What are the basic building blocks of the cell membrane called?

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

In the ocean why are the greatest amount of primary producers found in the epipelagic zone and how does that affect biodiversity

What type of plant is good for a bioassay and where can i buy it? i only have a month.