In pea plants, tall plants are dominant to dwarf plants. Two heterozygous plants are crossed. If they have 80 offspring, how many plants would be dwarf sized? How many would be tall?

20 plants would be dwarfs.

Explanation:

As you may already know, heterozygous plants have a dominant allele forming a double with a recessive allele, these alleles are represented by the letters "Aa".

The above question states that recessive alleles are only expressed if the pair of alleles of a paracteritica is formed by two recessive alleles. For this reason, as we know that dwarf plants are recessive, we know that they have the pair of alleles represented by the letters "aa".

The crossing between two heterozygous plants would result in the following offspring:

Crossing: Aa * Aa = AA, Aa, Aa, aa.

With that we can see that only 25% of the offspring would present the "aa" alleles and would be dwarf plants.

If this crossing generated 80 plants, we could conclude that 25% of these plants would be dwarfs. Then we can calculate the amount of dwarf plants, as shown below:

80 plants = 100% offspring

x plants = 25% of offspring

x = (80 * 25) / 100

X = 20 plants.

Of the 80 plants generated by crossing two heterozygous plants, 20 plants would have the "aa" alleles and would be dwarf plants.