A scientist is searching for chemical compounds involved in embryonic limb development. He discovers a new compound that is transiently expressed in the limbs and only seems to affect cells in its immediate vicinity (up to a few cell lengths away). How should the scientist classify this chemical compound

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

Which group of molecules are targeted by the kinases in order to control this movement

Which best describes this behavior? it is beneficial only to the males that do not fertilize eggs. it is beneficial only to the female workers that are not fertilized. it is beneficial to each one of the individual colony members. it is beneficial to the whole species, but not to all of the individual members.