Question

Circulatory system of cockroach is present
(A) On the dorsal side with a 13 unit heart in the abdomen.
(B) On the dorsal side with 10 abdominal and 3 thoracic units of heart.
(C) On the ventral side with a 13 unit heart in the abdomen.
(D) On the ventral side with 10 abdominal and 3 thoracic units of heart.

Answer 1

The cockroaches have an open circulatory system. The heart of the cockroach is arranged mid-dorsally. It contains 13 segmented chambers which are of the funnel-shaped.circulatory system and are divided into 3 parts i.e head, abdomen, and the thorax.

Complete answer:
In cockroaches, there are 13 segments in the heart out of which 10 chambers or units are arranged dorsally, and the rest 3 units or chambers are in the thoracic region. The blood of the cockroach is colorless and is known as hemolymph.
The Periplaneta americana is the largest species of cockroach which is commonly found around us.
Hemolymph contains blood cells which are Hemocytes, Plasmocytes, and Coagulocytes. The blood does not flow through the vessels. They come in direct contact with the tissue. The plasma of hemolymph i.e blood of cockroach contains many organic compounds, ions, enzymes, and a few more required chemicals or compounds. The cockroach has a chitinous body i.e it’s whole body is covered with a chitinous exoskeleton of brown color. The abdomen is divisible into 10 segments, each of which is surrounded by chitinous exoskeleton plates called sclerites.
As you know cockroaches have 13 chambers, the first chamber of the heart opens into the aorta. Oxygenated blood enters into each chamber through an Ostia. The backflow of blood in Ostia is guarded by auricular valves.
So, the correct answer is ‘(B) On the dorsal side with 10 abdominal and 3 thoracic units of heart’.

Note: The heart is the key organ for blood circulation. It is a muscular organ and helps in pumping blood. Cockroaches have a multi-chambered heart which has many chambers present in it. The heart of cockroaches is more resistant to heart failure than the human heart. Alary muscles are found in the pericardial wall of cockroaches and other insects.