Question

Miracidium gives rise to
A. Sporocyst after entering snail
B. Sporocyst in contact with aquatic vegetation
C. Redia after entering snail
D. Redia in contact with aquatic vegetation

Answer 1

Fasciola hepatica is commonly called liver fluke. It is a parasite which completes its life cycle in two hosts. The hosts are sheep and freshwater snail. Miracidium is the larval stage of the liver fluke.

Complete answer:
The life cycle of Fasciola hepatica is completed within two hosts. The primary host is the sheep and snail is the secondary host. The parasite whose life cycle requires two hosts to complete is called a digenetic parasite.
When the sheep eats the plant with the metacercaria stage of the parasite, it goes into the digestive system of the sheep. The cyst wall is digested in the intestine and the parasite reaches the liver through the intestine wall. In the liver, it takes six weeks to become an adult. The liver fluke undergoes copulation in the bile duct of sheep. After copulation and fertilization occurs. The fertilized egg is surrounded by yolk cells and is developed into shelled egg. The shelled egg migrates to the intestine through bile duct. The eggs come out of the sheep through its faecal matter. These eggs undergo early development under favourable environmental conditions. At suitable temperature and favourable conditions, the egg gives rise to Miracidium larva. The miracidium larva swims in the water.
While swimming, the miracidium larva comes in contact with the snail; it penetrates into the soft body of the snail. In the body of snails miracidium develops into sporocyst stage.

Therefore, option A. Sporocyst after entering the snail.

Note: Fasciola is a digenetic parasite. It is included in the phylum Platyhelminthes. The primary host is sheep in which flukes develop. Eggs come out with sheep faeces. After several weeks the eggs hatch into larva, the miracidium. Miracidium then infects a snail and under optimal conditions, miracidium develops into sporocyst.