I need help, please!

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

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

All individuals have two alleles for a given trait. according to mendel's these alleles are passed down one each from both mother and father.