Answer:
The evidence suggests that these chloroplast organelles were also once free-living bacteria. The endosymbiotic event that generated mitochondria must have happened early in the history of eukaryotes, because all eukaryotes have them
Explanation:
google
Answer:
A signal is sent from a nerve cell to a muscle cell
Explanation:
I just took this test and this was the correct answer.
Answer:
Neither observer nor subjects know which subject receives the vaccine and which receives a placebo
Explanation:
In a double-blind study neither the participants nor the experimenters is aware of who is receiving a particular treatment.
Its used to prevent bias in research results from demand characteristics or the placebo effect
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