Many cacti in the desert have thick, photosynthetic stems and few or no leaves (or leaves that are modified as spines). why is this body shape adaptive?

What is thought to have caused the mass extinction at the end of the cretaceous period?

The following hormone had their receptors in the cell membrane except a-insulin b-tsh c-gh d- cortisol

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.