1. What is density dependence, and why is it important in multicellular
organisms?

It is when the population growth rates are regulated by density of a population. This is important in a multicellular organism for several reasons. It would affect the birth and death rates of the organism.

Explanation:

they deliver oxygen to the blood

the answer is admiramos

the rule for verbs is whoever you are referring to (in this case 'nosotros'), you need to change the ending of the word.

nosotros - amos

yo - o

tu - as

el, ella, usted - a

ellos, ellas, ustedes - an

(examples: nosotros bailamos (instead of bailar) or yo hablo (instead of habla)