A population of rabbits adheres to the typical inheritance pattern and the law of dominance for fur color. The allele for black fur is B, and the allele for white fur is b. If 120 rabbits are born, how many should have black fur according to the Punnett square?

To predict how many rabbits should have black fur according to the Punnett square, we first need to know the genotypes of the parent rabbits. Let's assume that we are dealing with a simple case where both parents are heterozygous for fur color, which means they both have one allele for black fur (B) and one allele for white fur (b). Their genotypes would be Bb for both.

A Punnett square can help us predict the possible genotypes of their offspring, by crossing the alleles of each parent. Here's how the Punnett square would look for two heterozygous Bb parents:

Parent 1 alleles (Bb) across the top, and Parent 2 alleles (Bb) down the side.

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

- When a B from Parent 1 combines with a B from Parent 2, the offspring is BB (homozygous dominant for black fur). - When a B from Parent 1 combines with a b from Parent 2, or vice versa, the offspring is Bb (heterozygous with black fur being dominant). - When a b from both parents combine, the offspring is bb (homozygous recessive for white fur).

From the Punnett square, we can see that there are three combinations that result in black fur (BB, Bb, Bb) and one combination that results in white fur (bb).

The ratios of the offspring genotypes will be: - 1 BB (homozygous black) - 2 Bb (heterozygous black) - 1 bb (homozygous white)

To calculate the number of black-furred rabbits, we combine the homozygous dominant (BB) and heterozygous (Bb) instances, which are 3 out of 4 possible outcomes. Since the total number of rabbits born is 120, we can calculate the expected number of black-furred rabbits as follows:

3/4 of 120 = 0.75 * 120 = 90 rabbits

So, according to the Punnett square, we would expect 90 of the 120 rabbits to have black fur.

Extra: The law of dominance states that in a heterozygous condition, the allele that is dominant completely masks the effect of the allele that is recessive. In this rabbit example, black fur (B) is dominant and white fur (b) is recessive. Therefore, only rabbits with two recessive alleles (bb) will have white fur. The other combinations (BB and Bb) will both result in black fur, even though the Bb rabbits will also carry the allele for white fur.

Understanding how alleles are inherited and expressed in an organism is part of genetics, which is a vital field of study in biology. Gregor Mendel, a 19th-century scientist, was the first to develop the laws of inheritance, using pea plants to establish the concepts of dominant and recessive traits, which are still fundamental in genetics today. Mendelian inheritance forms the basis of classical genetics and explains how traits are passed down from one generation to the next.