Gregor Mendel’s cross-breeding experiments with pea plants in the 19th century laid the foundation for modern genetics. His laws of inheritance revealed patterns of genetic transmission, contributing significantly to the understanding of heredity.
If two pea plants having round and green seeds (RRGg) are crossed, identify the percentage of the following with respect to the F1 generation: (a) gametes having both the round and yellow seed traits (b) offspring having the same genotype as the parents (c) offspring having the same phenotype as the parents
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To determine the gametes produced by the pea plants with the genotype RRGg, we need to consider the possible combinations of alleles.
The genotype RRGg can produce four types of gametes:
• RG (round and green)
• Rg (round and yellow)
• rG (wrinkled and green)
• rg (wrinkled and yellow)
Now, let’s consider the cross between two pea plants (RRGg × RRGg):
(a) Gametes having both the round and yellow seed traits (Rg): 25%
(b) Offspring having the same genotype as the parents (RRGg): 50%
(c) Offspring having the same phenotype as the parents (round and green): 75%
Explanation:
(a) The RRGg plants can produce four types of gametes in equal proportions (25% each). One of these gametes is Rg, which represents 25% of the total possible gametes.
(b) In the F1 generation, the possible genotypes are RR, Rg, RG, and gg. The RRGg genotype is 50% of the total possible genotypes.
(c) The phenotype is determined by the physical expression of the traits. In this case, the round and green phenotype is expressed by the genotypes RR and RRGg. The sum of these genotypes is 75% of the total possible phenotypes in the F1 generation.