What is meant by a phenotype ratio in a Punnett square?(1 point)
Responses
the fraction of possible offspring that contain a certain allele in their genes
the fraction of possible offspring that can be observed to have a trait
the number of alleles in possible offspring
the number of genes that are possible in offspring
The correct answer is: the fraction of possible offspring that can be observed to have a trait.
The correct response is:
the fraction of possible offspring that can be observed to have a trait
The correct answer is: the fraction of possible offspring that can be observed to have a trait.
In a Punnett square, the phenotype ratio represents the proportion or fraction of potential offspring that will exhibit a particular trait. This ratio is determined by analyzing the combinations of alleles that are inherited from the parents. Each square within the Punnett square represents a possible combination of alleles, and by examining these combinations, we can determine the likelihood of certain traits being expressed in the offspring.
To obtain the phenotype ratio in a Punnett square, you need to:
1. Identify the alleles present in each parent's genotype.
2. Write out the parent's genotypes and create the Punnett square by crossing their alleles.
3. Determine the allele combinations in each square of the Punnett square.
4. Assign the corresponding phenotype or observable trait to each allele combination.
5. Count the number of squares that exhibit the desired trait and divide it by the total number of squares to get the phenotype ratio.
By following these steps, you can calculate the phenotype ratio and understand the likelihood of certain traits appearing in the offspring.
What is the definition of epistasis?(1 point)
Responses
when one trait is determined by multiple genes
when one trait is determined by multiple genes
when a dominant allele for a specific trait is not completely expressed over the recessive allele
when a dominant allele for a specific trait is not completely expressed over the recessive allele
when the allele of one gene interferes with the expression of another gene
when the allele of one gene interferes with the expression of another gene
when one gene affects multiple phenotypes
The correct answer is: when the allele of one gene interferes with the expression of another gene.
Epistasis refers to the phenomenon where the allele of one gene masks or modifies the expression of another gene. In other words, the presence or absence of one gene affects the expression of another gene. This can result in the alteration or suppression of certain traits or phenotypes. Epistasis can occur in cases where one gene is acting as a suppressor or blocker of the expression of another gene.
Which is an example of codominance?(1 point)
Responses
black and brown spotted coat color in horses
seed shape in pea plants
tall and short plant heights
black and yellow coat color in Labrador retrievers
Consider that a plant with genotype RR has red flowers and a plant with genotype WW has white flowers. This plant species expresses incomplete dominance for flower color when the plant is heterozygous.
The offspring of a cross between an RR plant and a WW plant would be
(1 point)
Responses
red and pink.
all white.
pink and white.
all pink.
A genetic disease is found in a family that affects the immune system, lungs, heart, and kidneys. A DNA analysis of several affected and unaffected family members determines that the disease is caused by a mutation in a single gene. What type of inheritance pattern is shown in this disease?(1 point)
Responses
polygenic trait
codominance
incomplete dominance
pleiotropy
The correct answer is: pleiotropy.
Pleiotropy refers to a phenomenon in which a single gene mutation affects multiple phenotypic traits. In this case, the genetic disease is affecting the immune system, lungs, heart, and kidneys, indicating that the mutation in a single gene is causing a wide range of symptoms and complications. This is an example of pleiotropy, where a mutation in one gene has multiple effects on various parts or systems of the body.
If a homozygous white horse CWCW and a homozygous black horse CBCB are bred together, what is the likelihood that their offspring will be roan with both colors represented in their hair if this gene follows a codominant inheritance pattern?(1 point)
Responses
100%
50%
0%
25%