Cockroach (Only in NEET, Not NCERT) - NEET Biology Class 11 Free MCQ Test

Insects including cockroach excrete nitrogenous waste in the form of soluble potassium urate which is liberated into the haemolymph and taken up by the cells lining the Malpighian tubules. The tubules facilitate the absorption of urate by stirring up the blood. In the cells of the tubule the potassium urate reacts with water and carbon dioxide(from respiration) to form potassium hydrogen carbonate and uric acid. The former is absorbed back into the blood, but the later is excreted.

The abdomen in a male and female cockroach is made up of 10 segments. The 7th, 8th and 9th sterna form a genital pouch in females. In males, the genital pouch is present at the hind end of the abdomen. The male cockroach has thread-like anal styles, which are missing in the female cockroach.

The heart of the cockroach is elongated, thick, muscular, tubular and 13-chambered. It lies in the pericardial sinus of the hemocoel. Each chamber of the heart receives oxygenated blood from the dorsal sinus through one pair of slit-like openings called ostia. The heart contracts in a posteroanterior direction and the blood also flows posteroanterior. The alary muscles are responsible for the circulation of blood.

- Anal cerci are a pair of appendages at the end of the abdomen, arising from near the 10th segment of the body of a cockroach. These are present in both males and females. Anal cerci are important sense organs of the organism as they are wind sensitive and detect vibrations.

- The abdomen is broader in female than in the male. In male in addition to cerci, the 9th sternum bears a short unjointed anal stylus, which is absent in females.

• A (Collateral gland): The collateral glands in female cockroaches are responsible for secreting a fluid that forms the wall of the ootheca (egg case). The function is to help in the formation of the protective outer casing around the fertilized eggs.

• B (Spermatheca): The spermatheca is an organ in female cockroaches that stores sperm received during mating. It allows for sperm storage to fertilize eggs later, making it crucial for reproduction.

• Option A:
  A − Conglobate gland − Converting of sperm
  B − Spermatheca − Storage of sperm
  This option is incorrect because A should refer to the Spermatheca, and B is not the conglobate gland.

• Option B:
  A − Phallomere − Covering around egg
  B − Titillator − Opening of spermatophore
  This option is incorrect because the phallomere and titillator are structures involved in mating and are not present in this diagram.

• Option C:
  A − Vestibule − Place to store fertilized eggs
  B − Spermatophore − Storage of sperms
  This option is incorrect because A refers to the Spermatheca (not vestibule), and B is not the spermatophore.

• Option D:
  A − Collateral gland − From the wall of ootheca
  B − Spermatheca − Storage of sperms in female
  This option is correct because A refers to the Spermatheca (storage of sperm), and B refers to the Collateral gland (which contributes to the wall of the ootheca).

Final Answer:

The diagram supports Option D:

A − Collateral gland − From the wall of ootheca
B − Spermatheca − Storage of sperms in female

A (Ootheca size): The ootheca of a cockroach is about 8 mm long, not 3 mm.

B (Development type): The development of P. americana (American cockroach) is Paurometabolous, which means it undergoes gradual development through a nymphal stage.

C (Brain and nervous system): The brain of a cockroach is represented by the supra-oesophageal ganglion. It supplies nerves to the compound eyes and antennae.

D (Respiratory system): The respiratory system of a cockroach consists of spiracles that open through 10 pairs of small holes located on the lateral side of the body.

Thus, Option D correctly fills all the blanks.

Option A: This is correct. The haemocoel of a cockroach contains haemolymph, which consists of colourless plasma and haemocytes (blood cells), as cockroaches lack pigments like hemoglobin.

Option B: This is incorrect. The cockroach’s nervous system consists of segmentally arranged ganglia, with three ganglia in the thorax (one per segment: prothorax, mesothorax, metathorax) and six ganglia in the abdomen (not nine), located in the 1st, 2nd, 3rd, 4th, 5th, and 7th segments (the 6th and 7th ganglia are fused).

Option C: This is correct. In male cockroaches, the mushroom gland (or utricular gland) is a reproductive accessory gland located in the 6th–7th abdominal segments, secreting substances for spermatophore formation.

Option D: This is correct. The proventriculus (gizzard) in the cockroach’s alimentary canal has an outer layer of thick circular muscles for grinding food and an inner cuticle layer with six chitinous teeth for mastication.