Problem 74 - Objective Biology for NEET

Question

Flame cells helps in excretion and osmoregulation in (a) Earthworm (b) Hookworm (c) Roundworm (d) Tapeworm

Step-by-Step Solution

Answer

The correct answer is (d) Tapeworm. Tapeworms use flame cells for their excretion and osmoregulation.

Step 1: Understand Flame cells

Flame cells serve as the primary organ of excretory system in certain invertebrate organisms. They function in osmoregulation. These cells are also part of a simple kidney-like system that gets rid of the wastes produced by the cells' metabolism.

Step 2: Identify types of worms

Earthworms have a different set of structures for excretion, whereas roundworms and hookworms excrete waste directly through their body wall. On the contrary, tapeworms use flame cells for their excretion and osmoregulation.

Step 3: Choosing the correct answer

From the above step (Step 2), it can be seen that out of the earthworm, hookworm, roundworm and tapeworm, it is the tapeworm that utilizes flame cells for excretion and osmoregulation. Thus, the correct answer is (d) tapeworm.

Key Concepts

Excretion in Invertebrates

Invertebrates come in many shapes and sizes, ranging from tiny microscopic organisms to larger creatures like earthworms and jellyfish. Despite their diversity, all invertebrates share a common need to remove waste products from their bodies. Excretion is the process by which these pesky byproducts of metabolism are expelled. This is crucial for survival as waste buildup can be toxic.

Unlike vertebrates, whose excretory systems often comprise complex organs like kidneys, invertebrates utilize simpler structures. Many invertebrates rely on specialized cells or tubes to conduct excretion. These systems are not only involved in the removal of waste but also play a role in maintaining the internal chemical balance of the organism. This is where osmoregulation comes into play.

• In earthworms, the nephridia act as the main excretory organ.
• For simpler organisms like flatworms and some annelids, special structures such as flame cells are employed.
• Flame cells are tiny, bulb-like structures that filter waste products from the creature's body fluids and release them to the outside environment.

Osmoregulation

Osmoregulation is the process by which an organism regulates the water and ionic balance within its body. This is vital for maintaining cellular function and integrity. In marine environments or watery habitats, invertebrates constantly face challenges in maintaining this delicate equilibrium due to the continuous movement of water and salts across their membranes.

In simple terms, osmoregulation ensures that an organism neither dries out nor floods with too much water. Many invertebrates have adapted specialized cells for this role.

• Flame cells, found in flatworms, not only help with excretion but are also integral to osmoregulation.
• These cells draw in excess fluids and salts, processing them, and ultimately expelling the excess while retaining necessary elements.
• In this way, flame cells act like primitive kidneys, keeping the internal environment of the invertebrate stable.

By performing their dual role, these cells allow the organism to thrive in variable habitats.

Tapeworm Excretion

Tapeworms are parasitic flatworms that live in the intestines of their hosts, absorbing nutrients directly from the host's digested food. Shelter inside a nutrient-rich environment, tapeworms have evolved unique adaptations for excretion and osmoregulation.

Flame cells play a critical role in their biology.

• These structures help in eliminating metabolic waste and also assist in maintaining an osmotic balance despite living in the host’s gut.
• Because tapeworms are parasitic, they don’t have a digestive tract and thus, they discharge waste differently than other invertebrates.
• The waste generated is transferred out of their body through excretory canals, ensuring that these parasites don't become clogged with their own waste products.

The combination of these processes allows tapeworms to continue their parasitic lifestyle efficiently, demonstrating the extraordinary adaptations of invertebrate excretory systems.