What substances must animal cells take in from the environment to maintain homeostasis?

Select all the true statements about the cosmic microwave background radiation

1. which of the following is correct regarding opiates/opioids: a. they all have a natural component as a starting pointb. they have low addiction possibilitiesc. methadone binds to some of the same receptorsd. a and care correcte. all are correct

In which situations is the principle of cross-cutting relationship useful in determining relative age?