Question

Assertion: Excretion in cockroach occurs by Malpighian tubules
Reason: Each Malpighian tubule is lined by non- ciliated cells.
A) Both assertion and reason are correct and reason is the correct explanation for assertion
B) Both assertion and reasons are correct but reason is not the correct explanation for assertion
C) Assertion is correct but reason is incorrect
D) Both assertion and reason are incorrect.

Answer 1

Hint: Cockroaches are nocturnal animals that have become part of the life of humans. They are uricotelic which means they secretes uric acid as the by - waste out from their body. These animals generally have specialized structures to excrete waste out of the body.

Complete answer:
Cockroaches are generally brown or black body animals that are included in class Insecta of Phylum Arthropods. Their body colour ranges from bright yellow to red and green especially in the tropical regions. Cockroaches generally range from 0.6 inches to 3 inches. Their body is divided into long antennae, legs and flat extension of the upper body wall that generally conceals the head of them. These animals are generally nocturnal omnivores that live in damp places all over the world. One can easily find them residing in human’s homes and thus are serious pests and vectors that can cause severe diseases in humans.

The body of the cockroach is distinct into 3 regions, i.e., head, thorax and the abdomen. Their entire body is covered by a hard chitinous exoskeleton. The exoskeleton of them contains a hardened plate which is called sclerites and is present in each section of the body. These are joined to each other by a thin and flexible articular membrane.

There are rings of 100 - 150 yellow colored thin filamentous Malpighian tubules at the junction of midgut and the hindgut. These are the excretory organs in cockroaches which are responsible for and helpful in removal of excretory products from hemolymph. These tubules arise in six groups that hang freely in the haemocoel without any external opening into it.

The tubule of these cockroaches are generally lined by glandular and ciliated cells. The nitrogenous waste products are absorbed by them which later gets converted into uric acid and is excreted out through the hindgut. Therefore, this insect is called uricotelic. Apart from Malpighian tubule his fat body, nephrocytes and urecose glands also help in excretion.

The assertion is a correct statement about the cockroaches but the reason for the assertion is incorrect, so option C is the correct answer.


Note: Periplaneta americana is the adult’s most common species of cockroaches that are about 34- 53 mm long with wings that extend beyond the tip of the abdomen in males. Many of these are of no economic importance. There are very few species that live in and around human habitat. They are called pests because they destroy food and contaminate it with their excreta. Several bacterial diseases can be transmitted through the contaminated food material that we have taken in.