Final answer:
If crossing over during meiosis results in an unequal exchange of DNA at a locus coding for a protein, the resultant gamete may lack the gene necessary for producing that protein, potentially leading to protein deficiency in the offspring.
Step-by-step explanation:
During the process of crossing over, which occurs during prophase I of meiosis, there is an exchange of genetic material between non-sister chromatids of homologous chromosomes. This genetic recombination results in gametes that carry a unique combination of DNA from both parents. In rare cases, an unequal amount of DNA may be exchanged, which can result in one of the recombinant chromosomes lacking a gene that is responsible for the production of a certain protein. If a gene locus that codes for a particular protein is involved in this unequal exchange, it could lead to a gamete lacking the gene necessary to produce that protein. This would increase the risk of offspring derived from such a gamete to be deficient in the production of that specific protein.