Which of the following layers of skin lack blood vessels?

The result of using a catalyst in a chemical reaction is that the reaction is completed in a shorter amount of time. A catalyst is a chemical substance that affects the rate of a chemical reaction by altering the activation energy required for the reaction to proceed. This process is called catalysis. A catalyst provides an alternative pathway for the reaction, one that has a lower activation energy than the uncatalyzed pathway.

The other options are not correct because they do not accurately describe the result of using a catalyst in a chemical reaction. A more desirable product is not necessarily formed, a greater amount of heat energy is not necessarily released by the reaction, and the yield of the product is not necessarily increased as a result of using a catalyst.

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.