Final answer:
To confirm a child's relation to parents, matching bands in the DNA fingerprints of the parents and child are required. To verify the incorporation of foreign DNA into a host organism, specific genetic identification techniques are used. Selective markers help to differentiate cells with external DNA from those without it.
Step-by-step explanation:
The question requires an understanding of genetic inheritance and the identification of organisms using DNA fingerprinting. When establishing a biological relationship, especially in a parental test, the child's DNA fingerprint must have bands that match those of both the mother and father. This indicates that the child has inherited DNA fragments from each parent. For the second part, designing a plan to determine if foreign DNA has been incorporated into the host organism's DNA necessitates procedures such as polymerase chain reaction (PCR), Southern blotting, or sequencing to identify the presence of the new DNA sequences within the host's genome. Lastly, differentiation between cells that have taken up external DNA from those that have not can be accomplished through selective markers that allow only the cells with incorporated DNA to survive or be identified under specific conditions.