(i)what relationship seems to exist between the number of species of snail present and the concentration of calcium in the water?

(ii) Give a possible explanation for this relationship based on the fact that one of
the components of a snail's shell is calcium

answer; i believe the correct answer to the above question is ( friction)

c. heat from the poles back down towards the equator.

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.