Asubstance changes state from solid to liquid. what has happened? a physical change a chemical change a chemical reaction the creation of matter

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

Idon’t know the answer and i’ve been stuck on it for a while now skskskskks

Which of the following words best matches this definition: the process in which the best adapted organisms survive and pass on their traits, while those that are not well adapted do not survive to pass on their traits. question 3 options: acquired selection natural selection artificial selection organic selection