A certain element has a half-life of 1,000 years. How much of a sample of this element remains after 2,000 years?

What best describes lactic acid fermentation?

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

How does upwelling affect coastal fisheries? upwelling damages nutrient supplies at coastal fisheries as the warm, nutrient-rich surface water is replaced by nutrient-poor, cold water. upwelling damages nutrient supplies at coastal fisheries as the cold, nutrient-rich surface water is replaced by nutrient-poor, warm water. upwelling improves the nutrient supply at coastal fisheries as the warm, nutrient-rich surface water replaces the nutrient-poor, cold water. upwelling improves the nutrient supply at coastal fisheries as cold, nutrient-rich water replaces the warm, nutrient-poor surface water.