Transcript Evolution
Evolution Past Paper Questions 1. Explain the factors that cause a population to follow the sigmoid ( Sshaped) growth curve. (8 max) 1. Explain the factors that cause a population to follow the sigmoid ( S-shaped) growth curve. (8 max) • • • • • • • • • • • during exponential growth the population grows at an increasing rate all / most / many offspring survive / birth rate higher than death rate all / most / many offspring reproduce each generation produces more offspring that the last plateau reached eventually / population levels off / birth rate equals death rate when carring capacity of environment is reached e.g. when no more food / nutrients / resources available e.g. when no more space for nesting / space for another purpose is available e.g. when numbers of predators have increased e.g. when levels of parasites / diseases have become very high transitional phase when limits to growth are starting to act 2. Apply the concept of carrying capacity to the struggle for survival resulting from overproduction of offspring. (5 max) 2. Apply the concept of carrying capacity to the struggle for survival resulting from overproduction of offspring. (5 max) • the environment can only support a certain maximum population • this population is sometimes exceeded (due to overproduction of offspring) • food / space / resources are insufficient / competition for resources • some individuals fail to obtain enough • deaths / failure to reproduce / survival of the fittest • population falls to carrying capacity • reference to evolution by natural selection 3. Discuss the definition of the term species. (8 max) 3. Discuss the definition of the term species. (8 max) • • • • • • • • • • • • • species is a group of organisms a species shares a common gene pool showing similar morphology / characteristics capable of interbreeding and producing fertile offspring but dissimilar organisms sometimes interbreed mule formed by crossing horse and donkey / other example of interspecific hybridisation interspecific hybrids are sometimes fertile sometimes organisms that are very similar will not interbreed Drosophila pseudoobscura and persimilis / other example of sibling species reference to the problem of defining fossil species reference to the problem of species that only reproduce asexually reference to the problem of isolated populations gradually diverging 4. Outline two modern examples where evolution can be observed. 2 marks 4. Outline two modern examples where evolution can be observed. 2 marks • • • • • change of beak shape in Galapagos finches resistance to pesticides/antibiotics bird predation on moths heavy metal tolerance in plants melanism in ladybird beetles 5. Outline one modern example of observed evolution by natural selection. 2 marks 5. Outline one modern example of observed evolution by natural selection. 2 marks • named example • selective pressure • Result example • beaks of Galapagos finches • competition for food • change in numbers/proportion of birds with different sized beaks 6. Outline five types of evidence which support the theory of evolution by natural selection. 6 marks 6. Outline five types of evidence which support the theory of evolution by natural selection. 6 marks • • geographic distribution ring species/other evidence from geographical distribution • • biochemistry cytochrome c/other biochemical evidence • • fossils/paleontological fossilized horse ancestors/other evidence • • homologous structures pentadactyl limb/vertebrate embryos/other • • recent observed evolution resistance to antibiotics/insecticides/heavy metal tolerance/other recent example 7. Explain the evidence from homologous anatomical structures that supports the theory of evolution. 6 marks 7. Explain the evidence from homologous anatomical structures that supports the theory of evolution. 6 marks • homologous structures are various different structures of the same basic plan • derived from a similar embryonic origin • variations on the basic structure allow different functions • permitting exploitation of differnt ways of life/adaptive radiation • the suggests divergence from a common ancestor • named example of a homologous structure (e.g. pentadactyl limb, flower, birds` beaks) • description of basic structure of this example • variation related to different functions of this example