When the race is almost to begin, nervous system sends signals to the heart causing the respiratory rate to increase. since there is an increase in heart rate, breathing and sweating becomes increases in order to maintain a normal body temperature.
the answer is a it can be used as an energy source by organisms
These organelles group together to eventually form cells, or the basic units of all living things.
Organelles are specialized structures in the cytoplasm of cells which provide essential cell functions and are composed of different molecules (macromolecules). Cells as the smallest basic units of life are then grouped in tissues (similar cells which provide a specific function), layers of different tissues work together to provide specific function and form organ, organ group in organ systems which then compose the whole organism.
