Problem 99 - Objective Biology for NEET

Question

Vitamin A combines with a protein in the retina to produce (a) Glaucoma (b) Night blindness (c) Rhodopsin (d) Colour blindness

Step-by-Step Solution

Answer

Hence, the correct answer is (c) Rhodopsin.

Step 1: Understanding Vitamin A's role

Vitamin A, a vital nutrient obtained from the diet, has multiple functions in our body. One of its significances lies in the process of vision. Vitamin A, also known as retinol, is essential for maintaining the health of the retina.

Step 2: Identifying the Compound

Vitamin A, when absorbed by the body, combines with a protein called opsin available in the retina. The combination of these two forms rhodopsin, which is also known as 'visual purple'.

Step 3: Analysing the Options

With the knowledge of how Vitamin A functions in the retina, one can analyse the given options. Glaucoma and Colour blindness are diseases and they are not produced by the combination of Vitamin A and a protein in the retina. Night blindness is a condition that can occur due to the deficiency of Vitamin A. However, it is not produced by the combination of Vitamin A and a protein. The product of these two specific compounds, as discussed, is Rhodopsin.

Key Concepts

Rhodopsin

Rhodopsin is an essential molecule in the process of vision. It is a complex of the protein opsin and a derivative of Vitamin A called retinal. Rhodopsin is also referred to as "visual purple," owing to its light-sensitive nature. Located in the rods of the retina, rhodopsin plays a crucial role in converting light into electrical signals that the brain can interpret. This transformation is fundamental for us to see, especially in low-light conditions, such as at night or in a dimly lit room.

• Comprises opsin and retinal.
• Enables vision in low-light environments.
• Located primarily in the rod cells of the retina.

The presence of rhodopsin allows for the detection of faint light, enhancing our night vision capabilities. Without an adequate amount of Vitamin A, rhodopsin cannot form efficiently, leading to difficulties in vision, such as night blindness.

Retina

The retina is a thin layer located at the back of the eye. It is crucial for our ability to see the world around us. Essentially, the retina functions similarly to a film in a camera, capturing images and translating them into signals.

• Composed of layers of cells, including rods and cones.
• Converts light into neural signals.
• Plays a pivotal role in visual perception.

Rod cells are particularly important for vision in low-light conditions, while cone cells handle color vision and detail. The proper function of the retina is dependent on nutrients like Vitamin A, which supports its overall health and functionality. Damage to the retina can impair our ability to see clearly and sharply.

Vision process

The vision process starts when light enters the eye through the cornea and passes through the pupil. This light is then focused by the lens onto the retina, where photoreceptor cells (rods and cones) come into play.

• Light is focused on the retina.
• Photoreceptors convert this light into electrical signals.
• The optic nerve transmits signals to the brain.

Once the photoreceptors in the retina detect light, they convert it into electrical signals. These signals are then transmitted to the brain via the optic nerve. The brain processes these signals, resulting in the image we perceive. The formation of rhodopsin with the help of Vitamin A is crucial for our ability to see in dim light, making this nutrient essential for the vision process.

Opsin protein

Opsin protein is vital in the biology of vision. It is a protein found in photoreceptor cells of the retina, primarily the rods and cones. Opsin binds with retinal (a form of Vitamin A) to form rhodopsin in rod cells.

• Opsin is a light-sensitive protein.
• Combines with retinal (Vitamin A) to form rhodopsin.
• Different opsins help in detecting different wavelengths of light.

In addition to forming rhodopsin, opsins are also found in cone cells and help in color perception. Each type of opsin in cones is sensitive to different wavelengths of light, which contributes to our ability to see various colors. Proper functioning of opsin proteins is necessary for both low light and color vision, making them indispensable in the complex process of seeing.