Why are current radiation and chemotherapy treatments not always effective in preventing the reoccurrence of cancer?

Which of these parts of the membrane large moecules pass through it ?

What is any method of measuring the age of an object or event in years, such as using atomic half-life?

The table below shows data for a population of fish in a pond. fish body color # of fins scales? tail shape a silver 4 yes fan b pink 4 yes flat c black 4 yes fan d orange 4 yes flat e orange 4 yes fan f silver 4 yes flat which of the above characteristics would be most in developing a classification system for the fish? a. body color and tail shape b. presence of scales and tail shape c. body color and number of fins d. number of fins and presence of scales