Final answer:
The exchange of segments of DNA during meiosis is called crossing-over, which is a source of variation within a species by creating recombinant chromosomes with mixes of maternal and paternal genes. While it can sometimes result in genetic disorders, it usually contributes to diversity. The correct answer is option a.
Step-by-step explanation:
Meiosis and Genetic Variation
The exchange of segments of DNA between members of a pair of chromosomes during meiosis, notably during prophase I, is known as crossing-over or recombination. This critical process occurs when homologous chromosomes pair up and exchange different segments of their genetic material, leading to recombinant chromosomes. Such crossing-over increases genetic variation as the resulting chromatids after the exchange are no longer identical, which ensures a mix of maternal and paternal genes in the gametes.
Genetic variation is essential for evolution and the survival of species as it provides a mechanism for populations to adapt to changing environments. It also explains why individuals within the same species can have different phenotypic traits. Moreover, while crossing-over can sometimes lead to genetic disorders if errors occur, it most often contributes to the natural diversity seen within a species.
The correct answer to the student's question is 'c) Acts as a source of variations within a species'. This recombination results in gametes that have different combinations of genes than those of the parents, thereby contributing to the genetic diversity within a species. It's important to understand that while errors in meiosis can lead to genetic disorders, the process of crossing-over itself is a normal and essential source of genetic variation.