Dissolving the sugar cube in water is a physical change. It doesn't alter the sugar's chemical structure like burning it or breaking it down with acid.
Neutrophils, because they are quick-response immune cells that recognize and destroy bacteria.
Answer:
When heart rate or rhythm changes are minor
Your heart rate or rhythm can change when you are under stress or having pain. Your heart may beat faster when you have an illness or a fever. Hard physical exercise usually increases your heart rate, which can sometimes cause changes in your heart rhythm.
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The theory of fluid intelligence is based on the distinction between the fluid and crystal intelligences. The crystal intelligence is based on the knowledge that one has already and the the fluid intelligence is the intelligence to respond to future and unpredictable challenges.
I think that this distinction is very fitting and that the fluid intelligence was probably the one that drove human evolution; and perhaps is the more relevant of the intelligences.
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