Identify the incorrect statements.
(A) Gametocytes of Plasmodium develop in the RBCs.
(B) Ascariasis pathogens are transmitted to a healthy person through the bite by the female mosquito vectors.
(C) Entamoeba histolitica is a helminth parasite in the small intestine of human which causes amoebiasis.
(D) Malarial parasite reproduces asexually in the gut of mosquito.
(E) Filarial worms reside in the lymphatic vessels of the lower limbs.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (B), (C) and (D) only
(A) Gametocytes of Plasmodium develop in the RBCs. — True. In the human body, the parasites multiply in the liver cells and then in the red blood cells. Some of them develop into male and female gametocytes inside the RBCs; these are taken up by the mosquito.
(B) Ascariasis pathogens are transmitted to a healthy person through the bite by the female mosquito vectors. — False. Ascaris spreads through food and water contaminated with its eggs, not through a mosquito. The line about the bite of the female mosquito is NCERT’s line on the filarial worm, put here against ascariasis.
(C) Entamoeba histolitica is a helminth parasite in the small intestine of human which causes amoebiasis. — False. Entamoeba histolytica is a protozoan, not a helminth (worm), and it lives in the large intestine. Both parts of the statement are wrong.
(D) Malarial parasite reproduces asexually in the gut of mosquito. — False. Plasmodium reproduces asexually in the human host, in the liver cells and the RBCs. In the mosquito’s gut the gametes fuse (fertilisation), which is the sexual stage, and sporozoites then develop and move to the salivary glands.
(E) Filarial worms reside in the lymphatic vessels of the lower limbs. — True. This is where Wuchereria lives, and the swelling it causes there is elephantiasis.
NCERT Extract:
Common Diseases in Humans – “… Let us take a glance at the life cycle of Plasmodium (Figure 7.1). Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. … Entamoeba histolytica is a protozoan parasite in the large intestine of human which causes amoebiasis (amoebic dysentery). … Ascaris, the common round worm and Wuchereria, the filarial worm, are some of the helminths which are known to be pathogenic to man. Ascaris, an intestinal parasite causes ascariasis. Symptoms of these disease include internal bleeding, muscular pain, fever, anemia and blockage of the intestinal passage. The eggs of the parasite are excreted along with the faeces of infected persons which contaminate soil, water, plants, etc. A healthy person acquires this infection through contaminated water, vegetables, fruits, etc. Wuchereria (W. bancrofti and W. malayi), the filarial worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and the disease is called elephantiasis or filariasis (Figure 7.2). The genital organs are also often affected, resulting in gross deformities. The pathogens are transmitted to a healthy person through the bite by the female mosquito vectors.”