Context: Genetic engineering is now a routine research tool with model organisms. For example, genes are easily added to bacteria and lineages of knockout mice with a specific gene's function disrupted are used to investigate that gene's function. Many organisms have been genetically modified for applications in agriculture, industrial biotechnology, and medicine.

Question: What has become a common research tool with model organisms?
Answer: Genetic engineering

Question: What do scientists explore by adding genes to mice with a certain gene's function disrupted?
Answer: that gene's function

Question: What is an application for which organisms have been modified for?
Answer: agriculture

Question: What is another for which  organisms have been modified for?
Answer: industrial biotechnology

Question: What is yet another application for which  organisms have been modified for?
Answer: medicine