Limestone contains calcium carbonate which comes from animals that have shells, it already has carbon. Other sources are ocean animals which create shells that combine both carbon and calcium. Their dead bodies also release carbon to the ocean. Limestone is also known as a sedimentary rock that has carbon. Outside the ocean, limestone emits the carbon and becomes part of the carbon cycle. In addition to this, limestones are widely used by people becomes a part of the carbon cycle. Its component is present on asphalt, animal feed.
They are different in structure as one serves in an open system (lymphatic system) while the other serves is closed system (circulatory system).
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*This question is common, so this answer I use a lot. I copied my own work.*
This is because the melanocytes are located in the stratum basale. Lighter-skinned people usually have low basal levels, and exposure to UV radiation causes an increase which makes skin darker.
A law is something that can be measured or observed to be true. A theory, is something that can be assumed to be true based on the best available knowledge.