Changes in temperature, salt concentration, ionic concentration, of pH levels
The answer is A. - Prokatyotic cells lack a defined nucleus while eukaryotic cells do have one :) I loved learning about the cells in biology! But I noticed your question is worded a little differently so the nucleus would be the one thing a eukaryotic cell has that a prokatyotic cell does not...
False in order for an ecosystem to survive there has to be some sort of competition. for example, if there were no sharks to eat little fish the little fish would over populate and then the little fish would run out of food which then means that whatever the little fish ate is now extinct and so on hinting the food chain's name. If it wasn't for competition nothing would survive