"Totipotency lasts for only a few days before the cells' fates are set as being the precursors to a specific lineage of cells." What does this sentence mean? Restate in your own words.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements