Muscles are indirectly attached to bones by means of

Which structure is the glomerulus?

Free nitrogen is released to the atmosphere by

The part labelled 3 is the

If the blood is too concentrated, more water is absorbed from

In a reflex action, impulse flows from

All the cell bodies in the spinal cord are found in

Hydra removes undigested food by

Viruses are considered to be living organisms because they