Jellyfish do not have a central nervous system.
Squids which belongs to Cephalopoda (class of Mollusca) have the most complex nervous system of the invertebrates. They have well-developed senses and large brains. So, they are considered as the most intelligent of the invertebrates.
Dolphins, on the other hand, are regarded as one the most intelligent animal.
Answer:
The answer is true, the pumping of hydrogen ions decreases and finally stopps.
Explanation:
As the cyanide blocks the bindinge site for oxygen, which is normally reduced to water, the pumping of hydrogen from the matrix into the space between the mitochondrial membrane decreases and finally stopps. There is an accumulation of electrons and the components of the respiratory chain are completely reduced, therefore the respiratory chain stopps working.