As an action potential occurs, the neuron's electrical charge changes from to a. negative; more negative b. positive; negative c. negative; positive d. positive; more positive

The correct answer is option C, that is, from negative to positive.  

Action potentials are those electrical impulses, which transmit signals around the body and are nothing more than a temporary shift, that is, from negative to positive in the neuron's membrane potential resulting due to the flowing of ions in and out of the neuron suddenly.  

During the resting state, that is, prior to an action potential, all of the gated potassium and sodium channels are closed. They open once an action potential has been initiated. The sodium channel opens and more sodium ions move within the cell, making the charge more positive.  

1. amino acid refers to the fundamental building block of proteins, comprising of an amino group and a carboxyl group.

2. catalyst refers to any substance, which increases the rate of chemical reaction without being used up in the reaction.

3. a complex molecule containing he genetic code is dna or deoxyribonucleic acid.

4. an enzyme refers to a molecule of protein, which is unique in accelerating up a particular chemical reaction in the biological systems.

5. nucleic acid refers to an sequence of sugars, phosphates, and nitrogenous bases, for example, dna and rna.

6. a protein refers to a large, composite organic molecule comprising of a huge number of amino acids associated together with the of peptide bonds.

7. rna refers to a nucleic acid that takes part in the production of proteins.

8. substrate refers to a compound, which takes part in a chemical reaction, and is chemically modified by the reaction.