Answer:
Index
Explanation:
An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify that period of time over a large area.
The venom of a black widow spider is toxic to the nervous system.
Answer:
In science, this is false. Powers of ten are the references to either scientific notations or measurements when comparing atoms in chemistry.
Answer:
I think it is Transduction
Explanation:
Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. An example is the viral transfer of DNA from one bacterium to another and hence an example of horizontal gene transfer.
Answer:
Environmental exposure to certain chemicals, ultraviolet radiation, or other external factors can also cause DNA to change. These external agents of genetic change are called mutagens.