Q: Based on the first image, calculate the recombination frequency between the genes for flower color and pollen shape using the observed recombinant offspring (purple round and red long). Use the formula $$\text{Recombination Frequency} = \frac{\text{Number of Recombinants}}{\text{Total Offspring}} \times 100\%.$$

$$\frac{21 + 21}{381} \times 100\% = 11\%$$

Question 1

In the first image, the observed offspring from a dihybrid cross do not match the predicted 9:3:3:1 ratio. Which genetic phenomenon best explains why the observed numbers of purple long and red round phenotypes are higher than predicted, while purple round and red long are lower?

Accepted Answer

Some of the alleles are linked, reducing independent assortment.

Question 2

Based on the first image, calculate the recombination frequency between the genes for flower color and pollen shape using the observed recombinant offspring (purple round and red long). Use the formula $$	ext{Recombination Frequency} = \frac{	ext{Number of Recombinants}}{	ext{Total Offspring}} 	imes 100\%.$$

Accepted Answer

$$\frac{21 + 21}{381} 	imes 100\% = 11\%$$

Question 3

Refer to the second image (pedigree). What is the most likely mode of inheritance for the trait shown in black?

Accepted Answer

Autosomal recessive

Question 4

In the second image, if individuals II-2 and II-3 have a child, what is the probability that their child will express the trait (black symbol), assuming the trait is autosomal recessive?

Accepted Answer

$$\frac{1}{4}$$

Question 5

In the third image, what is the genotype of Mary regarding the widow's peak trait, given that widow's peak is dominant (W) and she has the trait?

Accepted Answer

Ww

Question 6

In the third image, Janice does not have a widow's peak. What is her genotype?

Accepted Answer

ww

Question 7

If Joseph (third image) is heterozygous for widow's peak and Alicia is homozygous recessive, what is the probability that their child will have a widow's peak?

Accepted Answer

$$\frac{1}{2}$$

Question 8

A couple, both heterozygous for a rare autosomal recessive disease, have one affected child. What is the probability that their next child will also be affected?

Accepted Answer

$$\frac{1}{4}$$

Question 9

Which of the following tests would NOT be useful for detecting a genetic disorder in an unborn child?

Accepted Answer

Pedigree analysis

Question 10

A test cross is used to determine the genotype of an individual expressing a dominant trait. Which cross would you perform?

Accepted Answer

Cross with a homozygous recessive individual

Question 11

A purebred purple-flowered pea plant is crossed with a purebred white-flowered pea plant. All offspring have purple flowers. What does this indicate about the purple allele?

Accepted Answer

It is dominant to the white allele.

Question 12

If a trait is controlled by two or more genes and shows a continuous range of phenotypes, what is this pattern of inheritance called?

Accepted Answer

Polygenic inheritance

Question 13

A BbCc × bbcc cross produces offspring in a 5:5:1:1 phenotypic ratio. What does this suggest about the genes involved?

Accepted Answer

They are linked and do not assort independently.

Question 14

Which of the following best describes the relationship between the LM and LN alleles in an individual with the blood group genotype LMLN (MN phenotype)?

Accepted Answer

Codominance

Question 15

A researcher finds that the degree of social behavior in dogs toward humans is correlated with a chemical modification of a chromosome, not with specific alleles. What is this an example of?

Accepted Answer

Epigenetics

Patterns of Inheritance – General Biology Final Exam Review Guidance

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