Why do we need the chemical level in addition to the biological level?

• A. Chemicals can affect behaviour
• B. Chemicals have no effect on behavior
• C. Chemicals replace biological processes
• D. Chemicals only relate to taste

Answer: (A)

Chemical signaling shapes behavior by modulating neural activity and bodily responses. The biological level looks at the structure and function of the nervous system—brain regions, neurons, synapses—while the chemical level focuses on the molecules that carry messages between cells, such as neurotransmitters and hormones. These chemicals can influence whether neurons fire, how strongly they fire, and how long the signal lasts, which changes thoughts, feelings, and actions. For instance, dopamine pathways play a key role in motivation and reward, serotonin influences mood, and cortisol affects stress responses. Because chemicals can alter the strength and timing of brain signals, they are essential to understanding behavior in addition to the underlying biology. If chemicals are ignored, you miss how states like excitement, fear, hunger, or fatigue arise from signaling changes, not just from brain structure. The statement that chemicals have no effect is incorrect; that they replace biological processes is wrong; and that they only relate to taste is too narrow and inaccurate.