Final answer:
To describe his sister's physical characteristics for a blind date with Marlin, Roger would need to discuss her phenotype, the observable traits of an organism.
Step-by-step explanation:
The subject of this question is Biology.
To know facts like hair color, body type, etc., Marlin would need to know his friend Roger's sister's phenotype. Phenotype refers to the observable traits of an organism, such as physical characteristics.
Genotype, on the other hand, refers to the underlying genetic makeup of an organism, including the combination of alleles. Allele differentiation is not relevant in this context. The question presented asks about the kind of information that Roger would need to provide about his sister for a blind date with Marlin. If Marlin is interested in physical characteristics such as hair color and body type, Roger would need to describe his sister's phenotype. A phenotype consists of the observable traits of an organism, which are the result of the interaction of an organism's genotype (the underlying genetic makeup) with its environment. It's important to note that while a phenotype can give some insight into an organism's genotype, it does not reveal the specific genetic alleles that encode for the traits.