The student created an accurate model of calcium carbonate. The model includes the correct number of gumdrops for each element in calcium carbonate, consistent use of colors for elements in calcium carbonate, and the correct number and placement of toothpicks (bonds).

3авиипп

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.