Which of the following can be concluded from Gregor Mendel’s experiments with pea plants?
for a given trait, two heterozygous parents produce offspring with three possible phenotypes
two recessive alleles are necessary for a recessive phenotype
allelic combinations for different genes may differ between parents and their offspring
offspring inherit two alleles per gene from each parent
The Correct Answer and Explanation is :
The correct answer is: two recessive alleles are necessary for a recessive phenotype.
Explanation:
Gregor Mendel’s experiments with pea plants formed the foundation of modern genetics. His research focused on inheritance patterns of specific traits, such as flower color, seed shape, and pod color, and he used the concepts of dominant and recessive alleles to explain how traits were passed from parents to offspring.
- Two recessive alleles are necessary for a recessive phenotype:
This conclusion comes from Mendel’s observation that recessive traits are expressed only when both alleles for a trait are recessive. For example, in Mendel’s pea plant experiments, the allele for green seeds (recessive) only resulted in green seeds when the plant inherited two recessive alleles (one from each parent). If the plant had a dominant allele (e.g., for yellow seeds), the dominant trait would be expressed, masking the recessive trait. Thus, a recessive phenotype appears only when the individual has two copies of the recessive allele. - For a given trait, two heterozygous parents produce offspring with three possible phenotypes:
This is partially true but requires clarification. When two heterozygous parents are crossed (e.g., both having one dominant and one recessive allele), their offspring may indeed show a combination of three different phenotypes. For a single trait, such as seed color in pea plants, the heterozygous cross (Yy x Yy) produces offspring in a 1:2:1 genotype ratio (1 YY, 2 Yy, 1 yy), which results in two phenotypes—dominant and recessive. Thus, Mendel’s experiments show that offspring inherit traits in a predictable way, but the number of phenotypes can vary. - Allelic combinations for different genes may differ between parents and their offspring:
Mendel’s principle of independent assortment suggests that alleles for different traits assort independently of one another, meaning the combination of alleles for different genes in offspring can be different from the parental combinations. - Offspring inherit two alleles per gene from each parent:
Mendel demonstrated this through his monohybrid crosses. Each parent contributes one allele to the offspring, so offspring inherit one allele from each parent, resulting in two alleles per gene, one from each parent. This is known as the Law of Segregation.
In conclusion, the key finding from Mendel’s experiments is that for a recessive phenotype to appear, an individual must inherit two recessive alleles, one from each parent.