Why do tulips have different colours?

Who is at risk for STDs? Why is internal bleeding bad? Why is it advantage that fetal hemoglobin has a higher affinity for oxygen than maternal hemoglobin? What are the opportunities for advancement for oncology? Is it normal to have periods afte 45 days? Which process of bone repair relates to when the broken bones are reconnected by a soft template of tissue? Can woman that have been sterilized get pregnant? Do mosqitoes have a infection? How many people die a year of fat? Why are you getting blackheads? What is the enzyme in skin that gives it color? You are now twenty eight weeks pregnant when did you conceive? You are taking prenatal vitamins you heard that you can get too much Vitamin A. How much is too much your vitamins have 4800IU of Vitamin A and 25 percent as Beta Carotene...Is this ok? Dangers of having a house on the coast? Does swelling in the leg cause nerve damage? Where is folic acid found in? Will cipro treat cough and sore throat? Are labs prone to seizures? Why did King Philip II of Spain visit Philippines conquer it and name after himself during his lifetime? From where can one purchase a complete PA system?