Ice floats<span> on water </span>because<span> hydrogen bonding makes liquid water unusually dense</span>
Answer:
notochord, a dorsal hollow nerve cord and pharyngeal slits.
<span> Human females produce gamete cells that each have one X chromosomes. </span>

In humans, the medulla region of the brain is mainly responsible for the regulation process of respiration. It is also called the respiratory rhythm centre. The chemosensitive area located near the respiratory centre sends signals across nerve impulses to alter the rate of expiration to eliminate compounds.
Organism are referred to as Pluripotent cells