Final answer:
True, Mutation rates are indeed generally higher in bacteria compared to vertebrates, as bacteria have higher reproduction rates and simpler repair mechanisms. Beneficial mutations, such as antibiotic resistance, and harmful ones occur. Mutations can arise spontaneously and are not always due to toxic substances.
Step-by-step explanation:
The statement that mutation rates are higher overall in bacteria than in vertebrates is true. Bacteria reproduce rapidly and have simpler genome maintenance mechanisms, which often result in higher mutation rates compared to the slower reproduction and more complex genome repair mechanisms of vertebrates. An example of a beneficial mutation in bacteria is the development of antibiotic resistance, allowing bacteria to survive exposure to antibiotics. A harmful mutation might impair essential functions, leading to decreased survival. Mutations can be caused spontaneously or by exposure to mutagens like cigarette smoke, which can damage DNA and lead to cancer. It is false that mutations are always caused by exposure to toxic substances; they can occur randomly without external influences. Furthermore, some mutations can indeed make chromosomes longer or shorter, as seen in various genetic conditions and the normal variation within populations.