Which of the following is correct regarding the pH scale?

An efferent neuron that is responsible for releasing a neurotransmitter that stimulates a muscle cell to contract is a motor neuron ². Motor neurons carry signals from the brain to the peripheral nervous system in order to initiate an action ⁴. The neurotransmitter acetylcholine (ACh) is released by motor neurons at the neuromuscular junction in skeletal muscle, causing the muscle to contract ³.

The other options are not correct because they do not accurately describe the type of neuron responsible for releasing a neurotransmitter that stimulates a muscle cell to contract. Interneurons are found within the central nervous system and facilitate communication between sensory and motor neurons. Sensory neurons carry information from sensory receptors to the central nervous system. Neuroglia are support cells for neurons and do not transmit nerve impulses.

Most of the carbon dioxide from the blood moves into the alveoli by diffusion down a concentration gradient ¹. Carbon dioxide is always carried in the blood and is released into alveolar air during expiration ¹. Respiratory gases move from higher concentration to lower concentration ¹. In alveolar air, when carbon dioxide is less than in blood, carbon dioxide is released ¹.

The other options are not correct because they do not accurately describe the process by which most of the carbon dioxide from the blood moves into the alveoli. Passive transport using carrier proteins, active transport using energy, and conversion to carbon monoxide are not the processes responsible for moving most of the carbon dioxide from the blood into the alveoli.