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
Introduction
In the world of genetics, dominant and recessive traits play a crucial role in determining the characteristics of an organism. A dominant trait is one that will be expressed if an individual has one copy of the dominant allele, while a recessive trait is one that will only be expressed if an individual has two copies of the recessive allele. In this article, we will explore the concept of dominant and recessive traits in a specific species of frogs, where black spots are a dominant trait and their absence is a recessive trait.
Dominant and Recessive Traits
In genetics, traits are determined by alleles, which are different forms of a gene. An allele can be either dominant or recessive. A dominant allele will always be expressed if an individual has one copy of the dominant allele, while a recessive allele will only be expressed if an individual has two copies of the recessive allele.
The Genetics of Black Spots in Frogs
In the species of frogs we are discussing, black spots are a dominant trait, and their absence is a recessive trait. This means that if an individual frog has one copy of the dominant allele (B) and one copy of the recessive allele (b), it will still express the dominant trait and have black spots. However, if an individual frog has two copies of the recessive allele (bb), it will not express the dominant trait and will not have black spots.
Punnett Squares and Genotype
To understand the genotypes of the frogs in the population, we can use Punnett squares. A Punnett square is a diagram that shows the possible genotypes of offspring from two parents. In this case, we can use a Punnett square to determine the genotypes of the frogs in the population.
Punnett Square for Dominant and Recessive Traits
Here is a Punnett square for the dominant and recessive traits in the frogs:
| B | b | |
|---|---|---|
| B | BB | Bb |
| b | bB | bb |
In this Punnett square, the top row represents the possible genotypes of the parents, and the left column represents the possible genotypes of the offspring. The squares in the middle represent the possible genotypes of the offspring.
Genotype and Phenotype
The genotype of an individual is its genetic makeup, while the phenotype is the physical expression of the genotype. In this case, the genotype of an individual frog can be either BB, Bb, or bb, and the phenotype can be either black spots (B) or no black spots (b).
Population of Frogs
Let's say we have a population of frogs with the following genotypes:
- 50 are homozygous for the dominant trait (BB)
- 34 are heterozygous dominant (Bb)
- 16 show the recessive trait (bb)
Calculating the Genotype Frequencies
To calculate the genotype frequencies, we can use the following formula:
Genotype frequency = (Number of individuals with genotype) / (Total number of individuals)
Using this formula, we can calculate the genotype frequencies as follows:
- BB: 50 / 100 = 0.5
- Bb: 34 / 100 = 0.34
- bb: 16 / 100 = 0.16
Calculating the Allele Frequencies
To calculate the allele frequencies, we can use the following formula:
Allele frequency = (Number of copies of allele) / (2 x Total number of individuals)
Using this formula, we can calculate the allele frequencies as follows:
- B: (50 x 2) + (34 x 1) = 134 / 200 = 0.67
- b: (16 x 2) = 32 / 200 = 0.16
Conclusion
In conclusion, the concept of dominant and recessive traits is crucial in understanding the characteristics of an organism. In this article, we explored the concept of dominant and recessive traits in a specific species of frogs, where black spots are a dominant trait and their absence is a recessive trait. We used Punnett squares and genotype frequencies to understand the genotypes of the frogs in the population and calculated the allele frequencies to determine the frequency of the dominant and recessive alleles.
Understanding the Importance of Dominant and Recessive Traits
Dominant and recessive traits play a crucial role in determining the characteristics of an organism. Understanding the concept of dominant and recessive traits is essential in genetics and has many practical applications in fields such as agriculture, medicine, and conservation.
Applications of Dominant and Recessive Traits
The concept of dominant and recessive traits has many practical applications in fields such as:
- Agriculture: Understanding the concept of dominant and recessive traits is essential in plant breeding, where farmers can select for desirable traits such as disease resistance or high yield.
- Medicine: Understanding the concept of dominant and recessive traits is essential in genetic counseling, where healthcare professionals can advise patients on the likelihood of inheriting a particular trait.
- Conservation: Understanding the concept of dominant and recessive traits is essential in conservation biology, where scientists can study the genetic diversity of endangered species.
Conclusion
Q: What is the difference between a dominant and recessive trait?
A: A dominant trait is one that will be expressed if an individual has one copy of the dominant allele, while a recessive trait is one that will only be expressed if an individual has two copies of the recessive allele.
Q: How do Punnett squares work?
A: A Punnett square is a diagram that shows the possible genotypes of offspring from two parents. It is used to predict the probability of different genotypes and phenotypes in offspring.
Q: What is the genotype of an individual?
A: The genotype of an individual is its genetic makeup, which can be represented by a combination of letters (e.g. BB, Bb, or bb).
Q: What is the phenotype of an individual?
A: The phenotype of an individual is the physical expression of its genotype, which can be represented by a trait (e.g. black spots or no black spots).
Q: How do you calculate the genotype frequencies?
A: To calculate the genotype frequencies, you can use the following formula:
Genotype frequency = (Number of individuals with genotype) / (Total number of individuals)
Q: How do you calculate the allele frequencies?
A: To calculate the allele frequencies, you can use the following formula:
Allele frequency = (Number of copies of allele) / (2 x Total number of individuals)
Q: What is the difference between a homozygous and heterozygous individual?
A: A homozygous individual has two copies of the same allele (e.g. BB or bb), while a heterozygous individual has one copy of each allele (e.g. Bb).
Q: How do you determine the genotype of an individual?
A: To determine the genotype of an individual, you can use a Punnett square or other genetic tools to predict the possible genotypes and phenotypes.
Q: What is the importance of understanding dominant and recessive traits?
A: Understanding dominant and recessive traits is essential in genetics and has many practical applications in fields such as agriculture, medicine, and conservation.
Q: Can you give an example of a dominant and recessive trait in a real-world scenario?
A: Yes, an example of a dominant and recessive trait is the trait for eye color in humans. The dominant allele for brown eyes (B) is dominant over the recessive allele for blue eyes (b). If an individual has one copy of the dominant allele (B) and one copy of the recessive allele (b), they will have brown eyes.
Q: How do you predict the probability of a dominant and recessive trait in offspring?
A: To predict the probability of a dominant and recessive trait in offspring, you can use a Punnett square or other genetic tools to calculate the probability of different genotypes and phenotypes.
Q: Can you explain the concept of incomplete dominance?
A: Yes, incomplete dominance is a phenomenon where the dominant allele does not completely mask the effect of the recessive allele. This results in a blend of the two alleles, rather than a complete dominance of one over the other.
Q: Can you explain the concept of codominance?
A: Yes, codominance is a phenomenon where both alleles have an equal effect on the phenotype, resulting in a combination of the two alleles. This is different from incomplete dominance, where the dominant allele still has a greater effect on the phenotype.