The main parts of the peripheral nervous system are . A. the brain and spinal cord
B. nerves
C. the skull and backbone
D. all of the above

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

African penguins, which inhabit the coasts of southern africa, were classified as an endangered species in 2010. two significant threats to their survival are ecosystem damage from oil spills and overfishing by humans. overfishing depletes the food supply of african penguins. the best method to reduce the threat of overfishing would be to . the risk of oil spills could be reduced by increasing the use of , which should oil consumption. if an oil spill does occur, could be used to remove the oil so the ecosystem may more quickly recover.

Which of the following would involve looking at different structures of organisms and comparing how similar they are? a. vestigial structuresb. radiometric datingc. homologous structures