Which of these statements are incorrect?
I. Filarial worm is a dreaded parasite of human blood and lymph.
II. Cysticercus develops in adult tapeworm inside the secondary host's body.
III. Sporozoite of plasmodium infact man through liver cells first.
IV. Bed bugs transmit plague, typhoid and tuberculosis.

Question

Which of these statements are incorrect? 
I. Filarial worm is a dreaded parasite of human blood and lymph. 
II. Cysticercus develops in adult tapeworm inside the secondary host's body. 
III. Sporozoite of plasmodium infact man through liver cells first. 
IV. Bed bugs transmit plague, typhoid and tuberculosis.

Accepted Answer

The correct option is 3: II and IV

The correct option is **3 (II and IV)** because it correctly identifies the two biologically inaccurate statements among the four choices. The question asks us to select the statements that are *incorrect*. Statement II and Statement IV contain factual errors regarding parasite life cycles and disease transmission, respectively. Therefore, the option that groups these two incorrect statements together is the correct answer. The key to solving this question is a precise understanding of the life cycles and vector relationships of these parasites and pests.

The incorrect option is 1: I and III

This option is incorrect because both statements I and III are factually **correct** biological statements. Statement I correctly describes the filarial worm (*Wuchereria bancrofti*), which is a nematode parasite inhabiting the lymphatic system and blood of humans, causing lymphatic filariasis. Statement III is also correct, as the infectious stage of the malaria parasite (*Plasmodium*), the sporozoite, is injected by the mosquito and must first travel to and infect the liver cells (hepatocytes) before entering the bloodstream and causing symptoms. Since the question asks for the *incorrect* statements, a choice listing two correct statements must be wrong.

The incorrect option is 2: I and II

This option is incorrect because it includes statement I, which is a factually **correct** biological statement. While statement II is indeed incorrect (Cysticercus is the larval stage that develops in the secondary host's tissues from ingested eggs, not inside the adult tapeworm), the inclusion of statement I makes this option an invalid answer to the question asking for *incorrect* statements. The filarial worm is definitively a major human parasite, primarily infecting the lymphatic system. Since only the combination of two incorrect statements is the required answer, this pairing is flawed.

The incorrect option is 4: III and IV

This option is incorrect because it includes statement III, which is a factually **correct** biological statement. The statement correctly identifies the initial target of the *Plasmodium* sporozoite infection in humans as the liver cells, which is the necessary step before the parasite can enter the erythrocyte cycle. Although statement IV is correctly identified as an incorrect statement (bed bugs are not vectors for the listed diseases), the inclusion of the correct statement III means this pair does not exclusively contain the incorrect biological facts. Therefore, this option cannot be the answer to a question asking for the collection of incorrect statements.