Which of the following is NOT a characteristic of a population?

• A. Number of individuals
• B. Phenotype
• C. Sex ratio
• D. Age distribution

Answer: (B)

Phenotype is related to the observable traits or characteristics of an individual organism, such as its physical appearance or biochemical properties, which are influenced by its genetic makeup and environmental factors. While phenotypes can vary significantly within a population, they do not define the population itself.

In contrast, the number of individuals, sex ratio, and age distribution are all fundamental characteristics that describe a population. The number of individuals gives insight into the population size, while the sex ratio provides information on the proportion of males to females, which can impact reproduction rates. Age distribution reflects the proportions of individuals in different age categories, which plays a crucial role in understanding population dynamics and growth potential. Therefore, phenotype, being an individual-level trait, does not qualify as a characteristic of a population.