Answer the following question given this paragraph: Vertebrates evolved from primitive chordates. This occurred about 550 million years ago. The earliest vertebrates may have been jawless fish, like the hagfish in Figure below . Vertebrates evolved a backbone to replace the notochord after the embryo stage. They also evolved a cranium , or bony skull, to enclose and protect the brain. Q: Vertebrates evolved from primitive forms of which creature? Choices: - arthropods - humanoids - cephalopods - chordates A:
chordates

Answer the following question given this paragraph: Q: The contents of which organ are mixed every 20 seconds? Choices: - the metabolism - pancreas - kidney - the stomach A:
the stomach

Answer the following question given this paragraph: Myriapoda, which includes centipedes and millipedes. All of these animals live on land, and can have anywhere from ten to nearly 200 pairs of appendages. Q: What class are centipedes and millipedes in? Choices: - xerophyte - spirogyra - terapoda - myriapoda A:
myriapoda