Problem 15 - Objective Biology for NEET

Question

Match the Column: Column I A. Unipolar B. Bipolar C. Multipolar Column II 1\. Cell body with one axon only, found usually in the embryonic stage. 2\. Cell body with one axon and two or more dendrites, found in cerebral cortex. 3\. Cell body with one axon and one dendrite, found in retina of eye. (a) \(\mathrm{A}-1, \mathrm{~B}-3, \mathrm{C}-2\) (b) \(\mathrm{A}-2, \mathrm{~B}-1, \mathrm{C}-3\) (c) \(\mathrm{A}-3, \mathrm{~B}-2, \mathrm{C}-1\) (d) \(\mathrm{A}-1, \mathrm{~B}-2, \mathrm{C}-3\)

Step-by-Step Solution

Answer

The correct answer is \(a\) \(\mathrm{A}-1, \mathrm{B}-3, \mathrm{C}-2\).

Step 1: Understanding neuron structures

First understand how a Unipolar neuron is structured: it has a cell body with one axon only. Next, learn about Bipolar neurons: these have a cell body with one axon and one dendrite. Then, consider the Multipolar neurons: these have a cell body with one axon but multiple dendrites.

Step 2: Matching neuron structures with their descriptions

Match the different neuron structures to the descriptions given and link the options in Column I such as Unipolar, Bipolar and Multipolar neurons to the correct descriptions from Column II. Unipolar matches with \('Cell body with one axon only, found usually in the embryonic stage'\) which is option 1, Bipolar matches with \('Cell body with one axon and one dendrite, found in retina of eye'\) which is option 3 and Multipolar matches with \('Cell body with one axon and two or more dendrites, found in cerebral cortex'\) which is option 2. So the correct match is A-1, B-3, C-2.

Step 3: Determining the final answer

After comparing the matching done in Step 2 with the options given, it's evident that option \(a\) \(\mathrm{A}-1, \mathrm{B}-3, \mathrm{C}-2\) is the correct match

Key Concepts

Unipolar Neuron

Unipolar neurons are a type of neuron that plays a critical role during certain stages of development. These neurons are characterized by having a single process that emerges from the cell body. This process typically splits into two branches, one functioning as a dendrite and the other as an axon.

• Location: Unipolar neurons are commonly found during the embryonic stage.
• Function: They help with the early formation of the nervous system.

Their simple structure allows them to efficiently transmit nerve signals without need for complex processing. Unipolar neurons are crucial in the initial stages of nervous system development, guiding growth and formation of neural networks.

Bipolar Neuron

Bipolar neurons have a more complex structure compared to unipolar neurons. These neurons have two extensions stemming from the cell body: one axon and one dendrite.

• Location: Bipolar neurons are often found in the retina of the eye.
• Function: They play a significant role in sensory functions, particularly in vision and olfaction.

The dendrite of a bipolar neuron receives signals from sensory stimuli, such as light entering the eye. The axon then transmits this information to the brain, aiding in the process of perception. This dual-fiber structure is highly specialized for its function in transmitting sense information with precision.

Multipolar Neuron

Multipolar neurons are the most common type of neuron, known for their complex structure. They feature one axon and two or more dendrites emanating from the cell body, allowing them to integrate a vast amount of information.

• Location: Commonly found in the cerebral cortex and spinal cord.
• Function: They are involved in processing and transmitting information throughout the central nervous system.

The multiple dendrites allow multipolar neurons to receive numerous signals from other neurons. This ability makes them well-suited for handling complex processing tasks, such as those involved in cognition, sensory perception, and motor functions. Their presence in the cerebral cortex highlights their importance in higher brain functions.

Cerebral Cortex

The cerebral cortex is the outer layer of the brain, playing a pivotal role in numerous high-level functions. This region is highly convoluted, increasing its surface area and thus its capacity for complex processes.

• Composition: It primarily consists of gray matter, filled with neuron cell bodies, dendrites, and synapses.
• Functions: The cerebral cortex is involved in various functions such as sensory perception, generation of motor commands, and reasoning.

More complex neurons, like multipolar neurons, are abundant here, contributing to the region's ability to manage intricate processes. It is divided into different lobes which specialize in different functions, solidifying its role as a control center for many of the brain's activities.

Retina of Eye

The retina is a light-sensitive layer of tissue located at the back of the eye. It plays an essential role in vision by converting light into neural signals.

• Structure: It contains several layers of neurons, including photoreceptors, bipolar cells, and ganglion cells.
• Function: The primary function of the retina is to capture light and start the process of vision.

Bipolar neurons in the retina are integral to the visual pathway. They connect the photoreceptors—which respond to light stimuli—to ganglion cells, which relay the visual information to the brain. This layered structure ensures the efficient transmission and initial processing of visual signals, vital for clear vision.