Variable number of tandem repeats (VNTRs) in DNA are highly useful in which powerful molecular technique for identifying individuals and establishing biological relationships?

Introduction / Context:
Modern molecular biology has revealed that human and animal DNA contains many repeated sequences. Some of these repeats, called variable number of tandem repeats (VNTRs), differ greatly between individuals and form the basis of several powerful identification techniques. Examinations frequently ask where VNTRs are most usefully applied, especially in the context of forensic science and paternity testing. This question checks whether you can correctly connect VNTRs with the appropriate molecular technique.

Given Data / Assumptions:

• VNTRs are short DNA sequences arranged back to back in tandem repeats.
• The number of repeat units varies from person to person at a given location in the genome.
• The options include recombinant DNA technology, monoclonal antibody production, stem cell culture, and DNA fingerprinting.
• We assume standard definitions of these technologies as taught in biology courses.

Concept / Approach:
DNA fingerprinting (also known as DNA profiling) takes advantage of the fact that VNTR patterns are highly variable among individuals, except for identical twins. By comparing the sizes of VNTR-containing DNA fragments at several loci, scientists can generate a characteristic pattern or profile for each person. This pattern is widely used in forensic investigations, paternity disputes, disaster victim identification, and wildlife conservation studies. Recombinant DNA technology, monoclonal antibody production, and stem cell culture rely on different molecular principles and do not specifically use VNTRs as their central tool. Therefore, VNTRs are most directly and famously useful in DNA fingerprinting.

Step-by-Step Solution:
Step 1: Recall that VNTRs are short DNA sequences repeated in tandem, with the number of repeats varying among individuals. Step 2: Understand that this variation creates length differences in the DNA segments that contain these repeats. Step 3: In DNA fingerprinting, these regions are cut with restriction enzymes and separated by gel electrophoresis to produce a banding pattern. Step 4: This pattern is compared between samples from crime scenes, suspects, or family members to identify matches or relationships. Step 5: Match this description with the options and select DNA fingerprinting and forensic identification as the technique where VNTRs are highly useful.

Verification / Alternative check:
If you recall standard diagrams in genetics chapters, VNTRs are always illustrated in the context of DNA fingerprinting, with profiles shown side by side for different individuals. Recombinant DNA technology typically focuses on cloning genes, making plasmids, or expressing proteins, not on VNTR length variation. Monoclonal antibody production uses hybridoma technology, and stem cell culture deals with cell growth and differentiation, not with VNTR-based profiling. This consistent association of VNTRs with DNA fingerprinting confirms the correct answer.

Why Other Options Are Wrong:
Recombinant DNA technology to produce genetically modified crops is a broad genetic engineering method that may involve any genes, but does not specifically depend on VNTRs for identification. Monoclonal antibody production in hybridoma culture focuses on immune cells and antibody secretion, not DNA repeat analysis. Stem cell culture for regenerative medicine studies how stem cells divide and differentiate and is not centred on VNTR patterns. These techniques are important but do not use VNTRs as their core tool for identifying individuals.

Common Pitfalls:
A common pitfall is to see familiar advanced terms like recombinant DNA technology and assume that anything involving DNA must fall under that heading. Another mistake is to confuse general genetic modification with specialised identification methods. To avoid such errors, remember that VNTRs are specifically highlighted when you study DNA fingerprinting and forensic science. Linking VNTRs directly with DNA profiling will help you answer such questions with confidence.

Final Answer:
The correct option is DNA fingerprinting and forensic identification, because VNTRs provide highly variable DNA patterns that allow scientists to distinguish one individual from another.