Why is dna replication called a "semi-conservative" process?

What is the correct answer for the process of water eroding soil? rills, sheet erosion, gullies sheet erosion, rill, gullies gullies, rills, sheet erosion sheet erosion, gullies, rills

Hydrilla (hydrilla verticillata) is an invasive aquatic plant and one of the most serious aquatic pests in florida. hydrilla has already been introduced to hundreds of bodies of water throughout florida, hydrilla is difficult to control because it grows rapidly and survives in many different water depths and conditions. hydrilla • describe how hydrilla affects native plant and animal species. include both a biotic and an abiotic limiting factor. • suggest one biotic and one abiotic recommendation that could slow the spread of hydrilla

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?