Why are the veins blue if our blood is red?

Blood is always red, actually.

Explanation:

Veins look blue because light has to penetrate the skin to illuminate them, blue and red light (being of different wavelengths) penetrate with different degrees of success. The oxygen-rich blood is then pumped out to your body through your arteries

Veins look blue because light has to penetrate the skin to illuminate them, blue and red light (being of different wavelengths) penetrate with different degrees of success.

Explanation:

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.

a scenario where a cell may be needed to perform a form of endocytosis is when transporting large molecules. a scenario where a cell may be needed to perform a form of exocytosis is when releasing the large molecule from the cell.