Allele frequency, speciation and conservationEdexcel International A Level Biology: Flashcards

What these 15 flashcards ask

State the two Hardy-Weinberg equations.
In the Hardy-Weinberg equation, what do p², 2pq and q² represent?
In what order do you calculate Hardy-Weinberg values from the percentage with the recessive phenotype?
State the conditions for Hardy-Weinberg equilibrium.
What does a change in allele frequency between generations show?
What is genetic drift?
Define mutation.
How does natural selection change allele frequency?
Define species.
What is allopatric speciation?
Describe how a new species forms after a population is divided.
Give two ways that reproductive isolation can occur without a geographical barrier.
Give two roles of zoos in conservation.
Why are seed banks a cheap way to conserve plants?
State a limitation of captive breeding.

Exam questions on Allele frequency, speciation and conservation

In a large population of beetles, body colour is controlled by one gene with two alleles: a dominant allele G for green and a recessive allele g for brown. 16% of the beetles are brown. Assume that the population is in Hardy-Weinberg equilibrium.
State two conditions that must be met for the frequency of the alleles in the beetle population to stay the same from one generation to the next.2 marks
Ground squirrels live on both sides of a deep canyon that was cut by a river over thousands of years. The squirrels cannot cross the canyon. The north side of the canyon has wet forest and the south side has dry scrub. Today the squirrels on the two sides differ in coat colour and in the frequencies of many alleles.
Explain how the canyon could have led to the formation of two species of ground squirrel.2 marks
Warfarin is a poison that is used to kill rats. Before warfarin was first used in a farming region, an allele R that gives resistance to warfarin was very rare, with a frequency of 0.001 in the rat population. After 15 years of continuous use of warfarin, the frequency of allele R in the rat population was 0.6.
Explain how the frequency of allele R increased in the rat population.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).