sentences: killing a living thing decreases the population of that living thing & hunting is when a human kills an animal for food / recreation in the wild & an animal is a kind of living thing ->  hunting / overhunting decreases animal populations  hunting / overhunting decreases animal populations & an animal is a kind of organism & if a population decreases to zero then that organism is extinct -> if hunting decreases the animal population to zero, then that animal is extinct