To be clasified as an animal an organism must you have a backbone

What happens when the cell copies its chromosomes

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures

Ture or false evidence for evolution includes millions of fossils