Unit 1B Review Sheet
Name ______KEY______________________
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The gene or letter combination for a trait is called a ______Genotype__________
The physical appearance or description of a trait is called a _________Phenotype__________
What is a genotype for an organism that is heterozygous? (Use any letter.) ___Hh____
A visible, observable trait is a _____Dominant_______ trait.
A hidden trait that is masked by the observable trait is called a _____Recessive_______ trait.
Select the word that does not belong: heterozygous, homozygous, hybrid.
Select the word that does not belong: homozygous, heterozygous, purebred.
A variation of a gene is called an ______Allele________.
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_____.
10. Which of the following is a possible abbreviation for a Rule of Dominance genotype?
a) BC
b) Pp
c) Ty
d) Fg
11. 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
12. Which of the following pairs is not correct?
a) kk = hybrid
b) hybrid = heterozygous
c) heterozygous = Hh
d) homozygous = RR
13. The genes present in an organism represent the organism's __________.
a) Genotype
b) Phenotype
c) Physical traits
d) Funny facts
14. 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
15. How many alleles for one trait are normally found in the genotype of an organism?
a) 1
b) 2
c) 3
d) 4
16. 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
17. 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
18. 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%
19. 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.
20. Which phenotype is dominant? White because all of the offspring are white.
21. What would the genotypes of the original parent plants be? Use any letter you choose
WW x ww
22. What is the genotype of all the F1 offspring? Use the same letter as question 21.
Ww
23. 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)
24. Which of Mendel's Laws is/are illustrated in the above questions?
Law of Segregation and Rule of Dominance
25. 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
26. Mendel formulated his Law of Segregation after he had:
a) studied F1 offspring
b) studied F2 offspring
c) produced mutations
d) produced hybrids
27. Which cross would produce phenotypic ratios that would illustrate the Law of Dominance?
a) TT x tt
b) TT x Tt
c) Tt x Tt
d) tt x tt
28. 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
29. An animal that has a genotype of one uppercase letter and one lowercase letter, such as Aa is called
__.
A) Homozygous Recessive
C) Heterozygous Dominant
B) Homozygous Dominant
D) Heterozygous Recessive
30. An animal that has a genotype of two upper letters, such as AA is called ___.
A) Homozygous Recessive
C) Heterozygous Dominant
B) Homozygous Dominant
D) Heterozygous Recessive
31. An animal that has a genotype of two lowercase letters, such as aa is called ________.
A) Homozygous Recessive
C) Heterozygous Dominant
B) Homozygous Dominant
D) Heterozygous Recessive
32. If an organism is said to be a hybrid, that means they are…?
A) Homozygous dominant
B) Homozygous recessive
C) Heterozygous
D) True-breeding
33. A punnett square is used to determine the…
A) result of Meiosis I
C) result of segregation
B) possible outcomes of a cross
D) actual outcome of a cross
34. A couple has two children, both of whom are boys. What is the chance that the parents’ next child
will be a boy?
A) 0%
B) 25%
C) 50%
D) 100%
35. If the offspring from the testcross are half white and half black, you would conclude that the black
hamster’s genotype would be? (Given B is black and b for white.)
A) BB
B) bb
C) Bb
D) None of the above
36. The passing on of traits from parents to offspring is called ___________.
A) Genetics
B) Heredity
C) Inbreeding
D) Gene Splicing
Generations: The Disappearance and Reappearance of a Recessive Trait
1. 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_________
What happens to the recessive trait? It gets masked by the Dominant Trait
2. 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.
3. Label the P1 generation, the F1 generation and the F2 generation in questions above.
How Can a Phenotype Be Determined?
1. By looking at a black dog, can you tell exactly what its genotype is? __Nope_______
2. 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.
3. 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.
Flower Parts
Label the following flower parts: anther, filament, pistil, stigma, stamen, and ovary.
Anther
Stigma
Stamen
Pistil
Filament
Ovary
On what structure would you find the pollen grains? ____Anther_____
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
1. 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____
2. What would the phenotype be for a plant that is…
A. RR = __Round Pea Shape__
B. Nn = __Smooth Pod Shape__
C. Nn = __Smoth Pod Shape__
D. Tt = __Tall Plant Height__
E. Pp = __Purple Flower____
3. Do a punnett square for Rr x rr
genotype ratio ___50% Rr, 50% rr_____
phenotype ratio _50% Round, 50 % Wrinkled__
4. Do a punnett square for Rr x Rr
genotype ratio __25% RR, 50% Rr, 25% rr__
phenotype ratio _75% Round, 25% Wrinkled___
5. How much of your genetic information comes from your mother? __50%____ father? ___50%___
6. A recessive trait can only be visible when it is (Homozygous or Heterozygous) for a specific trait.
7. 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.
8. 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