What is the force that moves rock and other materials downhill called?

Plants are used for so many things. in your house alone, you can probably look around you and see where plants have been used. for this project, you will identify various uses of plants in your home. directions make a list of objects, products, and any other items around your house where plants were involved in the production of the item. you should have a list of at least twenty items. then respond to the following questions: note: your list of objects and the answers following should be at least 200 words in length. what if plants no longer existed on earth? how would your life be different?

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Ascientific idea becomes valid when it is what?