Variation within populations Knowledge-Based Download PDF

Questions

1. 1.

   Which of the following is an example of non-heritable phenotypic variation within a natural population?

   • A) Variations in human ABO blood types determined by inherited multiple alleles
   • B) Variations in plant height caused primarily by localized differences in soil nutrient availability
   • C) Variations in peppered moth coloration produced by alternative alleles of a pigment-regulating gene
   • D) Variations in sickle cell anemia susceptibility caused by a point mutation in the beta-globin gene
2. 2.

   Which characteristic distinguishes continuous variation from discontinuous variation in a natural population?

   • A) It produces distinct, non-overlapping phenotypic categories controlled by alleles at a single gene locus.
   • B) It forms an unbroken spectrum of phenotypes typically shaped by multiple additive genes and environmental influences.
   • C) It remains completely unaffected by environmental conditions throughout an individual's lifetime.
   • D) It is transmitted solely through maternal cytoplasmic inheritance rather than nuclear chromosomes.
3. 3.

   Which mechanism generates novel combinations of existing alleles in a sexually reproducing population without altering nucleotide sequences to create new alleles?

   • A) Genetic drift
   • B) Mitotic cell division
   • C) Directional selection
   • D) Crossing over during prophase I of meiosis
4. 4.

   Which biological process serves as the ultimate source of entirely new alleles, thereby introducing novel genetic variation into a population's gene pool?

   • A) Independent assortment during meiosis
   • B) Gene mutation
   • C) Random fertilization of gametes
   • D) Crossing over between homologous chromosomes
5. 5.

   Which statement best explains why genetic variation within a population is essential for the process of natural selection?

   • A) It guarantees that every individual organism develops identical physiological adaptations throughout its lifespan.
   • B) It prevents environmental pressures from causing differential survival and reproductive rates among members of the group.
   • C) It provides a range of diverse phenotypes so that some individuals are better suited to survive and reproduce when conditions change.
   • D) It eliminates all deleterious alleles instantly from the gene pool prior to any reproductive events taking place.