Answer:
any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights. There are 275 isotopes of the 81 stable elements, in addition to over 800 radioactive isotopes, and every element has known isotopic forms. Isotopes of a single element possess almost identical properties.
Explanation:
Answer:
b. forward mutation, suppressor mutation
Explanation:
When the nucleotide sequence of an organism is altered, it is called as mutation. It can be caused by DNA damage or replication errors. In forward mutation, the wild type allele is converted to a mutant version such that the gene product is non functional or its not produced at all. Suppressor mutation is the second mutation which reverses the phenotypic effects of the previous mutation. This process is called as synthetic rescue.
Since here gene X was converted into a mutant form by the mutation, it had undergone forward mutation. When gene Y was mutated, the function of gene X was restored which ultimately also restored the phenotype hence it is an example of suppressor mutation.
The mechanism that affected the gene pool of the immigrants that entered the United states Through Ellis Island is Gene flow.
Gene flow involves the movement of genes or alleles between interbreeding populations of a particular species. In other words it is the movement of genes from one population to another population. Actually it may be an important aspect of evolution; evolution can occur as a result of genes being transferred from one population to another. Gene flow occurs when there is migration, since the loss or addition of people can easily change pool frequencies even without no other evolutionary mechanisms operating.