Two of the risk factors for down syndrome include which of the following?

What role does differential reproduction play in natural selection? ! a) some organisms have different reproductive success due to nongenetic traits. b) some organisms have traits that them reach reproductive age. c) different methods of reproduction result in some organisms being genetically altered. d) reproduction varies among organisms due to pathogenic factors. the answer is not a or d based on other posts.

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

This is one form of rna that transports a specific amino acid to a ribosome during protein synthesis.