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Which part of the body of mollusks possesses a visceral hump?
(a) Ventral side of the foot.
(b) Mantle cavity
(c) Dorsal side of the foot.
(d) Both (a) and (b)

Answer
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Hint: This is the cavity that contains gills, anus, osphradium, nephridiopores, and gonopores and it also includes the surface on which the animal creeps. This acts as a burrowing organ in some mollusks.

Complete answer:
In the body of mollusks, a visceral hump is present on the ventral side of the foot and mantle cavity.
Visceral hump is also known as visceral mass. It is present within the shell of mollusks. It carries different systems such as the digestive system, reproductive system, excretory system, and respiratory systems. Other than the ventral side of the foot the visceral hump also includes the mantle which consists of two flaps. These flaps are responsible for the secretion of the material that forms the shell in mollusks i.e., the tissue of mantle at the forward edge of the cavity secretes the shell and also protects the mantle cavity. The mantle cavity contains the gills that excrete wastes and circulate oxygen.

Additional Information:
- The upper surface of the mantle cavity also serves as a respiratory function.
- In marine species, the ciliated lining of the mantle cavity helps in creating a water current that passes posteriorly across the gill, or ctenidium, and thus the osphradium, which is assumed to be a sense organ which will detect chemical changes within the environment.
- The mantle cavity is an area for the top and foot when these organs are retracted.
- The water current sweeps across the posterior a neighborhood of the mantle cavity, where lies the nephridiopore, or opening of the kidney.
- The water current then passes anteriorly along the proper margin past the anus, through which undigested particles of food are eliminated.- Cilia on the gill play an important role in water flow through the mantle cavity and they also help some species to capture the food particles.
So, the correct answer is, ’(d) Both (a) and (b)’.

Note:
- Visceral hump is present within the shell of mollusks.
- It carries different systems such as the digestive system, reproductive system, excretory system, and respiratory systems.
- The tissues of the mantle at the forward edge of the cavity secretes the shell.
- The mantle cavity serves as a space for the head and foot when these organs are withdrawn.