![]() ![]() Sexual reproduction is important for promoting variation as even though mutations form new genes or alleles, sexual reproduction forms a new combination of alleles. 5.4.6 Explain how sexual reproduction promotes variation in a species. 5.4.5 State that the members of a species show variation. This results in an increase in mortality rate as the weaker individuals in the population will lose out on these vital resources that are essential for their survival. If there is an over production of offspring this will result in a struggle for survival within the species as the resources become scarce and individuals in the population will start to compete for these. As more offspring are produced, there will be less resources available to other members of the population. ![]() If the mortality rate remains lower than the natality rate then a population will keep growing. 5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival. Populations tend to produce more offspring than the environment can support. 5.4.3 State that populations tend to produce more offspring than the environment can support. Many bones in the limbs are common to a number of species and therefore suggests that these have evolved from one common ancestor. Finally scientists have found a number of homologous structures within different species. This suggests that not only have these animals evolved but also that they can evolve rapidly. An example of this is the taming of wild wolves and their selective breeding in order to produce the domestic dogs we know today. As selected wild individuals with desirable characteristics were bred, over time this resulted in a more desirable species from a human point of view. Selective breeding of domesticated animals also provides this evidence as the domestic breeds have similar characteristics to the wild ones and can still breed with them. This suggested that organisms changed over time. As they started to study fossils they realised that these were not identical but had similarities with existing organisms. 5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.įossils, selective breeding and homologous structures have provided scientists with evidence that support the theory of evolution. Chromosomes, genes, alleles & mutationsĮvolution is the cumulative change in the heritable characteristics of a population. ![]()
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