Answer:
The values that most closely represent the expected number of Janice blonde-haired offspring is 252 individuals, option C.
Explanation:
<u>Available data</u>:
- Two diallelic genes acting in a recessive epistatic manner to express hair color
- Allele A is dominant over the allele a
- Allele B is dominant over the allele b
- A_B_ Cookie monster blue
- aaB_ Elmo red
- __bb Janice blonde
When talking about epistasis, we are referring to an interruption. These are interactions between genes located in different loci in the same chromosome. An epistatic gene can alter, influence, or suppress the expression of a hypostatic gene. When the epistatic gene is recessive, the interaction is known as <u>recessive epistasis</u>.
Observing the altered phenotype proportions of the offspring can reveal which interaction is operating in the trait determination.
In recessive epistasis, the proportion is 9:3:4.
Cross: Between two doubly-heterozygous
Parentals) AaBb x AaBb
Phenotype) Cookie-monster blue-haired individuals
Gametes) AB, Ab, aB, ab
AB, Ab, aB, ab
Punnett square) AB Ab aB ab
AB AABB AABb AaBB AaBB
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
F1) 1000 individuals
9/16 individuals are expected to be Cookie-monster blue-haired, A-B-
3/16 individuals are expected to be Elmo Red, aaB-
4/16 individuals are expected to be Janice blond, A-bb + aabb
16 ------------------------------------------- 1000 individuals
4 Janice blond individuals ---------- X = 250 individuals
So, 250 individuals are expected to be Janice blonde. The observed number might vary a little bit from this value. The values that most closely represent the expected number of Janice blonde-haired offspring is c = 252 individuals
