I dont think it is symbiotic, it is parasitic relationship. They get blood supply of human and dont give anything useful to humans
Answer:
amino acids
Explanation:
proteins are organic matter molecules that perform multitude of function in the body
Answer:
B. Black fur
Explanation:
The last two options are normal to a bird.
Answer:
Muscles contract through a chain process of electrochemical signalling between the nervous system and muscles.
Explanation:
The muscle contraction is initiated by the nervous system by sending a signal. This signal also referred to as action potential travel through the motor neuron. This motor neuron releases a chemical signal to muscle when the electrical signal carried by it reaches the neuromuscular junction (a junction where motor neuron meets the muscles).
The chemical message referred to as neurotransmitter binds to the receptors present on the muscle fibers. These receptors causes the influx of sodium ion which in turn trigger the release of calcium ion thereby initiating the contraction of muscles.
