A student is conducting an investigation to find out which food his dog likes best. Which is the dependent variable in his investigation

the dependent vaiable would be the dog. the independent would be the type of food you are using. the independent vaiable is something you can change and you can not change the dog.

. fibrinogen is soluble in water and is found in high concentrations in the blood, where it waits until needed to form a clot

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.