A person can have hundreds of different type of cells because: different cells result from genetic variation in meiosis. different cell types have different genes. different cell types all have the same genes but have different genes active. None of these choices is correct.

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

1) a

2)c

3)a

4)c

5)b

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