Final answer:
Chromosomal deletions can lead to changes in phenotypes because they result in the loss of genetic material. This can alter the expression of genes responsible for certain traits or functions, leading to abnormal phenotypes. The imbalance in gene dosage caused by deletions can also affect cellular processes and contribute to phenotypic changes.
Step-by-step explanation:
Chromosomal deletions can lead to changes in phenotypes because they result in the loss of genetic material. When a portion of a chromosome is deleted, the genes within that region are also lost. These genes may play important roles in determining certain traits or functions in an organism. As a result, the absence of those genes can lead to altered phenotypes.
For example, if a gene responsible for producing a specific protein necessary for normal development is deleted, the individual may exhibit abnormal physical features or developmental abnormalities.
In addition, chromosomal deletions can disrupt the balance of gene dosage. This means that the ratio of gene products may be altered, which can affect the normal functioning of cellular processes. This imbalance can further contribute to changes in phenotypes.