What is the first change that occurs in a sensory neuron following an external stimulus like touch, light, or heat?

Which experiment would most likely contain experimental bias ?

In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a ) moss sporophyteb) moss gametophyte bearing both male and female gametangiac) fern sporophyted) fern gametophyte bearing only antheridia

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine