Animals can be classified into two main groups:vertebrates and invertebrates<span>. The main difference between </span>vertebrates and invertebrates<span> is that</span>invertebrates<span>, like insects and flatworms, </span>do<span> not</span>have<span> a backbone or a spinal column. Examples of</span>vertebrates<span> include humans, birds, and snakes. hope this helped</span>
Carbon-14 is the radioisotope that is used to determine the age of once-living organisms. Radioactive dating is a technique of comparing the abundance ratio of a radioactive isotope to a reference isotope to determine the age of a material. The mostly used radioisotope is carbon-14, because may rocks and organisms contain this radioisotope.
Enzymes and a single substrate use the lock-and-key mechanism.
The "lock" is the enzyme and the "key" is the substrate
