Which idea did Ptolemy’s model use to explain why the planets appeared to move backward as they moved in their orbits?

Explain the side effects of cancer treatments

What links the two strands in a dna helix together in the middle? a. phosphate groups b. sugar rings bonded together c. proteins d. bases with hydrogen bonds

There are specialized producers that live in warm water vents deep in the ocean. these producers do not per-form from photosynthesis, but instead perform a similar process with iron and other chemicals. why do you think these producers use this process instead of photosynthesis?