Question

7. Inside an earthworm where can you find the gregarines. What is the function of this organ?

8. Young trophozoites seem to have cilia which they shed later. What are these tails?

9. What is the best way this organism is transmitted from one organism to another?

10. The gametocytes are __________________ and sporozoites are ______________ (haploid diploid)

11. Who are the hosts for plasmodium and Trypanosoma gambiense?

12. Discuss the life cycle of the malarial parasite.

Answer 1

Q.7

In the seminal vesicles of earthworm we can find Gregarines

GREGARINES comes under group of Apocomplexan protozoan parasites,which are heterogeneous group comprising of 1600 species. Mature form consist of large and extracellular parasites inhabiting invertebrates like annelids, arthropods and molluscs.

The presence of these parasites is recorded especially in digestive tracts of larvae and adults, Malpighian tubules, fat bodies and eggs. In the reproductive system of insects, gregarines were reported only in accessory glands and spermathecae of females.

8. The cilia are present in young trophozoites and may be seen slowly rotating, but after prolonged encystment, the cilia disappear. Trophozoites of B. coli measures approximately 50-100μm in length but have been known to attain lengths of up to 200 μm. It is oval in shape and covered in short cilia.

9.By ingestion of spores, transmission from one organism to other

10.Gametocytes are haploid,having single set of chromosomes

Sporocytes are diploid,having a double set of chromosomes.

11.)Humans are the hosts for both malarial plasmodium and Trypanosoma gambiensi infections

Only female mosquitoes are infected with Plasmodium, since only they feed on the blood of vertebrate hosts.In case of Trypanosoma gambiensi, infection through bite of tse tse flies.

12)The malaria parasite life cycle has 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.

Diagram given below clearly describes life cycle

Life cycle includes the following steps

1. Malaria infection begins when an infected female Anopheles mosquito bites a person, injecting Plasmodium parasites, in the form of sporozoites, into the bloodstream.
   
2. The sporozoites pass quickly into the human liver.
   
3. The sporozoites multiply asexually in the liver cells over the next 7 to 10 days, causing no symptoms.
   
4. In an animal model, the parasites, in the form of merozoites, are released from the liver cells in vesicles, journey through the heart, and arrive in the lungs, where they settle within lung capillaries. The vesicles eventually disintegrate, freeing the merozoites to enter the blood phase of their development.*
   
5. In the bloodstream, the merozoites invade red blood cells (erythrocytes) and multiply again until the cells burst. Then they invade more erythrocytes. This cycle is repeated, causing fever each time parasites break free and invade blood cells.
   
6. Some of the infected blood cells leave the cycle of asexual multiplication. Instead of replicating, the merozoites in these cells develop into sexual forms of the parasite, called gametocytes, that circulate in the blood stream.
   
7. When a mosquito bites an infected human, it ingests the gametocytes, which develop further into mature sex cells called gametes.
   
8. The fertilized female gametes develop into actively moving ookinetes that burrow through the mosquito's midgut wall and form oocysts on the exterior surface.
   
9. Inside the oocyst, thousands of active sporozoites develop. The oocyst eventually bursts, releasing sporozoites into the body cavity that travel to the mosquito's salivary glands.
   
10. The cycle of human infection begins again when the mosquito bites another person