Transgenic animals are used to understand the contribution of genes in the development of diseases such as:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Cancer and cystic fibrosis
Transgenic animals carry a foreign gene put into their DNA. Some are made as models for human diseases, so that the role of genes in a disease can be studied and new treatments tried. Such diseases have a genetic basis.
Option (1) Cholera and typhoid — Incorrect. Both are bacterial infections spread through food and water, not diseases caused by the patient’s own genes.
Option (2) Elephantiasis and ringworm — Incorrect. Elephantiasis is caused by a filarial worm and ringworm by fungi. Both are infections.
Option (3) Cancer and cystic fibrosis — Correct. Both diseases depend on the person’s own genes, not on a pathogen. So a transgenic model animal can show how the genes contribute to them, and new treatments can be tried on it.
Option (4) Pneumonia and kala-azar — Incorrect. Pneumonia is caused by bacteria and kala-azar by a protozoan (Leishmania). Both are infections.
NCERT Extract:
Transgenic Animals – “… (ii) Study of disease: Many transgenic animals are designed to increase our understanding of how genes contribute to the development of disease. These are specially made to serve as models for human diseases so that investigation of new treatments for diseases is made possible. Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.”