The balls move randomly.
Because gas molecules are known for their movement and the above statement says “to model the movement”
Explanation:
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<span>The molecules that provoke a specific immune response are called antigens.
</span>This molecule initiates the production of an antibody and causes an immune response. T<span>oxins, chemicals, bacteria, viruses, or other substances that come from outside the body can be part of the antigens.
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A tree is not an isolated system. It gets nutrients from surrounding environment to grow and build its mass. A total mass of tree plus its environment is constant.
Water is always cycling around, through and above the Earth in a natural water cycle that has existed for billions of years. As water moves between the land, ocean, rivers and atmosphere it changes from solid to liquid to gas. This natural water cycle is our planet’s way of recycling water, and is essential for life on Earth.
