Question

Trophozoite of Entamoeba histolytica contains
A. Many pseudopodia and two contractile vacuoles.
B. One pseudopodium and two contractile vacuole.
C. Cell wall with fixed pseudopodia.
D. Single pseudopodium and no contractile vacuole.

Answer 1

Hint: Entamoeba histolytica is a protozoan parasite found in the large intestine (colon) of human. Amoebiasis/Amoebic dysentery is caused by the Entamoeba histolytica. This disease causes constipation, abdominal pain, cramps and stools with mucus and excess blood.

Complete answer:
Trophozoite of Entamoeba histolytica contains single pseudopodium and no contractile vacuole. Housefly serves as mechanical carriers and transmits the parasites from faeces of infected people to food. Food is contaminated by the housefly and intake of contaminated food and water are the main source of infection.
Trophozoite is the adult form of Entamoeba and it is monopodial. It has two forms magna or pathogenic form found in the mucosa and submucosa of intestine forming ulcers and minuta is the non-pathogenic form found in the lumen of the intestine. The body of trophozoites is covered by plasmalemma and cytoplasm is differentiated into endoplasm and ectoplasm. A single, large and broad pseudopodia formed from ectoplasm and endoplasm contains nucleus and food vacuoles. Entamoeba has no contractile vacuole. Trophozoite of Entamoeba histolytica reproduces by binary fission. Minuta of trophozoite forms encysts. A mature cyst is called quadrinucleate cyst and it has four nuclei and two chromatid bodies. Tetra nucleate cyst is the infective stage.

So the correct answer is option D.

Note: Glycogen is the reserve food material in the cyst of Entamoeba histolytica. The skin, mucous membranes, antimicrobial substances (tears and saliva) and phagocytic cells block the entry of pathogens into our body. These are known as innate defenses of our body.