Which description is an example of a phenotype?

• A. A trait is inherited according to Mendel’s law of segregation.
• B. A DNA molecule contains a specific nucleotide sequence in a gene.
• C. A pea plant has the genotype $A_1{A}_2$.
• D. A pea plant has purple flowers.

Answer: (D)

Verified step by step guidance

1. Understand the difference between genotype and phenotype: Genotype refers to the genetic makeup of an organism (the specific alleles it carries), while phenotype refers to the observable physical or biochemical characteristics resulting from the genotype and environment.
2. Identify examples of genotype in the options: For example, a DNA molecule's nucleotide sequence or a plant's specific alleles (like $\backslash (\backslash text\{A\}\backslash )\_1\backslash (\backslash text\{A\}\backslash )\_2$) represent genotype because they describe the genetic information.
3. Identify examples of phenotype in the options: Phenotype is about observable traits, such as flower color, height, or seed shape, which can be seen or measured.
4. Evaluate each option to determine if it describes a phenotype: The statement 'A pea plant has purple flowers' describes an observable trait, which is a phenotype.
5. Conclude that the correct example of a phenotype is the observable characteristic, such as flower color, rather than genetic information or laws.