Instinct or learned behavior?
A bird building a nest.

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Fill in the blank with the best word to complete the sentence. white blood cells protect against and aid in blood clotting when injuries are sustained.

Add solid urea to a beaker of water. the beaker gets very cold. is δh favorable or