Match List-I with List-II:
| List-I (Cancer-related term) | List-II (Example / description) |
| A. Chemical agent | I. X-rays and gamma rays |
| B. Physical agent | II. Genes of normal cells that can lead to oncogenic transformation when activated under certain conditions |
| C. Biological agent | III. Carcinogens present in tobacco smoke |
| D. Proto-oncogenes | IV. Viruses carrying viral oncogenes |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-III, B-I, C-IV, D-II
(A) Chemical agent — this matches (III) Carcinogens present in tobacco smoke. The chemical carcinogens in tobacco smoke are a major cause of lung cancer.
(B) Physical agent — this matches (I) X-rays and gamma rays. X-rays and gamma rays are ionising radiations. They damage DNA and can turn normal cells into cancer cells.
(C) Biological agent — this matches (IV) Viruses carrying viral oncogenes. Oncogenic viruses are living agents. They carry viral oncogenes, genes that can cause cancer.
(D) Proto-oncogenes — this matches (II) Genes of normal cells that can lead to oncogenic transformation when activated under certain conditions. Proto-oncogenes, also called cellular oncogenes (c-onc), are present in normal cells. They cause no harm until they are activated; then they can turn the cell cancerous.
NCERT Extract:
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. The chemical carcinogens present in tobacco smoke have been identified as a major cause of lung cancer. Cancer causing viruses called oncogenic viruses have genes called viral oncogenes. Furthermore, several genes called cellular oncogenes (c-onc) or proto oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells.”