Black skin color is dominant to pink skin color in pigs. Two heterozygous black pigs are crossed.
What is the probability that the first and second offspring will have black skin?

Verified step by step guidance

1. Step 1: Identify the genetic makeup of the parents. Since both pigs are heterozygous for black skin color, their genotype is Bb, where 'B' represents the dominant allele for black skin and 'b' represents the recessive allele for pink skin.
2. Step 2: Set up a Punnett square to determine the possible genotypes of the offspring. Place one parent's alleles (B and b) along the top of the square and the other parent's alleles (B and b) along the side.
3. Step 3: Fill in the Punnett square by combining the alleles from the top and side. The resulting genotypes will be: BB (homozygous dominant), Bb (heterozygous), Bb (heterozygous), and bb (homozygous recessive).
4. Step 4: Determine the phenotypic ratio from the Punnett square. Since 'B' is dominant, both BB and Bb will result in black skin, while bb will result in pink skin. The phenotypic ratio is 3:1 (3 black : 1 pink).
5. Step 5: Calculate the probability of both the first and second offspring having black skin. Since the probability of one offspring having black skin is 3/4, multiply this probability by itself for two independent events: \( \frac{3}{4} \times \frac{3}{4} \).

Key Concepts

Dominant and Recessive Traits

In genetics, traits are often categorized as dominant or recessive. A dominant trait, such as black skin color in pigs, will express itself in the phenotype even if only one allele is present. In contrast, a recessive trait, like pink skin color, requires two copies of the recessive allele to be expressed. Understanding this distinction is crucial for predicting offspring traits.

Punnett Square

A Punnett square is a diagram used to predict the genetic makeup of offspring from a particular cross. By organizing the alleles of the parents, it allows for the visualization of possible combinations in the offspring. In this case, crossing two heterozygous black pigs (Bb x Bb) will help determine the probabilities of black and pink skin color in their offspring.

Probability in Genetics

Probability in genetics refers to the likelihood of certain traits being passed from parents to offspring. When calculating the probability of specific traits, such as the likelihood of both offspring having black skin, one must consider the outcomes from the Punnett square. For two heterozygous parents, the probability of each offspring being black can be calculated and then combined for multiple offspring.