Why does ice float on liquid water?

Most scientific questions are based on opinions. hypotheses. observations. experimental data.

The seed coat's most important function is to provide a) a nonstressful environment for the megasporangium. b) the means for dispersal. c) dormancy. d) a nutrient supply for the embryo. e) desiccation resistance.

Contrast how pollination is different among gymnosperms and angiosperms.