Quite unrelated groups have evolved similar secondary compounds independently, and this is true for orange and parsnip. Go back to question 7 or go on to question 8a . They are weak bases and have a bitter taste. Go back to question 8a or go on to question 8b . Go back to question 8b or go on to question 8c .
Hallucinogens are psychoactive chemicals that change perception.
They may be alkaloids or nonnitrogenous compounds, and they interfere with neurotransmission in various ways. Go back to question 8c or go on to question 8d . Pungency is not a taste but a sensation, a hot burning feeling in the lining of the mouth and back of the toungue. It may be caused by capsaicin in capsicum-type peppers or other compounds in ginger or black pepper. Go back to question 8d or go on to question 8e .