TASK DEFINITION: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
PROBLEM: Waste builds up in the blood. Blood enters the kidney. Blood passes through nephrons in the kidney. Different kinds of waste are momentarily trapped in the kidney. Cleaned blood flows out of the kidney. Filtered waste accumulates in liquid form (urine). Urine flows out of the kidney into the bladder. 

SOLUTION: waste ,blood ,cleaned blood ,filtered waste ,urine 

PROBLEM: Warm, moist air moves from south to north. Cool, dry air moves from north to south. The air masses meet. The conditions that form are not stable because the air masses are so different. Winds are directed in a certain way because of how the masses interact. An updraft results. Winds start to form circular patterns in the updraft. A tornado can result. 

SOLUTION: warm, moist air ,cool, dry air ,air masses ; masses ,wind ,updraft ,circular patterns ,tornado 

PROBLEM: A flowering plant has stamen and pistils. An insect ot bird lands on the plant. Some of the pollen sticks to it. The insect or bird travels to another plant of the same species. The pollen is tranferred to the new plant. 

SOLUTION:
stamen and pistils ,pollen