DNA Fingerprinting and Human Genetic Variation — NEET Biology
📚 Practice ConceptAs stated in the preceding section, 99.9 per cent of base sequence among humans is the same. Assuming human genome as 3 × 109 bp, in how many base sequences would there be differences? It is these differences in sequence of DNA which make every individual unique in their phenotypic appearance. If one aims to find out genetic differences between two individuals or among individuals of a population, sequencing the DNA every time would be a daunting and expensive task. Imagine trying to compare two sets of 3 × 109 base pairs. DNA fingerprinting is a very quick way to compare the DNA sequences of any two individuals.
Which of the following statements about VNTRs and their role in DNA fingerprinting are NOT correct? S1: VNTRs are a class of minisatellite DNA characterized by a small DNA sequence arranged tandemly in many copy numbers. S2: The copy number of VNTRs is generally identical across all chromosomes within an individual, leading to a consistent banding pattern. S3: These repetitive sequences typically code for essential proteins, contributing directly to an individual's phenotypic traits. S4: High degree of polymorphism in VNTRs refers to the variability in their repeat numbers, making them unique identifiers. S5: DNA from monozygotic twins would exhibit identical VNTR banding patterns due to their shared genetic origin.
View solution & NCERT explanation
Correct answer: B — S2 and S3
The core concept involves the characteristics of VNTRs and their significance in DNA fingerprinting. S1: VNTRs (Variable Number of Tandem Repeats) are indeed a class of satellite DNA, specifically minisatellites, where a small DNA sequence is arranged tandemly in multiple copy numbers. This statement is correct. S2: The NCERT states that 'The copy number varies from chromosome to chromosome in an individual'. This variability contributes to the unique fingerprint pattern, rather than identical copy numbers across all chromosomes. This statement is NOT correct. S3: The NCERT explicitly mentions that 'These sequences normally do not code for any proteins'. Their function is not in coding for proteins but rather in showing polymorphism for identification. This statement is NOT correct. S4: The high degree of polymorphism in VNTRs is precisely due to the variability in the number of tandem repeats, which makes them highly individual-specific markers. This statement is correct. S5: Monozygotic (identical) twins originate from a single zygote and therefore share identical genetic material, including their VNTR patterns. Hence, their DNA fingerprints would be identical. This statement is correct. Based on the analysis, statements S2 and S3 are NOT correct.
What does NCERT say about As stated preceding section?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.