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Patterns of inheritance Typeit

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While the genotype of an organism refers to the genetic information of that individual, the describes their observable characteristics. A is a length of DNA that codes for a polypeptide, and many of them come in different forms, called alleles. Individuals with two of the same allele for a certain characteristic are known as for that characteristic. Alleles which express themselves whenever they are present are called alleles. Some alleles are found only on the sex chromosomes, but alleles located on any other chromosomes are called .

A may occur when a population rapidly decreases in size and then recovers, and the describes what happens when a few individuals which are not representative of a whole population form a separate colony and increase in number. In both cases, genetic diversity of the new population may be substantially reduced. The principle can be used to determine the frequency of different alleles in these populations, as long as all the assumptions are met.

There are two main types of natural selection which can act on populations:

  • selection favours the average phenotype when conditions are fairly constant
  • selection favours one extreme over another when conditions begin to change

  • In addition to this, humans have been imposing another form of selection on certain species over thousands of years in order to domesticate animals and produce desirable crops – this is known as . In some cases this has led to the evolution of a new species from an existing one, called .

    characteristics, such as blood group, have clearly distinguishable forms and are usually determined solely by genes, often a single gene. Other characteristics, such as height, may be influenced by a combination of several genes and the environment, and are , with quantitative variation and a range of intermediates.

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    Pass Mark
    69%