1) Scientists believe that the ancient ancestors of all animals were <span>single-celled eukaryotes that sometimes grew in colonies.
</span>Eukaryotic cells have membrane-bound organelles such asmitochondria<span> and the Golgi apparatus.
</span>The best answer is :
<span>B) single-celled eukaryotes that sometimes grew in colonies</span>
The 3 checkpoints include G1 where the cell growth is checked, G2 where the integrity of the DNA/chromosome is checked, and M where the integrity of the metaphase plate is checked.
<h3>Cell cycle checkpoints</h3>
There are 3 regulatory checkpoints in the life cycle of cells:
- G1: the size of the cell, the presence of growth factors, and the integrity of the DNA are checked before the cell irreversibly commits to division.
- G2: the integrity of the DNA and the correctness of the replication process at the S-phase are checked.
- M: correct attachment of the spindle fibers to the chromosomes at the metaphase plate is checked.
More on cell cycle checkpoints can be found here: brainly.com/question/2128300
Density - Calculated from measurements of mass and volume
Atom - the basic particle of matter
Motion - calculated from measurements of distance and time
Energy - can change form and move matter
Can't see the last one but you know process of elimination soo
