Biology: Genetics and Evolution Flashcards

A point mutation changes a codon from UAC (Tyrosine) to UAA (Stop). This is classified as a:

Answer: Nonsense mutation

A nonsense mutation changes an amino acid codon into a premature stop codon, truncating the resulting protein.

Two species of birds live in the same area but mate at different times of year, preventing interbreeding. This is an example of:

Answer: Temporal isolation

Temporal isolation is a prezygotic barrier where species breed at different times (seasons, times of day) and thus never interbreed.

In a population where p = 0.3 (dominant allele), what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Answer: 0.42

Heterozygote frequency = 2pq = 2(0.3)(0.7) = 0.42 under Hardy-Weinberg equilibrium.

Which cellular process produces gametes with half the chromosome number of the parent cell?

Answer: Meiosis

Meiosis reduces the chromosome number by half through two successive divisions, producing haploid gametes.

Analogous structures in unrelated species (e.g., wings of bats and insects) are evidence of:

Answer: Convergent evolution

Analogous structures arise independently in unrelated lineages that face similar environmental pressures, demonstrating convergent evolution.

A scientist finds that a gene has three alleles in a population. How is this possible given diploid organisms only carry two alleles per gene?

Answer: Multiple alleles exist in the population, though each individual carries at most two

Multiple alleles refers to more than two allelic variants existing in the population; each diploid individual still carries only two.

Which evolutionary process is demonstrated when a small group of individuals colonizes a new area, founding a population with reduced genetic diversity?

Answer: Founder effect

The founder effect occurs when a small subset of a population establishes a new colony, carrying only a fraction of the original genetic diversity.