Question

Read the given paragraph. "It is lined by glandular and ciliated cells. It absorbs nitrogenous waste products from haemocoel and convert them into uric acid which is excreted out though the hindgut." Which of the following structures of cockroach is referred here? (a) Trachea (b) Hepatic caecum (c) Tergum (d) Malpighian tubule

Short answer

The structure referred to in the paragraph is the Malpighian tubule (d).

Step-by-step solution

Identify Key Functions

Read the paragraph carefully and pinpoint the biological processes and functions mentioned. The paragraph describes cells that absorb nitrogenous waste products and convert them into uric acid, which is then excreted.

Match Functions to Biological Structures

Correlate the mentioned functions to the known structures within a cockroach. Research or recall from knowledge of cockroach anatomy which structure is responsible for absorbing waste and converting it into uric acid for excretion.

Select the Correct Option

Based on the functions of absorbing waste and converting it to uric acid, identify which of the given options is responsible for these processes. Trachea is for respiration, Hepatic caecum is associated with digestion, Tergum is part of the exoskeleton, and Malpighian tubule is involved in excretion.

Conclusion

The correct structure that matches the description of absorbing nitrogenous waste and converting it into uric acid for excretion through the hindgut is the Malpighian tubule. It is the excretory organ of a cockroach.

Key concepts

Excretion in Cockroach

Understanding how a cockroach disposes of its waste products is essential for comprehending the complexity of invertebrate physiology. Similar to other organisms, cockroaches need to eliminate nitrogenous waste to maintain homeostasis. In cockroaches, the primary system for excreting these nitrogenous compounds is through structures known as Malpighian tubules.

The Malpighian tubules, named after the Italian biologist Marcello Malpighi, are delicate, thread-like structures attached at the junction where the midgut meets the hindgut. They float freely within the body cavity and are bathed in the insect's hemolymph (a fluid analogous to blood in vertebrates). As the hemolymph circulates through the cockroach's body, it carries waste products that need to be excreted. The Malpighian tubules absorb and filter these toxins from the hemolymph.

This excretory process is a critical aspect of a cockroach's physiology and an excellent example of evolutionary adaptation, allowing these insects to thrive in diverse environments.

Nitrogenous Waste Absorption

Nitrogenous waste, primarily in the form of ammonia, is toxic for most organisms and must be converted into less harmful substances for excretion. Cockroaches and other terrestrial arthropods convert ammonia into uric acid as a means of nitrogenous waste management.

The Malpighian tubules play a central role in this process. Their highly efficient and specific absorption capabilities allow them to extract nitrogenous waste directly from the hemolymph. Inside the tubules, ammonia, along with other solutes, is converted into uric acid, which is less toxic and more soluble. This method of excretion is particularly advantageous for land-dwelling insects like cockroaches as it helps in conserving water, crucial for their survival in dry environments.

By controlling the selective absorption of ions and other organic compounds, the Malpighian tubules effectively filter out waste while keeping the necessary substances within the hemolymph, maintaining the insect's internal chemical balance.

Uric Acid Conversion

The conversion of nitrogenous waste into uric acid within the Malpighian tubules is a vital adaptation for the survival of cockroaches. Uric acid is relatively non-toxic and insoluble, allowing these insects to store waste without significant water loss or toxicity issues.

Enzymes within the Malpighian tubules catalyze the transformation of nitrogenous waste into uric acid crystals. These crystals are then combined with feces in the hindgut of the cockroach to form a semi-solid waste that is expelled from the body.

The ability to convert nitrogenous waste to uric acid is not only an efficient waste management system but also an evolutionary trait common among insects, reptiles, and birds. This process showcases the intriguingly complex nature of excretory systems across various life forms and highlights the Malpighian tubules' role in cockroach's remarkable adaptability in different ecological niches.