Plasmodium: Lower Animal - Class 11 MCQ

Plasmodium is a protozoan parasite and its life cycle is digenetic, as it completed in two hosts (human & mosquito). Fasciola hepatica (liver fluke) female lays eggs in the liver of an infected human. Immature eggs are discharged in the biliary ducts and taken out in the feces. It develops larvae called miracidia outside the host. Thus, it is also digenetic.

The red blood cells in humans lack a nucleus, mitochondria, Golgi bodies and endoplasmic reticulum which allows them to have a biconcave shape that helps in diffusion.
The absence of mitochondria, Golgi bodies and endoplasmic reticulum allows the RBCs to have more haemoglobin which helps to carry more oxygen molecules.
So, the correct answer is 'RBCs'.

The malaria parasite life cycle involves two hosts. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host . Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites.

On 20 August 1897, in Secunderabad, Ross made his landmark discovery. While dissecting the stomach tissue of an anopheline mosquito fed four days previously on a malarious patient, he found the malaria parasite and went on to prove the role of Anopheles mosquitoes in the transmission of malaria parasites in humans.

In the United States, the National Malaria Eradication Program (NMEP) was launched on 1 July 1947. This federal program with state and local participation had succeeded in eradicating malaria in the United States by 1951.
So, the correct answer is option D.

The discovery that malaria parasites developed in the liver before entering the blood stream was made by Henry Shortt and Cyril Garnham in 1948 and the final stage in the life cycle, the presence of dormant stages in the liver, was conclusively demonstrated in 1982 by Wojciech Krotoski.

Mircrogametocytes are the mother cell producing the microgametes, or male elements of sexual reproduction in sporozoan protozoans and fungi.

Malaria parasites undergo a complex series of developmental and migratory transitions within the mosquito vector, starting with ingested gametocytes transforming into gametes that fertilise to produce zygotes within the bloodmeal, which subsequently transform into motile ookinete stages that migrate from the midgut.
Oogenesis has been followed with the electron microscope in 2 strains of the malaria mosquito Anopheles gambiae, from the emergence of the adult (oocytes at leptonema) till shortly before the oocytes are ready for oviposition. After pachynema the chromosomes form a karyosphere and a fibrous capsule develops around it.
Gametocytes within a mosquito develop into sporozoites. The sporozoites are transmitted via the saliva of a feeding mosquito to the human bloodstream. From there they enter liver parenchyma cells, where they divide and form merozoites.

Exo- erythrocytic cycle: It is the second phase of asexual multiplication of plasmodium in the liver cell. It starts when crypto merozoites enter into the fresh liver cell and grow into rounded schizont. Schizont then undergoes multiple fission, to produce meta crypto merozoites.

Class of chemotherapy drugs also kills the parasite that causes malaria. Researchers in Europe have discovered that a class of chemotherapy drugs originally designed to inhibit key signaling pathways in cancer cells also kills the parasite that causes malaria.

Pre erythrocytic phase- Before a victim ever succumbs to the clinical symptoms of the disease, which present themselves in the erythrocytic stage, the clinically silent pre- erythrocytic life cycle stages, transmitted by Anopheles mosquitoes, invade the body and develop in the liver.
Exoerythrocytic stage- A stage in the life cycle of the malaria parasite found in liver cells. These do not cause symptoms.
Erythrocytic Phase- It is the first life stage of plasmodium. The next stage in malaria life cycle is the one of asexual reproduction.

Plasmodium species of malaria parasites progress through liver and blood stages before gametocytes enable sexual reproduction to occur in the mosquito midgut. Once an erythrocyte has been invaded, the parasite feeds on the hemoglobin, and this form is known as a trophozoite. The amoeboid feeds completely the component of corpuscles in the form of hemoglobin. During feeding the hemoglobin breakdown into hematin and globin. The globin is absorbed by the cell and hematin is deposited in the form of hemozoin (toxic malarial pigment). 

The amoeboid trophozoites after feeding, becomes rounded, grows in size and becomes erythrocytic schizont. Asexual multiplication takes place in schizont and forms merozoites which give pressure to the wall of weak RBC and liberated out in the form of erythrocytic merozoites.

Plasmodium falciparum is the causative agent of one type of malaria known as malignant tertian malaria in which the vector is a female mosquito of the genus Anopheles.
Pernicious malaria is caused by Plasmodium falciparum and characterized by intense malarial paroxysms that after synchronization occur every 48 hours with acute cerebral, renal, or gastrointestinal manifestations in severe cases, chiefly caused by the large number of red blood cells affected and the tendency for infected red blood.

Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood.

Sir Ronald Ross, KCB, FRS, was an Indian-born British medical doctor. On 20 August 1897, in Secunderabad, Ross made his landmark discovery. He found the malaria parasite and proved that the Anopheles mosquitoes responsible for the transmission of malaria parasites in humans while dissecting the stomach tissue of an anopheline mosquito fed four days previously on a malarious patient. Thus the correct answer is option A.

In the life cycle of malarial parasite exflagellation of microgametes occur in mosquitoes. Usually this will not occur in the peripheral blood of human beings. However, exflagellation can occur in the collected blood and may create diagnostic dilemma.

The young trophozoite is often called the ring form due to its morphology in Giemsa-stained blood smears. During the trophic period, the parasite ingests the host cytoplasm and breaks down the haemoglobin into amino acids.
So, the correct answer is option B.

When the female Anopheles sucks blood malaria individual, the gametocytes of the parasite find their way into the gut of the mosquito. So this is the infected stage of the Plasmodium falciparum in female Anopheles mosquitoes.

The life cycle of this organism is complex, with the parasite alternating between sexual reproduction in an invertebrate (mosquito) host and asexual reproduction in a vertebrate host (80). In addition to Low temperature mammals as vertebrate hosts, birds and reptiles also serve as hosts for malarial parasites.

He was awarded the Nobel Prize in 1907 in recognition of his discovery of the malaria parasite and for his overall work on protozoa as causes of diseases. He gave the proceeds of his prize to the Pasteur Institute for the creation of a laboratory devoted to tropical diseases. Laveran died in Paris on May 18, 1922.

Malaria: An infectious disease caused by protozoan parasites from the Plasmodium family that can be transmitted by the bite of the Anopheles mosquito or by a contaminated needle or transfusion. Falciparum malaria is the most deadly type.
Hence, the correct answer is Option D.

In the mosquito's gut, the gametocytes (male and female) from the infected person fuse to form the zygote, called the ookinete that penetrates the gut lining and produces an oocyst in the gut wall.
Thus, the correct answer is option (B), 'Ookinete'

Oocyst is the surviving stage as it is the highly resistant stage that may survive for a long time in the fecal material of the host or in the soil. This cyst is the infective stage for the next host in the parasite’s life cycle. It occurs in coccidian parasites (microscopic, spore-forming, single-celled parasites).

Zygote form in stomach of mosquito about 9 to 10 days after the blood meal. The process of fusion of male and female gametes is called syngamy. Syngamy is anisogamous due to the dissimilar structure of gametes. Hence, their fusion is called anisogamy.

Transmission and scanning electron microscopy were used to study the ultrastructure of the oocysts, sporocysts, and sporozoites of the VEG strain of Toxoplasma gondii and to compare the ultrastructure of sporozoites with tachyzoites (from the peritoneum of mice) and bradyzoites (from brain tissue cysts in mice). Oocysts were surrounded by a thin veil of finely reticulate material. The oocyst wall consisted of 3 layers and contained a previously unknown disc-shaped micropyle that appeared as a depression in the oocyst wall. The sporocyst contained 4 sporozoites and a residuum of lipid and amylopectin granules. The sporocyst wall was 3-layered with the innermost layer consisting of 4 curved plates held together at sutures by an interposed strip. Exposure to excysting fluid caused the interposed strip to separate from the curved plates, which curled inward releasing the sporozoites. Sporozoites had a posteriorly located nucleus and all the organelles typical for coccidian zoites. Sporozoites, tachyzoites, and bradyzoites had similar numbers of rhoptries but differed in the numbers and sizes of micronemes, dense granules, amylopectin granules, and lipid bodies.

Quinine is an anti-malarial drug. It is also an anti-arrhythmic drug. It is effective against almost all varieties of the malarial parasite. The product is obtained from the bark of the Cinchona tree. Thus, quinine adds to the economic and medicinal value to the Cinchona plant. However, nowadays many cases of quinine resistant parasites have emerged. 
So, the correct answer is 'Quinine'.

In P. malariae, within the red cell, the merozoite matures either into a uninucleate gametocyte--the sexual stage, infectious for Anopheles mosquitoes--or, over 48 to 72 hours,  into an erythrocyticstage schizont containing 10 to 36 merozoites. Rupture of the schizont releases these merozoites, which infect other red cells.

Schizogony is the asexual multiplication of schizont to produce merozoites. It occurs in human liver( liver schizogony) cell and RBC ( Erythrocytic schizogony). Nucleus of schizont divides into 12 to 24 nuclei which are arranged in circular manner in rosette stage.

Malariae schizonts have 6 to 12 merozoites with large nuclei, clustered around a mass of coarse, dark-brown pigment. Merozoites can occasionally be arranged as a rosette pattern. Schizont in a thick blood smear. Schizont in thick blood smears.