Final answer:
The genotype is the genetic makeup of an organism, while the phenotype is the observable physical expression of the genotype. Despite having the same genotype, organisms can exhibit different phenotypes due to environmental influences. Mendel's experiments demonstrated how genotypes determine phenotypes and how different genotypes can lead to the same phenotype.
Step-by-step explanation:
The biological approach to genetics distinguishes between two key concepts: genotype and phenotype. The genotype represents an organism's genetic makeup, including all the alleles inherited from the parents. It is essentially a genetic blueprint that determines what traits have the potential to be expressed. For example, in pea plants, the genotype for seed color can be represented by letters such as YY (homozygous dominant), Yy (heterozygous), or yy (homozygous recessive).
On the other hand, the phenotype is the observable expression of the genotype; it's the physical manifestation of an organism's traits, such as yellow or green seed color in peas. The phenotype is influenced by the genotype and can also be affected by environmental factors. Even if two organisms have the same genotype, their phenotypes can differ due to variations in their environments affecting gene expression. For instance, two plants with the same genotype for height may grow to different heights if one receives more sunlight or nutrients.
Mendelian genetics, demonstrated by Gregor Mendel's hybridization experiments, revealed how certain traits are inherited and expressed. It's important to note that a dominant allele in a heterozygous pair (such as Yy) can mask the expression of a recessive allele, explaining how different genotypes can result in the same phenotype, whereas the recessive trait only appears in the homozygous recessive genotype (such as yy).