Select The Correct Answer.In A Particular Species Of Frogs, Black Spots Are A Dominant Trait And Their Absence Is A Recessive Trait. In A Population Of Frogs, 50 Are Homozygous For The Dominant Trait, 34 Are Heterozygous Dominant, And 16 Show The

Understanding the Genetics of Frog Traits: A Dominant and Recessive Trait Analysis

In the world of genetics, traits are often determined by the interaction of dominant and recessive alleles. A dominant allele will always be expressed if an individual has one copy of the allele, while a recessive allele will only be expressed if an individual has two copies of the allele. In this article, we will explore the concept of dominant and recessive traits using the example of a particular species of frogs, where black spots are a dominant trait and their absence is a recessive trait.

The Genetics of Dominant and Recessive Traits

To understand the genetics of dominant and recessive traits, let's first define the terms. A dominant allele is an allele that will always be expressed if an individual has one copy of the allele. A recessive allele, on the other hand, will only be expressed if an individual has two copies of the allele. In the case of the frogs, the black spots are a dominant trait, meaning that if an individual has one copy of the dominant allele, they will express the black spots. The absence of black spots, on the other hand, is a recessive trait, meaning that an individual must have two copies of the recessive allele to express the trait.

The Punnett Square: A Tool for Predicting Genotype and Phenotype

One of the most powerful tools in genetics is the Punnett square. A Punnett square is a diagram that shows the possible genotypes and phenotypes of offspring from a cross between two parents. To create a Punnett square, we need to know the genotype of the parents. In this case, let's assume that the 50 homozygous dominant frogs are the parents. Since they are homozygous dominant, their genotype is BB, where B represents the dominant allele.

Calculating the Genotype and Phenotype of Offspring

To calculate the genotype and phenotype of offspring, we need to create a Punnett square. The Punnett square will show the possible genotypes and phenotypes of offspring from a cross between two parents. In this case, the Punnett square will show the possible genotypes and phenotypes of offspring from a cross between two homozygous dominant frogs.

  | B | b
------------------
B | BB | Bb
b | Bb | bb

In the Punnett square above, the top row represents the genotype of the first parent, and the left column represents the genotype of the second parent. The squares in the grid represent the possible genotypes and phenotypes of offspring. The genotype BB represents the homozygous dominant genotype, while the genotype Bb represents the heterozygous genotype. The genotype bb represents the homozygous recessive genotype.

Interpreting the Punnett Square

To interpret the Punnett square, we need to look at the possible genotypes and phenotypes of offspring. In this case, the Punnett square shows that 25% of offspring will be homozygous dominant (BB), 50% will be heterozygous (Bb), and 25% will be homozygous recessive (bb).

The Relationship Between Genotype and Phenotype

In the case of the frogs, the genotype BB represents the homozygous dominant genotype, which means that the individual will express the black spots. The genotype Bb represents the heterozygous genotype, which means that the individual will also express the black spots. The genotype bb represents the homozygous recessive genotype, which means that the individual will not express the black spots.

The Frequency of Dominant and Recessive Traits

In the population of frogs, 50 are homozygous for the dominant trait, 34 are heterozygous dominant, and 16 show the recessive trait. To calculate the frequency of dominant and recessive traits, we need to divide the number of individuals with each genotype by the total number of individuals in the population.

Frequency of dominant trait = (Number of homozygous dominant individuals + Number of heterozygous dominant individuals) / Total number of individuals
Frequency of dominant trait = (50 + 34) / 100
Frequency of dominant trait = 84 / 100
Frequency of dominant trait = 0.84

Frequency of recessive trait = Number of homozygous recessive individuals / Total number of individuals
Frequency of recessive trait = 16 / 100
Frequency of recessive trait = 0.16

Conclusion

In conclusion, the genetics of dominant and recessive traits is a complex and fascinating field of study. By using the Punnett square and calculating the frequency of dominant and recessive traits, we can gain a deeper understanding of the genetics of frog traits. The example of the frogs, where black spots are a dominant trait and their absence is a recessive trait, illustrates the concept of dominant and recessive traits and how they are expressed in a population.

References

• Campbell, N. A., & Reece, J. B. (2008). Biology. 7th ed. San Francisco: Pearson Education.
• Griffiths, A. J. F., Wessler, S. R., Lewontin, R. C., & Gelbart, W. M. (2000). An introduction to genetic analysis. 7th ed. New York: W.H. Freeman and Company.
• Hartl, D. L., & Jones, E. W. (2005). Genetics: Analysis of Genes and Genomes. 6th ed. San Francisco: Pearson Education.
  Frequently Asked Questions: Dominant and Recessive Traits

In the previous article, we explored the concept of dominant and recessive traits using the example of a particular species of frogs, where black spots are a dominant trait and their absence is a recessive trait. In this article, we will answer some frequently asked questions about dominant and recessive traits.

Q: What is the difference between a dominant and a recessive trait?

A: A dominant trait is a trait that will always be expressed if an individual has one copy of the dominant allele. A recessive trait, on the other hand, will only be expressed if an individual has two copies of the recessive allele.

Q: How do dominant and recessive traits interact with each other?

A: When a dominant and a recessive allele are present in an individual, the dominant allele will always be expressed. This is because the dominant allele is "dominant" over the recessive allele.

Q: What is the Punnett square, and how is it used to predict genotype and phenotype?

A: The Punnett square is a diagram that shows the possible genotypes and phenotypes of offspring from a cross between two parents. It is used to predict the genotype and phenotype of offspring by showing the possible combinations of alleles that can be inherited from the parents.

Q: How do you calculate the frequency of dominant and recessive traits in a population?

A: To calculate the frequency of dominant and recessive traits, you need to divide the number of individuals with each genotype by the total number of individuals in the population.

Q: What is the difference between a homozygous dominant and a heterozygous individual?

A: A homozygous dominant individual has two copies of the dominant allele, while a heterozygous individual has one copy of the dominant allele and one copy of the recessive allele.

Q: Can a recessive trait be expressed if an individual has only one copy of the recessive allele?

A: No, a recessive trait will only be expressed if an individual has two copies of the recessive allele.

Q: How do you determine the genotype of an individual based on their phenotype?

A: To determine the genotype of an individual based on their phenotype, you need to know the genotype of the parents and the possible genotypes and phenotypes of offspring. You can then use the Punnett square to predict the genotype and phenotype of the individual.

Q: Can a dominant trait be expressed if an individual has only one copy of the dominant allele?

A: Yes, a dominant trait will always be expressed if an individual has one copy of the dominant allele.

Q: What is the significance of dominant and recessive traits in genetics?

A: Dominant and recessive traits are significant in genetics because they help us understand how traits are inherited and expressed in individuals and populations.

Q: Can you give an example of a dominant and recessive trait in humans?

A: Yes, a common example of a dominant and recessive trait in humans is the trait for freckles. The presence of freckles is a dominant trait, while the absence of freckles is a recessive trait.

Q: How do you predict the genotype and phenotype of offspring from a cross between two parents?

A: To predict the genotype and phenotype of offspring from a cross between two parents, you need to know the genotype of the parents and use the Punnett square to show the possible genotypes and phenotypes of offspring.

Q: Can a recessive trait be expressed if an individual has a combination of dominant and recessive alleles?

A: No, a recessive trait will only be expressed if an individual has two copies of the recessive allele.

Q: What is the difference between a genotype and a phenotype?

A: A genotype is the genetic makeup of an individual, while a phenotype is the physical expression of the genotype.

Q: Can you give an example of a dominant and recessive trait in plants?

A: Yes, a common example of a dominant and recessive trait in plants is the trait for flower color. The presence of red flowers is a dominant trait, while the presence of white flowers is a recessive trait.

Q: How do you determine the genotype of an individual based on their family history?

A: To determine the genotype of an individual based on their family history, you need to know the genotype of the parents and grandparents and use the Punnett square to predict the genotype and phenotype of the individual.

Q: Can a dominant trait be expressed if an individual has a combination of dominant and recessive alleles?

A: Yes, a dominant trait will always be expressed if an individual has one copy of the dominant allele, regardless of the presence of recessive alleles.