Similarities and differences between frogs and humans excretory system

Fossils can only be formed when? if mud, silt or tar is in the area to preserve the fossil ierosion does not occur and allows the fossil to form oxygen and microorganisms cannot decay the bones the area is dry and does not contain mud or silt

Contrast how pollination is different among gymnosperms and angiosperms.

What best describes the dropping height of a ball that bounces back up to a height of 45 cm