Entrance Exams
Govt. Exams
Interference = 1 - Coefficient of Coincidence = 1 - 0.8 = 0.2. This measures how much one crossover interferes with adjacent crossovers.
In small populations, genetic drift can cause alleles to be randomly lost. With frequency only 0.02 in a population of 100, the allele is vulnerable to random loss.
Mutations in non-coding regions vary in importance. Those in regulatory elements (promoters, enhancers) can be significant; most others are neutral.
For X-linked traits in males (hemizygous), allele frequency equals phenotype frequency. In females at equilibrium, the allele frequency is the same as in males: 0.1
Bottlenecks drastically reduce population size, increasing genetic drift. Random allele loss occurs, reducing genetic variation and increasing chance of fixation.
Darwin's finches underwent adaptive radiation, diverging from a common ancestor into multiple species with different beak morphologies adapted to different food sources.
Cross: AS × AS produces AA (unaffected, 1/4), AS (carrier, 1/2), SS (affected, 1/4). Probability of unaffected = 1/4 + 1/2 = 3/4 = 0.75
If one dominant homozygous class (AABB, AABb, or AAbb) is lethal, the 9:3:3:1 ratio adjusts accordingly. Common outcome is 9:3:4 when one class is removed.
Lower recombinant frequencies indicate genes are linked but can undergo crossing over, producing recombinants at lower frequencies than parentals.
Gene flow (migration) introduces alleles from one population to another, counteracting genetic drift and maintaining genetic variation.