Which of the statements can be concluded from Gregor Mendel’s experiments with pea plants? (more than one correct answer)
a. Parents with dominant phenotypes always have offspring with dominant phenotypes.
b. Two recessive alleles are necessary for a recessive phenotype.
c. Allelic combinations for different genes may differ between parents and their offspring.
d. Offspring inherit two alleles per gene from each parent.
The correct answer and explanation is:
The correct answers are:
b. Two recessive alleles are necessary for a recessive phenotype.
c. Allelic combinations for different genes may differ between parents and their offspring.
d. Offspring inherit two alleles per gene from each parent.
Explanation:
Gregor Mendel’s experiments with pea plants laid the foundation for the understanding of genetic inheritance. Here’s a breakdown of the conclusions that can be drawn from his work:
- Two recessive alleles are necessary for a recessive phenotype (b):
Mendel’s work showed that for a recessive trait to be expressed in an organism, both alleles for that gene must be recessive. This means an organism must inherit one recessive allele from each parent. For example, in the case of flower color in peas, a plant with the genotype “aa” (where “a” is the recessive allele) would exhibit the recessive phenotype. If a dominant allele (“A”) was present, the dominant phenotype would be expressed instead. - Allelic combinations for different genes may differ between parents and their offspring (c):
Mendel’s experiments also demonstrated that the alleles for different traits assort independently of each other during gamete formation. This is known as the law of independent assortment. Therefore, the combination of alleles a parent passes on for one gene does not necessarily affect the combination for other genes. For example, the alleles for seed shape (round or wrinkled) can assort independently from those for seed color (yellow or green), resulting in different combinations in the offspring. - Offspring inherit two alleles per gene from each parent (d):
According to Mendel’s law of segregation, each organism inherits two alleles for each gene—one from each parent. These alleles can be the same (homozygous) or different (heterozygous). When the organism reproduces, it passes only one of the alleles to its offspring, ensuring genetic diversity in the next generation.
Incorrect statement (a):
Parents with dominant phenotypes do not always have offspring with dominant phenotypes. This is because dominant alleles only require one copy to be expressed, but if a parent is heterozygous (for example, “Aa”), the offspring may inherit the recessive allele (“a”) from both parents and show the recessive phenotype.