From the time a fertilized egg is implanted in a mother's uterus until about the eighth week of pregnancy, the developing organism is called a/an

a. placenta.
b. embryo. ( i think its this one. not sure.)
c. zygote.
d. fetus.

You are correct, it is an embryo. I'm pretty sure the child is called a fetus for the rest of the pregnancy.

Eukaryotic cells are theorized to have evolved from prokaryotes called the endosymbiotic theory. this explains that the most primitive eukaryotic cell engulfed a prokaryotic cell (by the process of phagocytosis) that is capable of cellular respiration and another prokaryotic cell that is capable of photosynthesis. these prokaryotic cells eventually became organelles and these organelles are the mitochondria and the chloroplast