Which of the following did not evolve during the mesozoic era? mammals dinosaurs birds none of the above

An uncomfortable feeling in the ears when descending in an airplane is caused by changes in air pressure on the: a. inner ear b. middle ear c. eardrum d. hammer/anvil

Embryonic stem cells are cells derived from an embryo. these cells can be used to create new tissues for patients suffering from certain illnesses and disorders. which statement best summarizes why the use of embryonic stem cells could be seen as unethical? a. some people consider embryos to possess rights equal to those of fully developed human beings. b. extracting stem cells from embryos is a very energy-intensive process, which consumes resources that could be used elsewhere. c. embryos are difficult to obtain, so the monetary cost of using them for research outweighs their benefit. d. the process of extracting stem cells from embryos generates biohazardous waste that cannot be safely disposed of.

Abotanist working in the amazon rain forest discovers a new species of orchid. interestingly, males but not females of a certain wasp species keep visiting the flowers of these orchids. why?