just described?
Believe it or not, my aunt and uncle had 8 children in exactly the same order but then spoiled it by having another son :-) What is the
probability that the 9th child was a boy?
In Pokemon genetics (sorry, I have a 7 year old) the symbol Y is for yellow Pikachu (see picture below), y is for white, L is for jagged
tail and l is for straight. In the cross YyLl x YyLl what fraction of the Pikachu that will be:
A. Yellow
B. Straight tail
C. White and straight tail
D. Yellow and straight tail
E. Yellow and jagged tail
Pedigree Analysis (5 points each)
A.
Examine pedigree A above. How is the trait inherited?
What are the genotypes of the following individuals
I-1
I-2
II-1
II-3
II-4
II-6
III-5
III-10
B.
Examine pedigree B above. How is the trait inherited?
What is the genotype of the following individuals?
I-1
I-2
I-3
I-4
II-1
II-2
II-3
II-4
Short “essay” Answer one of the following two questions (5 possible bonus points for correctly answering both)
The ferocious Jackalope (pictured at right) is a hybrid of a jackrabbit and an antelope.
Jackalopes may be either long horned or short horned. The following data was obtained
through controlled matings.
F1 Progeny
P1 cross
# long horn
# short horn
(a) long horn x long horn
39
2
(b) long horn x short horn
42
0
(c) short horn x short horn
0
40
How are the long and short horn traits inherited?
Predict the results of the F1 x F1 mating from cross (b)
What are the possible explanations for the 2 short horned jackalopes from cross (a)?
Alice and Ralph have decided to start a family. Ralph has normal vision but he has a brother who has a rare inherited form of
blindness. Neither of Ralph's parents nor his two sisters are blind. Alice has two brothers and two sisters with normal vision and
neither of her parents are affected. Draw a pedigree to illustrate the situation using the standard symbols for males, females, affected,
unaffected, carriers etc. Alice and Ralph would like to have two children. What is the probability that either of their children will be
blind? What is the probability that either of their children will be carriers? Explain your answers.