Trace elements, what are they?

This program originates from the ballroom of the Lord Baltimore Hotel where alumni are celebrating the 77th anniversary of the Johns Hopkins University. Lynn Poole opens the program by paying special tribute to Elmer V. McCollum, who discovered vitamins A and B, and John Lee Pratt, who donated money to establish the McCollum Pratt Institute of the University. Using a periodic table, Dr. McElroy points out the macronutrients (nitrogen, phosphorous, potassium, magnesium, sulfur, calcium, and sodium) and the micronutrients or trace elements (copper, manganese, iron, and zinc). In addition to these, animals need cobalt and iodine to thrive and plants need boron and molybdenum. Both a diagram and an animation show how a nutrient deficiency in the soil may not affect plant health but won't be passed on to humans or animals and therefore could adversely affect them (e.g., lack of iodine in the soil may result in goiter in a human).