FREE NEET Biology Practice MCQ Test: Neural Control And Coordination Exercise 4 Questions Answers With Detailed Explanations [PDF]

Answer: (a)

Neurotransmitters are involved in the transmission of impulses at the chemical synapses. They are present in the synaptic vesicles at the axon terminals.

Hormones are non-nutrient chemicals which act as intercellular messengers produced in trace amounts.

Cerebrospinal fluid is present in the subarachnoid space. It provides shock resistance to brain.

Lymph is a colourless fluid containing specialised lymphocytes which are responsible for the immune responses of the body. It is an important carrier of nutrients, hormones, etc. Fats are absorbed through lacteals (lymph vessels) present in microvilli of intestine.

Answer: (c)

Answer: (b)

Sympathetic nervous system forms a part of autonomic nervous system that consists of nerves which connect the visceral receptors and effectors with the central nervous system through the cranial and spinal nerves. Sympathetic nerves arise from thoracolumbar nerves.

Answer: (b)

Answer: (c)

A bipolar neuron has one dendrite and one axon. It is found in the retina of eye.

Answer: (a)

The velocity of nerve impulse is approximately 100 m. per second and velocity of cardiac impulse is about 0.6 m. per second.

Answer: (c)

Statements (i), (ii) and (iii) are the main functions of cerebrum. Cerebrum is the largest and most highly developed part of the human brain. The outer portion of the cerebrum is covered by a thin layer of gray tissue called the cerebral cortex. It is divided into right and left hemispheres that are connected by the corpus callosum. (iv) Cerebrum controls the hearing and sense of smell through the temporal lobe.

Answer: (d)

Answer: (b)

Answer: (a)

Answer: (d)

Answer: (a)

Iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. The colour of the iris gives the eye its colour. In optical terms, the pupil is the eye's aperture and the iris is the diaphragm that serves as the aperture stop.

Answer: (b)

Photoreceptors in human eye are unique because they are only type of sensory cells that are relatively depolarised (about –35mV) when it is at rest (i.e., in the dark), and hyperpolarised (to about –70mV) in response to adequate light stimulus. Nociceptors respond to potentially damaging stimuli that result in pain. Meissner's corpuscles are a type of mechanoreceptor, responsible for touch sensitivity. Receptors generally produce graded potentials called receptor potentials.

Answer: (d)

Answer: (b)

Answer: (b)

Answer: (a)

Answer: (a)

Answer: (b)

Answer: (b)

Parkinson's disease is caused by degeneration of neurons in substantia nigra tract which are essentially dopaminergic. This striatum controls muscle tones and coordinates movements. An imbalance is caused by deficiency of dopamine (an inhibitory neurotransmitter) vis-a-vis.