Q.Name the infective stage of Plasmodium. Give any two symptoms of malaria.
Concept understanding — Malaria
Malaria is a vector-borne disease caused by the protist Plasmodium (species P. vivax, P. ovale, P. malariae, P. falciparum — only P. falciparum typically causes serious/fatal illness), transmitted by the bite of the female Anopheles mosquito.
Symptoms appear 7-15 days after an infective bite: the classical sign is a cyclic high fever with sweating and shivering, recurring every two-three days, plus vomiting, joint pain, anaemia, haemoglobinuria, hepatomegaly and, in severe P. falciparum cases, cerebral malaria.
Transmission/life cycle: a bite injects sporozoites, which undergo asexual schizogony in the liver and then red blood cells (producing merozoites that rupture RBCs, causing the fever cycle); some merozoites become gametocytes, which, if taken up by a mosquito, fertilise in its gut to form a zygote -> oocyst, which by meiotic sporogony produces fresh sporozoites in the salivary glands, ready to infect the next host.
Diagnosed via blood-smear microscopy or nucleic-acid tests; treated with Artemisinin-based Combination Therapies (ACTs) and quinine; prevented by mosquito nets/repellents, insecticide spraying, draining stagnant water, and biological control with Gambusia fish.
The infective stage of Plasmodium is the sporozoite; malaria's symptoms include cyclic high fever with chills/shivering and headache.
Infective stage: sporozoite. Two symptoms: cyclic high fever with chills and shivering, and headache
The infective stage of Plasmodium is the sporozoite; malaria's symptoms include cyclic high fever with chills/shivering and headache.
Step 1. The infective stage that an infected female Anopheles mosquito injects into a human during a bite is the sporozoite, which then travels to the liver to begin the infection.
Step 2. Among malaria's symptoms, the classical sign is a cyclic occurrence of high fever followed by sweating and sudden shivering, recurring every two to three days.
Step 3. Other early symptoms include headache and chills, which can initially be hard to recognise as malaria.
Infective stage: sporozoite. Two symptoms: cyclic high fever with chills and shivering, and headache
Separate the two parts of the question: identify Plasmodium's infective stage, then name two symptoms from the signs-and-symptoms list.
- Naming the merozoite or gametocyte (later stages within the human host) instead of the sporozoite, which is specifically the stage injected by the mosquito and therefore the infective stage.
- Giving only general 'fever' without noting its distinctive cyclic (recurring, every two-three days) pattern, which is the classical diagnostic clue for malaria.
- CBSE 2026Set EG1 markQ.Malaria disease is transmitted by which organism?
›Reveal solutionSolution
Malaria is spread by the bite of an infected female Anopheles mosquito (vector of Plasmodium).
Malaria is caused by the protozoan parasite Plasmodium (species such as P. vivax, P. falciparum, P. malariae, P. ovale). The parasite is not transmitted directly between people; it needs a vector. When a female Anopheles mosquito bites an infected person it takes up the parasite, which multiplies in the mosquito, and it then injects the infective stage (sporozoites) into the next healthy person during a blood meal. Thus the mosquito is both a vector and the definitive host. (Only females bite because they need a blood meal to develop their eggs.)
✓Final answerThe female Anopheles mosquito — it transmits the Plasmodium parasite that causes malaria.
- CBSE 2026Set A1 markMCQQ.What type of organism is the pathogen responsible for malaria?(a) Virus(b) Bacteria(c) Protozoa(d) Nematode
›Reveal solutionSolution
Malaria is caused by a protozoan, Plasmodium (transmitted by the female Anopheles mosquito).
Malaria is caused by Plasmodium (species such as P. vivax, P. falciparum), which is a protozoan parasite. It is transmitted from person to person through the bite of an infected female Anopheles mosquito. The pathogen itself is a protozoan — not a virus, bacterium or nematode.
✓Final answer(C) Protozoa.
- CBSE 2026Set ANNUAL1 markMCQQ.Which species of plasmodium causes most severe and fatal malignant malaria?(a) P. Vivax(b) P. Malaria(c) P. Falciparum(d) P. Ovale
›Reveal solutionSolution
Of the human malaria parasites, Plasmodium falciparum causes malignant tertian malaria, the deadliest form.
Several Plasmodium species infect humans - P. vivax, P. malariae, P. ovale and P. falciparum - transmitted by the female Anopheles mosquito. Among these, P. falciparum causes the most severe, malignant form of malaria, which can be fatal if untreated, due to its ability to infect red blood cells of all ages and cause complications such as cerebral malaria.
✓Final answer(c) P. Falciparum.
- CBSE 2025Set 57/4/11 markMCQQ.Assertion (A) : A person infected with malaria suffers from chill and high fever, recurring every three or four days. Reason (R) : The parasite attacks the RBC resulting in their rupture and release of haemozoin.
›Reveal solutionSolution
The characteristic recurring chills and high fever in malaria are indeed caused by the synchronous rupture of red blood cells and the release of toxins like haemozoin by the Plasmodium parasite, making both the assertion and reason correct, with the reason explaining the assertion.
Malaria is a disease whose symptoms are directly tied to the life cycle of the Plasmodium parasite within the human body. Understanding this cycle, particularly the phase involving red blood cells, is key to grasping why the symptoms manifest as they do. The recurrent fever and chills are not random; they are a precise biological event.
When an infected Anopheles mosquito bites a human, it injects sporozoites. These travel to the liver, multiply, and then release merozoites into the bloodstream. It is when these merozoites invade red blood cells (RBCs) that the symptomatic phase of malaria begins. Inside the RBCs, the parasites grow and multiply, consuming hemoglobin. This process culminates in the synchronized rupture of a large number of infected RBCs, releasing new parasites and metabolic byproducts, including haemozoin, into the bloodstream. This sudden release triggers a strong inflammatory response from the host's immune system, leading to the characteristic chills and high fever. The periodicity of these symptoms directly reflects the duration of the asexual reproductive cycle of the parasite within the RBCs.
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Analyze Assertion (A): "A person infected with malaria suffers from chill and high fever, recurring every three or four days."
- This statement is factually correct. The clinical presentation of malaria typically involves bouts of chills followed by high fever. The recurrence pattern is characteristic: for example, Plasmodium vivax and P. ovale cause tertian malaria, where fever recurs every 48 hours (on the third day), while Plasmodium malariae causes quartan malaria, with fever recurring every 72 hours (on the fourth day). P. falciparum can also exhibit a tertian pattern or more irregular fevers. Thus, the assertion accurately describes the disease's symptoms.
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Analyze Reason (R): "The parasite attacks the RBC resulting in their rupture and release of haemozoin."
- This statement is also factually correct. After invading red blood cells, the Plasmodium parasite multiplies asexually. During its growth, it digests hemoglobin, converting the heme portion into a crystalline pigment called haemozoin. This haemozoin, along with other parasitic waste products and new merozoites, is released into the bloodstream when the infected RBCs rupture. This rupture is a critical event in the parasite's life cycle and the pathogenesis of malaria.
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Determine if Reason (R) correctly explains Assertion (A):
- The events described in Reason (R) are the direct cause of the symptoms mentioned in Assertion (A). The synchronized rupture of a large number of infected red blood cells releases a flood of merozoites, haemozoin, and other parasitic toxins into the bloodstream. These substances act as pyrogens, stimulating the host's immune system to release cytokines, which in turn trigger the body's thermoregulatory centers, leading to the sudden onset of chills and a rapid rise in body temperature (fever). The periodicity of these fever episodes directly corresponds to the synchronous asexual reproductive cycle of the parasite within the red blood cells. Therefore, the Reason provides a complete and accurate explanation for the Assertion.
✓Final answerBoth Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation for Assertion (A).
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- CBSE 2025Set F1 markMCQQ.Which of the following is a source of quinine?(a) Canabis(b) Cinchona(c) Poppy(d) Eucalyptus
›Reveal solutionSolution
Quinine, used against malaria, comes from the bark of Cinchona.
Quinine is an alkaloid extracted from the bark of the Cinchona tree; it has long been used as an anti-malarial drug (acting against the Plasmodium parasite). Cannabis yields drugs of abuse (cannabinoids), Papaver (poppy) yields opium/morphine, and Eucalyptus yields aromatic oil — none of these is the source of quinine.
✓Final answer(B) Cinchona.
- CBSE 2025Set F1 markMCQQ.Which of the following is a pathogen of malaria?(a) Plasmodium(b) Wuchereria(c) Sacromyces(d) Puccinia
›Reveal solutionSolution
Malaria is caused by Plasmodium.
Malaria is caused by the protozoan parasite of the genus Plasmodium (species such as P. vivax, P. malariae and the most serious P. falciparum). The parasite is transmitted to humans through the bite of an infected female Anopheles mosquito, which acts as the vector.
Checking the other options: Wuchereria bancrofti causes filariasis (elephantiasis); Saccharomyces is a yeast (fermentation, not a human pathogen here); Puccinia is a rust fungus that infects plants (wheat rust).
✓Final answer(a) Plasmodium.
- CBSE 2025Set A1 markQ.Write True / False: Malaria disease is caused by Plasmodium in human.
›Reveal solutionSolution
The statement is True: malaria is caused by Plasmodium, a protozoan parasite.
Malaria is caused by species of the protozoan genus Plasmodium (e.g., P. vivax, P. falciparum), transmitted to humans through the bite of an infected female Anopheles mosquito. The parasite multiplies within red blood cells, and its periodic release causes the characteristic recurring high fever with chills that is typical of malaria. This is a correctly stated fact.
✓Final answerTrue.
- CBSE 2024Set ANNUAL1 markQ.Give the scientific name of the protozoa which causes Malignant Malaria disease.
›Reveal solutionSolution
Malignant (the most severe form of) malaria is caused by the protozoan Plasmodium falciparum.
Malaria is caused by protozoan parasites of the genus Plasmodium, transmitted by the bite of an infected female Anopheles mosquito.
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Plasmodium falciparum causes malignant tertian malaria, the most severe and potentially fatal form, which can lead to complications like cerebral malaria.
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(By contrast, Plasmodium vivax causes the milder benign tertian malaria.)
✓Final answerThe scientific name of the protozoan causing Malignant Tertian Malaria is Plasmodium falciparum.
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- CBSE 2023Set ANNUAL1 markMCQQ.Which of the following parasites is the causative organism of malaria?(a) Ascaris(b) Plasmodium(c) Salmonella(d) Rhino virus
›Reveal solutionSolution
Malaria is a protozoan disease caused by Plasmodium, spread by the bite of an infected female Anopheles mosquito.
Among the options: Ascaris is a roundworm (causes ascariasis, a helminthic disease); Salmonella typhi is a bacterium (causes typhoid); Rhinovirus causes the common cold. Plasmodium is a unicellular protozoan parasite that completes part of its life cycle in the human liver and red blood cells (causing the characteristic recurring fever due to RBC rupture releasing a toxic substance, haemozoin) and part in the female Anopheles mosquito, which acts as the vector/definitive host.
✓Final answer(b) Plasmodium.
- CBSE 2021Set OC_ZOOLOGY1 markMCQQ.Malaria is caused by(a) Entamoeba sp.(b) Ascaris sp.(c) Plasmodium sp.(d) Wuchereria sp.
›Reveal solutionSolution
Malaria is a protozoan disease caused by Plasmodium species, transmitted by the female Anopheles mosquito vector.
The causative agent
Malaria in humans is caused by species of the protozoan genus Plasmodium — chiefly P. vivax and the more severe P. falciparum, and also P. malariae and P. ovale. The parasite is injected into the human bloodstream as sporozoites when an infected female Anopheles mosquito bites, multiplies inside liver cells and then red blood cells, and the periodic rupture of infected RBCs (releasing a toxic substance, haemozoin) causes the classic recurring high fever with chills.
Ruling out the other organisms
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Entamoeba histolytica — causes amoebiasis (amoebic dysentery), a protozoan disease of the intestine, not malaria.
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Ascaris lumbricoides — a roundworm (helminth) causing ascariasis, an intestinal worm infection.
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Wuchereria (W. bancrofti / W. malayi) — filarial worms causing lymphatic filariasis (elephantiasis), transmitted by Culex mosquitoes, not Anopheles.
✓Final answerMalaria is caused by Plasmodium sp.
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- CBSE 2018Set ANNUAL1 markQ.Haemozoin and histamine are chemical substances released in the human body. Differentiate between the two.
›Reveal solutionSolution
Haemozoin and histamine are both released inside the body but from very different causes and cell types — haemozoin comes from a malaria parasite destroying red blood cells, while histamine comes from the body's own immune (mast) cells during an allergic response.
Haemozoin:
- Released when Plasmodium (the malaria-causing parasite) multiplies inside RBCs and ruptures them at the end of its erythrocytic schizogonic cycle.
- Haemozoin is a toxic, dark pigment (from digested haemoglobin) that is released along with other toxic substances into the blood when RBCs burst.
- Its release coincides with the recurring high fever and chills of malaria (occurring every 48 or 72 hours depending on the Plasmodium species).
Histamine:
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Released by mast cells (and basophils) as part of an allergic/immune (hypersensitivity) reaction, when an allergen binds to IgE antibodies already attached to these cells.
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Histamine causes the typical symptoms of allergy — sneezing, watery eyes, running nose, bronchial constriction/breathlessness, itching, swelling.
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It is part of the body's own (mis-directed) immune response, unrelated to any parasite.
✓Final answerHaemozoin = a pigment from digested haemoglobin, released when malaria parasites (Plasmodium) rupture RBCs, causing the fever of malaria. Histamine = a chemical released by mast cells/basophils during an allergic reaction, causing symptoms of allergy.
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