What is different with retroviruses in reproduction is that they do not kill their hosts at first because they can still insert their own genome. This process is what is known the reverse transcription. This is done by different proteins.
No blacks are 100% human.. people are black because of the pigments in your skin. That is why we have light skins and dark skins not because light skins are more human than dark skins.
Its .. Nervous tissues i think i still remember cause i had this question on an exam and i got it right lol ..
- But hoped i helped you out any .. if anymore help is need just ask me then .
Thats true _____________________________________________________