Question

In garden peas, purple flower color is dominant to white flower color. In a population of 500 pea plants, 180 of them are white and 320 of them are purple. How many white flower alleles are present in this population?
A) 80
B) 210
C) 240
D) 310
D) 120

Answer 1

An allele is 1 of the 2 or more versions or types of a particular gene. In an organism, 2 alleles for a particular gene are expressed. They further intermingle to give physical characteristics. Mendel’s experiments of hybridization establish the difference between genotype and phenotype.

Complete answer:
Garden pea plants with purple flowers are 320, whereas garden pea plants having white color flowers are 180. Thus, the recessive allele is
$q \times q = 180 = 0.18$
Therefore, $q = 0.42$
Now, as we know that $p + q = 1$
So, p is equal to $0.58$.
This suggests that the purple allele is dominant on the white, that’s why the heterozygous plants will have white alleles as well.
Hence the white alleles would be equal to $q + \dfrac{1}{2}\left( {2pq} \right){\text{ }} = 0.42 + \dfrac{1}{2}\left( {2 \times 0.42 \times 0.58} \right){\text{ }} = 0.6216$. Now as we already know that there are 500 flowers in total, so$$$$Therefore, 320 white flower alleles are present in the population.

Additional information: The 7 features that Mendel evaluated in the garden pea plants were each one expressed as 1 of 2 types, or traits. Mendel inferred from his outcomes that each individual ensured two separate copies of the characteristic that are approved independently to the offspring. We now can call those two copies as genes, which are there on chromosomes. The reason that we have 2 copies of each gene is that we receive one copy from each parent of the 2. We are aware that during the process of meiosis the chromosomes are divided out in haploid gametes. This segregation, or division, of the homologous chromosomes also tell us that only 1 of the 2 copies of the gene is moved in a gamete

Note: In actual fact, we inherit the chromosomes, and the copies of genes, both of them are located on those paired chromosomes. The offspring or progenies are created when this gamete gets together with 1 from another parent and the 2 copies of each chromosome and gene are brought back.