10.E: Patterns of Inheritance (Exercises)
10.1: Mendel’s Experiments
Multiple Choice
Imagine that you are performing a cross involving seed color in garden pea plants. What traits would you expect to observe in the F 1 offspring if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green.
A. only yellow-green seeds
B. only yellow seeds
C. 1:1 yellow seeds:green seeds
D. 1:3 green seeds:yellow seeds
- Answer
-
B
Imagine that you are performing a cross involving seed texture in garden pea plants. You cross true-breeding round and wrinkled parents to obtain F 1 offspring. Which of the following experimental results in terms of numbers of plants are closest to what you expect in the F 2 progeny?
A. 810 round seeds
B. 810 wrinkled seeds
C. 405:395 round seeds:wrinkled seeds
D. 610:190 round seeds:wrinkled seeds
- Answer
-
D
Free Response
Describe one of the reasons that made the garden pea an excellent choice of model system for studying inheritance.
- Answer
-
The garden pea has flowers that close tightly during self-pollination. This helps to prevent accidental or unintentional fertilizations that could have diminished the accuracy of Mendel’s data.
10.2: Laws of Inheritance
Multiple Choice
The observable traits expressed by an organism are described as its ________.
A. phenotype
B. genotype
C. alleles
D. zygote
- Answer
-
A
A recessive trait will be observed in individuals that are ________ for that trait.
A. heterozygous
B. homozygous or heterozygous
C. homozygousdiploid
- Answer
-
C
What are the types of gametes that can be produced by an individual with the genotype AaBb ?
A.
Aa
,
Bb
B.
AA
,
aa
,
BB
,
bb
C.
AB
,
Ab
,
aB
,
ab
D.
AB
,
ab
- Answer
-
C
What is the reason for doing a test cross?
A. to identify heterozygous individuals with the dominant phenotype
B. to determine which allele is dominant and which is recessive
C. to identify homozygous recessive individuals in the F
2
D. to determine if two genes assort independently
- Answer
-
A
Free Response
Use a Punnett square to predict the offspring in a cross between a dwarf pea plant (homozygous recessive) and a tall pea plant (heterozygous). What is the phenotypic ratio of the offspring?
- Answer
-
The Punnett square would be 2 × 2 and will have T and T along the top and T and t along the left side. Clockwise from the top left, the genotypes listed within the boxes will be Tt , Tt , tt , and tt . The phenotypic ratio will be 1 tall:1 dwarf.
Use a Punnett square to predict the offspring in a cross between a tall pea plant (heterozygous) and a tall pea plant (heterozygous). What is the genotypic ratio of the offspring?
- Answer
-
The Punnett square will be 2 × 2 and will have T and t along the top and T and t along the left side. Clockwise from the top left, the genotypes listed within the boxes will be TT , Tt , Tt , and tt . The genotypic ratio will be 1 TT :2 Tt :1 tt .
10.3: Extensions of the Laws of Inheritance
Multiple Choice
If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of?
A. dominance
B. codominance
C. multiple alleles
D. incomplete dominance
- Answer
-
D
The ABO blood groups in humans are expressed as the I A , I B , and i alleles. The I A allele encodes the A blood group antigen, I B encodes B, and i encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent ( I A i ) and a heterozygous blood type B parent ( I B i ) mate, one quarter of their offspring are expected to have the AB blood type ( I A I B ) in which both antigens are expressed equally. Therefore, ABO blood groups are an example of:
A. multiple alleles and incomplete dominance
B. codominance and incomplete dominance
C. incomplete dominance only
D. multiple alleles and codominance
- Answer
-
D
In a cross between a homozygous red-eyed female fruit fly and a white-eyed male fruit fly, what is the expected outcome?
A. all white-eyed male offspring
B. all white-eyed female offspring
C. all red-eyed offspring
D. half white-eyed make offspring
- Answer
-
C
When a population has a gene with four alleles circulating, how many possible genotypes are there?
A. 3
B. 6
C. 10
D. 16
- Answer
-
C
Free Response
Can a male be a carrier of red-green color blindness?
- Answer
-
No, males can only express color blindness and cannot carry it because an individual needs two X chromosomes to be a carrier.
Could an individual with blood type O (genotype ii ) be a legitimate child of parents in which one parent had blood type A and the other parent had blood type B?
- Answer
-
Yes this child could have come from these parents. The child would have inherited an i allele from each parent and for this to happen the type A parent had to have genotype I A i and the type b parent had to have genotype I B i .
Contributors and Attributions
Remixed and/or curated from the following works:
Fowler, S., Roush, R., & Wise, J. (2013). 8.E Patterns of Inheritance (Exercises) . In Concepts of Biology . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/concepts-biology/pages/1-introduction ).