A genetics researcher classifies several human phenotypic observations recorded during a demographic study. Match each phenotypic observation on the left with its correct variation category and genetic basis on the right.
- Gradual variation in skin melanin density across a population creating a spectrum of shadesContinuous morphological trait controlled by polygenes and modified by environmental factors
- Presence or absence of the chemical tasting perception for phenylthiocarbamide (PTC)Discontinuous physiological trait governed by a single autosomal gene pair
- Distinct classification of individuals into dermatoglyphic loop, whorl, or arch categoriesDiscontinuous morphological trait determined by genetics and uninfluenced by environment
- Production of specific A, B, or O agglutinogens on erythrocyte membranesDiscontinuous physiological trait determined by a multiple allelic system exhibiting codominance
Answer
Gradual variation in skin melanin density matches continuous polygenic morphological trait; PTC tasting perception matches discontinuous physiological trait governed by a single gene pair; Fingerprint pattern categories match discontinuous morphological trait uninfluenced by environment; ABO agglutinogen production matches discontinuous physiological trait determined by multiple alleles.
Each phenotype aligns precisely with its biological nature (morphological vs. physiological), distribution pattern (continuous vs. discontinuous), and underlying genetic mode of inheritance.
Step-by-Step Solution
Key Concept
Human Morphological and Physiological Variations (Continuous vs. Discontinuous)