Read the following passage and answer the following questions:
Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe. More than a million Indians suffer from cancer and a large number of them die from it annually. The mechanisms that underlie development of cancer or oncogenic transformation of cells, its treatment and control have been some of the most intense areas of research in biology and medicine. Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost this property. As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumors. Transformation of normal cells into cancerous cells may be induced by carcinogens. Radiations cause DNA damage leading to neoplastic transformation. Cancer causing viruses called oncogenic viruses have genes called viral oncogenes. Cancer detection is based on biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts in the case of leukemias. Techniques like radiography, CT and MRI are very useful to detect cancers of the internal organs. The common approaches for treatment of cancer are surgery, radiation therapy and immunotherapy.
Which of the following non-ionizing radiations cause DNA damage leading to neoplastic transformation?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → UV rays
Radiations that damage DNA are of two kinds. X-rays and gamma rays are ionising radiations. UV rays are non-ionizing, yet they too damage DNA and can lead to neoplastic transformation. The passage says only that radiations cause DNA damage; it does not sort them.
Option (1) X-rays — Incorrect. X-rays are ionising radiations. They do cause DNA damage, but they are not non-ionizing.
Option (2) Gamma rays — Incorrect. Gamma rays are also ionising radiations, so they do not fit the question.
Option (3) UV rays — Correct. UV rays are the non-ionizing radiation named in the book that causes DNA damage leading to neoplastic transformation.
NCERT Extract:
Cancer – “Causes of cancer : Transformation of normal cells into cancerous neoplastic cells may be induced by physical, chemical or biological agents. These agents are called carcinogens. Ionising radiations like X-rays and gamma rays and non-ionizing radiations like UV cause DNA damage leading to neoplastic transformation.”