exam questions

• Give the meaning of the term polygenetic (2)

  -       characteristic showing continuous variation 

  -       caused by multiple genes at different loci 
• explain how epigenetic changes affect the development of tissues in the embryo 

  -       DNA is wrapped around histones in a complex called chromatin 

  -       acetylation or histones causes DNA to unwind, allowing RNA polymerase to bind 

  -       methylation of DNA stops the transcription of genes 

  -       therefore, gene expression is altered
• explain how epigenetic changes can cause differences in a characteristic (3)

  -       DNA methylation or acetylation of histones 

  -       Affects the activation of genes, only genes activated are expressed

  -       Affecting enzyme production/metabolism 
• Explain how epigenetic changes affect the activation of genes in daughter cells (3)

  -       Genes are activated or deactivated in stem cells 

  -       Because of methylation of DNA or acetylation of histones 

  -       Therefore, the same genes will be activated in the daughter cells
• Explain why an individual may have a greater adult height than their biological parents (4)

  -       Height is affected by the environment as well as genotype 

  -       Height is an example of polygenetic inheritance 

  -       Thus offspring can inherit a mix of alleles from both parents which increase height

  -       Higher protein diet may a lot affect height