The organs of the heart and the blood vessels form which of the followings ?

a. a cell
b. a tissue
c. an organ
d. an organ system

Check all that apply diatoms are marine algae that have a shell made of silica, what are some of the uses of the silica shell after the diatoms die? 1.the shells make up the diatomaceous earth used in filters 2.it can be used as an ingredient in abrasives 3.they are used in food products 4.the shells can be used in some insulating materials

Advances in technology have enabled scientists and researchers to better study the evolutionary relationships between species

Which animal is a producer in this ecosystem