What cells are in the Digestive system

What best describes lactic acid fermentation?

Creating new things to solve problems and improve life depends on the close interaction of which two fields?

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.