Question

How many ganglia lies in thorax and in the abdomen of cockroach? (a) 3 and 6 (b) 6 and 3 (c) 2 and 1 (d) 1 and 2

Short answer

There are 3 ganglia in the thorax and 6 ganglia in the abdomen of a cockroach. So, option (a) 3 and 6 is correct.

Step-by-step solution

Recall Cockroach Anatomy

Cockroaches, part of the Insecta class, have a sophisticated nervous system with a series of ganglia - clusters of nerve cells. The insect's body is divided into the head, thorax, and abdomen. Each of these sections contains different numbers of ganglia.

Identify Thoracic Ganglia

The thorax of a cockroach, which is its middle section, just behind the head, contains three segments: the prothorax, mesothorax, and metathorax. Each of these thoracic segments houses one ganglion each. Thus, there are three ganglia in the thorax of a cockroach.

Identify Abdominal Ganglia

The abdomen of a cockroach, which is the largest and final section of its body, has ten segments. But, not every segment contains a ganglion. There are six ganglia within the abdomen of a cockroach.

Key concepts

Ganglia in Insects

Understanding the nervous system of insects, particularly the existence and function of ganglia, is crucial for students of biology. Insects, like cockroaches, have a segmented nervous system composed of clustered nerve cells known as ganglia. These clusters act as relay points, processing sensory input and directing motor output to the various parts of the insect's body, allowing for complex and coordinated movements.

In a closer look, each segment of an insect's body typically has a pair of ganglia. In the thorax, responsible for locomotion due to the attached legs and wings, ganglia are especially important for coordinating walking, flying, and other reflex actions. The simplicity yet effectiveness of the insect's nervous system, demonstrated through the dispersion of ganglia, is a fascinating topic in entomology and provides a window into the evolutionary biology of organisms with less complex nervous systems compared to humans.

Cockroach Anatomy

The anatomy of a cockroach is an interesting point of study when exploring invertebrate biology and physiology. These resilient creatures are equipped with anatomical features that allow them to survive in various environments. The body of a cockroach is divided into three primary sections: the head, the thorax, and the abdomen. The head carries sensors and mouthparts, while the thorax is connected to the legs and wings, making it the main center for movement.

As previously mentioned, within the thorax lie three ganglia, one in each of the segments: prothorax, mesothorax, and metathorax. These ganglia enable the cockroach to perform rapid and coordinated movements. In the abdomen, despite having ten segments, only six contain ganglia. These ganglia are crucial for controlling the functions of the abdomen, including reproduction, digestion, and excretion. This foundational knowledge of a cockroach's internal structure is not only fascinating for students of biology but also has practical implications in understanding how to manage these often-unwelcome house guests.

Biology for NEET

The study of biology for the National Eligibility cum Entrance Test (NEET) demands a strong grasp of both fundamental concepts and intricate details of various organisms, including human anatomy, plant physiology, and the physiology of other animals such as insects. In particular, topics like the nervous system of insects, including the distribution of ganglia, are critical for aspiring students.

NEET aspirants must be thorough with animal anatomy, and understanding the anatomy of a common insect like the cockroach can serve as a model for learning the basic principles of nervous systems in animals. The detailed study of cockroach anatomy, including its segregated nervous system, helps reinforce the concepts of biological organization and function that are applicable across various species. For success in competitive exams like NEET, students must integrate this knowledge with a broader understanding of how living organisms, from the simplest to the most complex, maintain homeostasis and interact with their environments.