The idea that plants have some degree of consciousness first took root in the early 2000s; the term "plant neurobiology was_____（1）around the notion that some aspects of plant behavior could be_____（2）to intelligence in animals. _____（3）plants lack brains, the firing of electrical signals in their stems and leaves nonetheless triggered responses that_____（4）consciousness, researchers previously reported.

But such an idea is untrue, according to a new opinion article. Plant biology is complex and fascinating, but it_____（5）so greatly from that of animals that so-called_____（6）of plants intelligence is inconclusive, the authors wrote.

Beginning in 2006, some scientists have_____（7）that plants possess neuron-like cells that interact with hormones and neurotransmitters,_____（8）"a plant nervous system,_____（9）to that in animals." said lead study author Lincoln Taiz, "They_____（10）claimed that plants have 'brain-like command centers' at their root tips."

This_____（11）makes sense if you simplify the workings of a complex brain,_____（12）it to an array of electrical pulses; cells in plants also communicate through electrical signals._____（13）, the signaling in a plant is only_____（14）similar to the firing in a complex animal brain, which is more than "a mass of cells that communicate by electricity." Taiz said.

"For consciousness to evolve, a brain with a threshold_____（15）of complexity and capacity is required," he_____（16）"Since plants don't have nervous systems, the_____（17）that they have consciousness are effectively zero."

And what's so great about consciousness, anyway? Plants can't run away from_____（18）. So investing energy in a body system which_____（19）a threat and can feel pain would be a very_____（20）evolutionary strategy, according to the article.