A scientist uses materials in her lab to cut a DNA sample into fragments.
What process is the scientist using
A. Karyotyping
B. Polymerase chain reaction (PCR)
c. Use of restriction enzymes
D. Gel electrophoresis

An example of internal feedback working to maintain homeostasis is your a. decreased respiration rate when you are studying b. decreased heart rate when you are sad c. increased respiration rate when your muscles need more oxygen d. increased heart rate when your lungs need more oxygen

What type of appendages do sponges cnidarians roundworms annelids mollusks arthropods echinoderms and vertebrate have? jointed, not jointed, absent  

Si units are the modern form of the