Question

Which of the following applies to the brain of most animals?
A) Within the brain neurons exchange information with one another
B) Brains usually lie as near as possible to the important sensory organs in an animal
C) Brains send action potentials to the hindmost portions of the animal by means of major nerves
D) All of the above

Answer 1

Hint: In lower animals, where the nervous system may just have a nerve knot or ganglion, these may be situated in different parts of the body, rather than a central processing unit. Brains are the highest level of evolution.

Complete answer:
The correct answer to this question is (D). Let’s see how this works.
Neurons exchange information with one another to allow for sensory and motor processing, coordination of bodily functions, and so on. The brain is essentially a giant mass of neurons coordinating everything. Therefore A is correct.
From very primitive chordates to higher vertebrates, from invertebrates to mammals, those with brains tend to have them located in the head region. This is also the point where sensory organs like the eyes, the nose, and the auditory organs/ears are located. Sensory information needs to be processed very quickly, which is why these organs are in close proximity to the brain. Option B is correct.
C is also correct. Via large motor neurons, we get our toes and feet to move. Through large sensory neurons, information from the extremities is picked up. Cutting of major nerves affects the functioning of different parts of the body, from the most proximal to the most distal.
Putting all this information together, D is the correct answer – all of the above.

Hence the correct answer is OPTION(D)

Note: Though the brain is the central processing unit, some functions can occur without initially being processed by the brain. A good example is the spinal reflex arc, where we react to a noxious stimulus before the brain records and stores and gives a more permanent solution.