Which organism(s) are a part of every food chain?

Which of the following is not a classification of marine organisms? a. benthos c. neritic b. nekton d. plankton select the best answer from the choices provided a b c d i know the answer is not option b

What is the mrna strand that would be copied from this dna strand

Ablastocyst is a group of cells that forms after a human egg is fertilized. the blastocyst consists of two types of cells. some of these cells will become the placenta. what do the other cells develop into?