Answer:
b. Antibodies are used for Northern blot analysis.
c. VNTRs are highly conserved in human populations.
Step-by-step explanation:
The northern blot technique is used in molecular biology laboratories for detecting specific RNA molecules in a sample of RNA derived from a particular cell/tissue. Antibodies can be detected by the enzyme-linked immunosorbent assay (ELISA). In ELISA, antigens are used to detect specific antibodies: the addition of the antigen produces a positive reaction i.e., formation of the antigen-antibody binding complex. Subsequently, a second antibody with a particular marker is added to bind with the complex, thereby producing a change in the color and thus evidencing the presence of the target antibody in the sample. On the other hand, the variable number of tandem repeats (VNTR) are short sequences (around 20 to 100 bp) whose number of repetitions varies at specific loci in the genome of many organisms, including humans. Since VNTR sequences exhibit variation in length between individuals of the same species/population, they are widely used as molecular markers to identify individuals, QTL (quantitative trait loci) mapping, establish phylogenetic relationships among individuals/cultivars/lines, etc.