What is plastic texture in the earth's structure?

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

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.

The phylogeny chart shows the evolution of camels. camelus is the modern-day camel. based on this chart, which three statements are true? ⭕ modern camels are more related to stenomylus than to eschatius. ⭕ stenomylous and modern camels do not share a common ancestor. ⭕ modern camels are more related to camelops than to aepycamelus. ⭕ pliauchenia and oxydactylus may share similar features. ⭕ procamelus and stenomylous may share similar features.