Unit 8 Test Review
Name ___________Key________________
1. Which of the following is a possible abbreviation for a Rule of Dominance genotype?
A. BC
B. Pp
C. Ty
D. Fg
2. What would be the best way to determine the phenotype of the feathers on a bird?
A. analyze the bird's DNA (genes)
B. look at the bird's feathers
C. look at the bird's beak
D. examine the bird's droppings
3. Which of the following pairs is not correct?
A. kk = hybrid
B. hybrid = heterozygous
C. heterozygous = Hh
D. homozygous = RR
4. The genes present in an organism represent the organism's __________.
A. Genotype
B. Phenotype
C. Physical traits
D. Funny facts
5. Which choice represents a possible pair of alleles in a simple Rule of Dominance situation?
A. k & t
B. K & T
C. K & k
D. K & t
6. How many alleles for one trait are normally found in the genotype of an organism?
A. 1
B. 2
C. 3
D. 4
7. Which statement is not true?
A. genotype determines phenotype
B. phenotype determines genotype
C. a phenotype is the physical appearance of a trait in an organism
D. alleles are different forms of the same gene
8. Which cross would best illustrate Mendel's Law of Segregation? Use page 263-264
A. TT x tt
B. Hh x hh
C. Bb x Bb because it represents Mendel’s famous Hybrid F1 crosses
D. rr x rr
9. In the cross Yy x Yy, what percent of offspring would have the same phenotype as the parents?
A. 25%
B. 50%
C. 75%
D. 100%
10. In a certain plant, purple flowers are dominant to red flowers. If the cross of two purple-flowered plants produces
some purple-flowered and some red-flowered plants, what is the genotype of the parent plants?
A. PP x Pp
B. Pp x Pp
C. pp x PP
D. pp x pp
Base next four questions on the following information:
A white-flowered plant is crossed with a pink-flowered plant. All of the F1 offspring from the cross are white.
11. Which phenotype is dominant? White because all of the offspring are white.
12. What would the genotypes of the original parent plants be? Use any letter you choose
13. What is the genotype of all the F1 offspring? Use the same letter as question 21.
WW x ww
Ww
14. What would be the percentages of genotypes & phenotypes if one of the white F1 plants is crossed with
a pink-flowered plant? Hint: Use a Punnett Square!!!
Ww x ww would have 50 % Ww (White) and 50 % ww (Pink)
15. Which of Mendel's Laws is/are illustrated in the above questions?
Law of Segregation (there was random pairing and there were different possibilities and Rule of
Dominance because the dominant allele masked the recessive.
16. The outward appearance (gene expression) of a trait in an organism is referred to as:
A. Genotype
B. Phenotype
C. an allele
D. independent assortment
17. Mendel formulated his Law of Segregation after he had:
A. studied F1 offspring
B. studied F2 offspring
C. produced mutations
D. produced hybrids
18. Which cross would produce phenotypic ratios that would illustrate the Rule of Dominance?
A. TT x tt
B. TT x Tt
C. Tt x Tt
D. tt x tt
19. The mating of two curly-haired brown guinea pigs results in some offspring with brown curly hair, some
with brown straight hair, some with white curly hair, and even some with white straight hair. This
mating illustrates which of Mendel's Laws?
A. Rule of Dominance
B. Law of Segregation
C. Law of Independent Assortment
D. Law of Super Storey
20. An animal that has a genotype of two upper letters, such as AA is called ___.
A. Homozygous Recessive
B. Heterozygous Dominant
C. Homozygous Dominant
D. Heterozygous Recessive
21. An animal that has a genotype of two lowercase letters, such as aa is called ________.
A. Homozygous Recessive
B. Heterozygous Dominant
C. Homozygous Dominant
D. Heterozygous Recessive
22. If an organism is said to be a hybrid, that means they are…?
A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous
D. True-breeding
Generations: The Disappearance and Reappearance of a Recessive Trait
23. What is the result every time a homozygous dominant trait is crossed with a homozygous recessive trait?
Using R and r, prove your answer.
____RR___ x ___rr___
P1
GR _____100% Rr__________
PR____100% Dominant Trait___
F1
What happens to the recessive trait? It gets masked by the Dominant Trait
Label the P1 generation and the F1 generation in questions above
24. What is the result if we allowed the offspring of this cross to self-pollinate (have two individuals cross
from the F1 generation)? Use a Punnett square in your answer.
___Rr___ x____Rr___
F1
F2
GR __25% RR, 50% Rr, 25% rr_____
PR__25% Homozygous Dom, 50% Heterozygous, 25% Homozygous Rec.
What happens to the recessive trait? It shows back up in a small percentage.
Label the F1 generation and the F2 generation in questions above.
How Can a Phenotype Be Determined?
25. By looking at a black dog, can you tell exactly what its genotype is? __Nope_______
26. If we use B= black and b=white, write down the two possible genotypes of a black dog ____BB______
and ___Bb____. Double check you answer to question 1.
27. How could be actually find out the black dogs genotype? Think about what we have been learning to do!
Prove your answer. You could use the genotypes of the parent dogs and use a Punnett Square to
figure out possibilities for the genotype of the offspring. It would only work if you knew the other
parents genotype exactly and then you can breed several F1 generations to see if purebreds result.
28. Where do an individual’s alleles come from?
For every trait in an organism, they inherit one allele from the mother and one from the father.
29. Describe the three rules/laws Mendel discovered.
Rule of Dominance – Dominant allele masks the recessive allele, recessive is only seen when purebred
Law of Segregation – random pairing of alleles (Bb X Bb can yield BB, Bb, or bb)
Law of independent Assortment – different traits are inherited independently. Eye color does not
determine hair color.
30. What is the difference between homozygous dominant, homozygous recessive and heterozygous? Give
an example of each.
Homozygous Dominant – Purebred with two dominant allele (BB)
Homozygous Recessive – Purebred with two recessive alleles (bb)
Heterozygous – hybrid with one dominant and one recessive allele (Bb)
31. What is the difference between genotypes and phenotype?
Genotype – actual alleles/genes involved, denoted by using letters
Phenotype – what we physically see with our eyes.
You cannot always tell a genotype from looking at a phenotype, but you can ALWAYS tell a phenotype from a
genotype.
32. Categorize the following as phenotypes or genotypes:
Tt
Brown
____Geno__ __Pheno___
bb
Spotted
Slow
Ss
XX
____Geno___ ____pheno____ ____pheno____ ___geno____ ___Geno___
33. What type of organism did Mendel choose to use in his research? Why did he choose them?
Pea Plant because they reproduce sexually, have male and female parts, and they are easy to
pollinate and cross-pollinate. He could control their pollination very easily.
34. Cross homozygous dominant tall plant with a heterozygote:
R
r
R
RR
Rr
R
RR
Rr
35. Determine the F2 generation if the P1 = homozygous dominant fast organism crossed with a slow
organism
F
F
F
f
P1
F1
f
Ff
Ff
F FF
Ff
F1
F2
f
Ff
Ff
f
Ff
ff
36. If you found 16 pea plants and half of them were tall and half of them were short, what were the original
parents’ genotypes? They would have to have been Tt x tt.
Use the following pea plant traits to perform the problems.
Pea shape
Round=R
Flower color
Purple=P
Plant height
Tall=T
Pod shape
Smooth=N
Wrinkled=r
White=p
Short=t
Constricted=n
37. What would the genotypes be for a plant that is....
A. heterozygous round ___Rr___
B. short ___tt__
C. homozygous tall ___TT____
D. white flowered ___pp____
E. heterozygous purple flowers ____Pp____
F. homozygous round peas ____RR____
38. What would the phenotype be for a plant that is…
A. RR = __Round Pea Shape__
B. Nn = __Smooth Pod Shape__
C. nn = __Constricted Pod Shape__
D. Tt = __Tall Plant Height__
E. Pp = __Purple Flower____
39. Do a Punnett square for Rr x rr
genotype ratio ___50% Rr, 50% rr_____
phenotype ratio _50% Round, 50 % Wrinkled__
40. Do a Punnett square for Rr x Rr
genotype ratio __25% RR, 50% Rr, 25% rr__
phenotype ratio _75% Round, 25% Wrinkled___
41. How much of your genetic information comes from your mother? __50%____ father? ___50%___
42. A recessive trait can only be visible when it is (Homozygous or Heterozygous) for a specific trait.
43. Explain why BB x RR would not be a possible cross.
The alleles (BB) should be matched up with other letter Bs and the same for the Rs. The Bs code
for one trait and the Rs code for another trait. B and R are not for the same trait.
44. What would be a possible cross involving either of the alleles in question 7?
BB x bb, BB x Bb, Bb x Bb, RR x Rr, RR x rr, Rr x Rr
45. The gene or letter combination for a trait is called a ______Genotype__________
46. The physical appearance or description of a trait is called a _________Phenotype__________
47. What is a genotype for an organism that is heterozygous? (Use any letter.) ___Hh____
48. A visible, observable trait is a _____Dominant_______ trait.
49. A hidden trait that is masked by the observable trait is called a _____Recessive_______ trait.
50. Select the word that does not belong: heterozygous, homozygous, hybrid.
51. Select the word that does not belong: homozygous, heterozygous, purebred.
52. A variation of a gene is called an ______Allele________.
53. In rabbits brown fur (B) is dominant over white fur (b). If one parent, in a cross, was Bb and had brown
fur, the brown fur would be the parent’s ____Phenotype____ and Bb would be the
____Genotype_____.