Question

Aquatic photo diffraction produces zones, like:
(A) Euphotic, disphotic, and disphotic
(B) Aphotic, euphotic, and disphotic
(C) Euphotic, Aphotic, and disphotic
(D) Euphotic, disphotic, and aphotic

Answer 1

Hint:The pelagic zone comprises the water column of the ocean, which is divided into regions by depth depending on the amount of light penetration. Most of the Solar energy reaching the earth falls under the range of visible light, i.e. they have wavelengths between 400 to 700 nm. The waters very effectively observe this incoming light. The amount of light being penetrated into the ocean decreases with an increase in depth.

Complete answer::
As mentioned that the amount of solar energy penetrating the ocean waters depends on the depth, it has been determined that at a depth of about one meter, only 45 percent of solar energy is present. Similarly, at a depth of 10 meters, only 16 percent of solar energy is present and about only 1 percent of solar energy is present at a depth of 100 meters. Beyond 1000 metres, there has been no account of light penetration. Based on this, the ocean is divided into zones called the euphotic zone (photic zone), disphotic zone, and the aphotic zone.
The euphotic zone is also known as the photic zone for sunlight zone is the uppermost layer which receives an ample amount of sunlight. This allows the phytoplanktons present on the surface of the water to perform photosynthesis. To supply nutrients into the upper water column the phytoplanktons undergo a series of physical, chemical and biological processes. Majority of aquatic life is present in the zone. This zone extends from the surface down to a depth where light intensity falls to 1 per cent of that at the surface. This depth is known as the euphotic zone. About 90 per cent of all marine life lives in the photic zone. The disphotic zone is the zone which extends from the base of the euphotic zone to about 200 metres below. The photic zone and the disphotic zone together are known as the epipelagic zone. The aphotic zone is the bottommost zone. It is present below the euphotic zone and it has been determined that most of the deep ocean waters belong to the zone.

Based on the particulars provided, the correct answer is option D. Euphotic, disphotic and aphotic.

Note: The open ocean appears clear and blue because it contains less particular matter such as phytoplankton or other suspended particles. Because of the clarity of the water, more light is able to penetrate into the ocean. The water appears blue because blue light penetrates deeply into the water and is scattered by the water molecules, whereas the other colours are absorbed. Compared to the open ocean and coastal waters contain more suspended particles and organisms such as algae. These organisms observe blue and red light due to the photosynthetic pigments present in them. This leaves green light as the dominant wavelength of reflected light. Therefore, water appears greener if the rate of phytoplankton concentration in water is high.