Many plants have thorns on their stems or leaves. what is the most likely explanation for the evolution of thorns?
a) thorns plants produce more food from photosynthesis.
b) thorns are an example of a mutation that arises in the genetic code of plants.
c) thorns plants to conserve resources like water and soil nutrients that may be used by other organisms.
d) thorns are an adaptation that some plants have evolved in order to discourage herbivores from eating the plant.

Melting glaciers is a serious threat to the environment what is the possible consequence of melting glaciers on polar bears?

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.

Which is one example of a phenotypic change that is not genetic