What is an allele? Please hurry Thanks

Which animal group is the largest and contains more species from all the other living groups combined? is it mammals or

Atypical human cell is approximately 12.00 μm in diameter and enclosed by a membrane that is 5.000 nm thick. (a) what is the volume of the cell including the membrane? (b) what is the volume of the cell membrane? (c) what percent of the total volume does its membrane occupy? to simplify the calculations, model the cell as a sphere. enter your answers using four significant figures.

The kind of fertilization found in the majority of aquatic animals is (internal or external) fertilization.