What are the seven elements that make up a small fraction of approximately 3.7% living cells

What must happen before meiosis can begin? a. four gametes must be produced b. the four tetrads must be pulled apart c. dna doubles and produces sister chromatids d. the cell membrane pinches together

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?

Why do we perceive objects as retaining their brightness under different lighting levels?