Biology · Human Health and Diseases · NEET
The sporozoite is the infectious stage that enters the human body. It is injected when an infected female Anopheles mosquito bites you. Do not confuse it with gametocytes (taken up by the mosquito from human blood) or trophozoites (a feeding stage inside cells). NEET asks this exact fact directly, so remember: sporozoite = the stage that goes IN.
Haemozoin is a toxic substance released when infected red blood cells (RBCs) rupture. This toxin is responsible for the chill and high fever that comes back every three to four days in malaria. NEET has matched 'Haemozoin' with 'Plasmodium' in match-the-column questions, so link haemozoin only to the malaria parasite, not to any virus or bacterium.
In humans: (1) female Anopheles mosquito injects sporozoites, (2) sporozoites reach the liver through blood, (3) parasites multiply asexually in liver cells and burst them, (4) parasites then multiply asexually in RBCs and burst them (releasing haemozoin), (5) gametocytes develop in RBCs. Key rule: liver stage comes BEFORE the RBC stage, and gametocytes form LAST in humans.
Only the female Anopheles mosquito spreads malaria. The female needs a blood meal to reproduce, so she bites humans and transfers sporozoites. Male mosquitoes feed on plant nectar and do not spread malaria. NEET options often trap you with 'male Anopheles' or 'Culex' or 'Aedes' (Aedes spreads dengue, not malaria).
Fertilization (the sexual stage) takes place in the mosquito's gut, not in the human body. Inside humans, Plasmodium only multiplies asexually (in liver cells and RBCs). The gametocytes are picked up by the mosquito during a blood meal, and then fertilization and formation of sporozoites happen in the mosquito. So the mosquito is the definitive host.
Plasmodium falciparum causes malignant malaria, the most serious and even fatal form. Other species are P. vivax and P. malariae. NEET may ask which species is 'most serious' or 'fatal' — the answer is P. falciparum.
The infectious stage of Plasmodium that enters the human body is:
Match List I with List II: A. Common cold, B. Haemozoin, C. Widal test, D. Allergy — I. Plasmodium, II. Typhoid, III. Rhinoviruses, IV. Dust mites.
Arrange the stages of the Plasmodium life cycle in order: A. Parasites reproduce asexually in RBCs, bursting the cells. B. Parasites reproduce asexually in liver cells, bursting the cells and releasing into blood. C. Gametocytes develop in RBCs. D. Sporozoites reach the liver through the blood. E. Female mosquito injects sporozoites into humans during bite.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Malaria is caused by the protozoan Plasmodium. Different species cause different types: P. vivax, P. malariae and P. falciparum. P. falciparum causes the most serious (malignant) malaria.
The vector is the female Anopheles mosquito. It transfers the parasite from one human to another. Controlling mosquitoes (nets, removing stagnant water, Gambusia fish that eat larvae) is the main way to prevent malaria.
The recurring chill and high fever is caused by haemozoin, a toxin released when infected RBCs burst together in cycles. Because the parasites burst RBCs at regular intervals, the fever returns every three to four days.
Plasmodium is a protozoan (a single-celled eukaryote), not a bacterium. This is a common NEET match-the-column trap: malaria = protozoan, typhoid = bacterium, ringworm = fungus, filariasis = worm.
In the human, Plasmodium only multiplies asexually (in liver cells and RBCs), so the human is the intermediate host. In the mosquito, the sexual stage and fertilization occur, so the female Anopheles mosquito is the definitive host.
