front 1 What is a polygenic trait? | back 1 A trait caused by the effect of multiple alleles from different genes. |
front 2 What is an example of a polygenic trait? | back 2 Eye colour, body size, skin colour, type-2 diabetes, weight, hair colour... |
front 3 What is pleiotropy? | back 3 When a single gene affects multiple traits (as opposed to a single gene affecting a single trait) |
front 4 What is it called when the expression of one gene is controlled by other genes? | back 4 Epistasis |
front 5 What makes a population susceptible to genetic drift? | back 5 A small number of individuals. |
front 6 What is allopatric speciation? | back 6 The evolution of new species because of geographic isolation. |
front 7 Give an example of allopatric speciation. | back 7 One species is separated into two populations because of rising sea levels. They don't interact for a very long time. Sea levels lower again and the two populations can no longer interbreed. |
front 8 What is sympatric speciation? | back 8 When new species arise despite a lack of geographical isolation. |
front 9 What is a gene? | back 9 A gene is a region of DNA that codes for specific proteins. |
front 10 What are alleles? | back 10 Different forms of a particular gene. |
front 11 What is the difference between an allele and a gene? Which is composed of the other? | back 11 An allele is a location on a chromosome that codes for the expression of a specific trait. It encompasses the genes that influence the proteins that express that trait. |
front 12 An individual with two different alleles of a particular gene is said to be __________________ for that gene while an individual with two identical alleles is said to be ________________. | back 12 heterozygous, homozygous |
front 13 Which pair of alleles is homozygous and which is heterozygous? 1. Aa 2.bb | back 13 1. heterozygous 2. homozygous |
front 14 When both alleles contribute to the phenotype, the alleles are said to be what? | back 14 Codominant |
front 15 If one allele masks the expression of the other the expressed allele is said to be ______________ while the masked allele is said to be _____________. | back 15 dominant, recessive |
front 16 What are mutations? | back 16 Random changes in DNA the sequence of nucleotides of DNA. They can compromise a gene or control its expression. |
front 17 How might mutations increase genetic variation? | back 17 They may create different phenotypes within a population, increasing the amount of alleles they have. |
front 18 The reshuffling of genes that can occur during meiosis is called what? | back 18 Genetic recombination |
front 19 How might genetic recombination increase genetic variation? | back 19 Despite no new genes being created there is the potential for new combinations of alleles to produce new phenotypes. |
front 20 What is sexual reproduction? | back 20 When 2 parent organisms combine sex cells to produce offspring that are genetically distinct. |
front 21 How might sexual reproduction increase genetic variation? | back 21 By combining random portions of either parents' DNA each offspring is genetically distinct from each other with combinations of traits that could be beneficial or not. |
front 22 What is genetic drift? | back 22 A random process that occurs when genetic variation is lost because of random variation in mating, mortality, fecundity, and inheritance. |
front 23 What is the bottleneck effect? | back 23 A reduction in genetic variation because of a severe reduction in population size |
front 24 What is the founder effect? | back 24 When a small fraction of a bigger population colonize a new area but only bring a fraction of their original genetic diversity. |
front 25 What are the three types of selection? What traits do they favour and punish? | back 25 Stabilizing selection: Favour intermediate, punish extremes Disruptive selection: Favour extremes, punish intermediates Directional selection: Favours one extreme only, punishes the other extreme and the intermediate |
front 26 Scenario: A graph shows the fitness of snails compared to how thick their shells are. The graph shows that thicker shelled snails have a higher fitness. What type of selection are the snails undergoing? | back 26 Directional selection |
front 27 Of the 3 types of selection only _________________ selection changes the mean frequency of a trait. | back 27 Directional |