Scientists test for alleles that cause human genetic disorders by a. making karyotypes. b. making dna fingerprints. c. detecting the dna sequences found in those alleles. d. making pedigrees.

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.

the sphincter muscles at the end of the digestive tract is the anus.