Answer:
The decline was attributed to a number of factors including Increased insect resistance, the development of more effective alternative pesticides, public and user concern about negative environmental side effects—and a government ban on DDT use since 1969--all contributed to the decline.
A) a common ancestor
Homologous structures are structures that are similar in related organisms. There is a basic pattern of bones which can be inherited from a common ancestor
The beneficial uses of bacterial toxins in medicine are more and more used lately. For example, Botulinum toxin is a toxic protein produced by the bacterium Clostridium botulinum which has paralytic effects (injection of this toxin into muscle relax specific muscles). Botulinum toxin accomplishes his effects on the neuromuscular junction where he prevents the release of the neurotransmitter acetylcholine (Ach). Utilization of this toxin is in the treatment of various muscle spasms. It is also used in the treatment of migraines. Diphtheria toxin is also one of the toxins used for medical purposes for the treatment of cutaneous and non-Hodgkin T-cell lymphomas. <span>Some bacterial toxins can be used in the treatment of tumours. For example, immunotoxin, which is protein made by fusion of modified antibody and toxin.The antibody binds to an antigen on the target cell, the toxin then enters via endocytosis and kills the cell. Commonly used bacterial toxins in immunotoxins are Diphtheria toxin and the Pseudomonas exotoxin.</span>
B. It insulates the fish from the cold air above
Just like an igloo
