Explain what must happen before a cell can divide

When analyzing tree rings, what do scientists assume a thin ring indicates?

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

The phylogenetic tree illustrates the relationship between humans and our closest living relatives. the tree was based on biochemical comparisons, including dna and amino acid sequences. according to the biomolecular data, we could infer that