Background: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico ( Figure below ). The U.S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf.

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Which zone would have more oxygen, zone A or zone B?
Answer: zone B

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Which zone would have less oxygen, zone A or zone B?
Answer: zone A

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Would zone A have less or more oxygen than zone B?
Answer: less

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Would zone B have less or more oxygen than zone A?
Answer: more

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: In which zone more organisms would grow, zone A or zone B?
Answer: zone B

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: In which zone less organisms would grow, zone A or zone B?
Answer: zone A

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Would zone A see less or more organisms than zone B?
Answer: less

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Would zone B see less or more organisms than zone A?
Answer: more

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Which zone is a result of algae overgrowth, zone A or zone B?
Answer: zone A

Situation: Greg is studying the environmental impact of agriculture. He noticed that in his own state a lake near agricultural lands has been declared as a dead zone. For his study Greg labeled this zone as zone A. Then he found near a national park in his state a lake is not declared as a dead zone. To further his study he labeled this zone as zone B.

Question: Which zone is not a result of algae overgrowth, zone A or zone B?
Answer: zone B