Read the following passage carefully and answer the given questions.
Immune System in the Body
The human immune system consists of lymphoid organs, tissues, cells and soluble molecules like antibodies. The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes. After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix. The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells. The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Hence, an antibody is represented as H2L2. Different types of antibodies are produced in our body. IgA, IgM, IgE, IgG are some of them. Techniques like radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs.
Which one of the following technique is not useful for the detection of cancers of internal organs?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → DNA fingerprinting
Option (1) Radiography — Useful for detecting cancers of internal organs. Radiography uses X-rays to take pictures of the inside of the body. A tumour shows up as an unusual mass on the X-ray film.
Option (2) CT — Useful for detecting cancers of internal organs. CT (computed tomography) also uses X-rays. It builds a three-dimensional image of the internal organs, so a tumour deep inside can be seen.
Option (3) DNA fingerprinting — Not useful for detecting cancers of internal organs. DNA fingerprinting compares the patterns of repetitive DNA of two people. It is used to identify a person, as in crime cases and disputes over who the parents of a child are. It gives no picture of any organ, so it cannot show a tumour.
Option (4) MRI — Useful for detecting cancers of internal organs. MRI (magnetic resonance imaging) uses strong magnetic fields and non-ionising radiations. It detects changes in living tissue with accuracy.
Note 1: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
Note 2: A similar question was also asked in CUET (UG) 2025 on 20-05-2025 (Slot 2).