Question

question 10 of 25
how is a species defined?
a. by the total number of chromosomes
b. by the number of common ancestors
c. by the fixed alleles in the species
d. by the allele frequency in the population

Explanation:

A species is defined by having fixed alleles. Fixed alleles are alleles that are present in all members of a population at a particular locus. This is a key characteristic in species definition.

• Option A: The total number of chromosomes can vary within a species (e.g., due to polyploidy in plants) and also different species can have the same number of chromosomes.
• Option B: The number of common ancestors is more related to evolutionary relationships (phylogeny) rather than the strict definition of a species.
• Option D: Allele frequency in a population can change over time (e.g., due to evolution, genetic drift) and is not the basis for species definition.

Answer:

C. By the fixed alleles in the species