patterns of inheritance Flashcards
outline the implications of the overuse of antibiotics to people that do not show symptoms (4 marks)
antibiotic = selection pressure
naturally their are bacteria that are antibiotic resistant because of genetic variation
resistant-bacteria survive
reproduce and pass on these beneficial alleles
population of antibiotic resistant bacteria increase
antibiotic doesnt have an effect new one needed
over time the average beak size available in a population depends on the seed size available explain how
beak size affects ability to eat seeds
birds with better suited beaks survive more
the pass on their beak size genes
over generation average beak size changes (directional)
It is thought that the modern cheetah population has low genetic diversity because the
population, relatively recently, experienced a genetic bottleneck.
Explain why a genetic bottleneck can lead to low genetic diversity.
alleles lost because of the drop in numbers of cheetah population
modern population descends from only a few survivors
Scientists are concerned about genetic drift in the remaining cheetah populations.
Explain why genetic drift is likely to be of particular concern in the population of 100 cheetahs in
Iran.
frequency of alleles decrease
some favoured more than others
alleles lost from population
environmental change e.g new disease leads to extinction
When the island of Madagascar became separated from the African continent, there were
no members of the cat family, Felidae, on the island.
Outline how a fossa could have evolved from a much smaller, mongoose-like ancestor.
allopatric speciation
different selection pressures
random mutation
survive / reproduce
alleles passed on
directional selection
Islands, such as Madagascar, often have species that are different from those on the
nearest land mass because they are reproductively isolated.
State three other conditions that must be present in order for speciation to occur
mutation
natural selection
time
Suggest how allele B inhibits the expression of allele A. (dominant epistasis)
codes for a repressor protein
blocks RNA polymerase from binding to promoter
no pigment produced
