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Genetic Variation & Change · Part 1 of 4
9 exam-style questions with model answers, plus 12 quick multi-choice questions — every question on this part of the standard, grouped by the 3 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
Define the terms allele, genotype and phenotype. State what is meant by a heterozygous individual.
A population of 200 beetles contains 240 copies of the dark allele and 160 copies of the light allele. Calculate the frequency of the dark allele, and explain why allele frequency is expressed as a proportion rather than as a count.
Two flax plants have identical genotypes for height, but one grows much taller than the other. Discuss how this is possible, and explain the implications for how natural selection acts on a population.
Define mutation, and state the difference between a gametic mutation and a somatic mutation.
Explain why mutation is described as the only source of new alleles, when meiosis also produces genetic variation.
A population of insects is repeatedly sprayed with an insecticide. Within ten years, most of the population is resistant. A farmer concludes that the insecticide caused the insects to mutate so they could survive. Evaluate this conclusion and give a fully correct account.
Name the three processes in meiosis that produce genetic variation, and state how many cells meiosis produces and how their chromosome number compares with the parent cell.
Explain how crossing over produces variation, and explain why it produces a kind of variation that independent assortment cannot.
Some plants can reproduce both sexually and asexually. Discuss the consequences for a population's gene pool of relying on each method, and evaluate which is better for long-term survival.