Answer:
A system of two co-axial cylindersof different diameters which rotate together is called wheel and axle example; the door knob , knob of the tap ,screw driver,water tap
B. Circulatory, respiratory, nervous
Answer: B
Explanation: Hemoglobin is a protein in red blood cells that acts as the vehicle for oxygen and carbon dioxide from the lungs to tissues and vice-versa.
What is considered normal Hemoglobin levels vary throughout one's life, from childhood to adult life and in older adults. It even varies between women and men. In women, it also varies depending on whether they are pregnant or not.
When hemoglobin does become less than normal, it results in anemia, a condition accompanied by fatigue. Because the athlete does not have this symptom, he is not suffering from anemia, and so there is no cause for concern. Although the athlete's hemoglobin level has reduced, the absence of fatigue indicates that it is not lower than normal.
I'm too sure about this question but I think the answer to this is 4.0026
His nerves joints and bones control his movement
