Organ system is the answer
Vance is demonstrating conceptual knowledge
Conceptual knowledge is the clear and detailed understanding of principles, concepts, models or theories and the understanding of the linking relationships between them. Conceptual knowledge is acquired by thoughtful, reflective learning, listening, reading, or viewing. From the question, Vance is demonstrating conceptual knowledge because he has the explicit understanding of why rainfall amounts affect different types of vegetation positively and others negatively.
The circulatory system - hemoglobin in the blood transports oxygen :)
The pancreatic juice is secreted by the pancreas. This pancreatic juice is secreted into the first part of the small intestine known as the duodenum. This pancreatic juice is rich in various enzymes that help in the digestion of various food components (carbohydrates, fats, and proteins). Besides being rich in enzymes, it is also rich in bicarbonate content. The bicarbonate works to neutralize the acidic chyme. This helps the enzymes to function and carry out digestion properly. If the pancreas fails to produce bicarbonate, then the function of enzymes will be altered, and the acidic chyme (coming from the stomach) will damage the small intestine walls.
