Use the following choices to answer questions 2 and 3:
1. metacercaria
2. redia
3. adult
4. miracidium
5. cercaria


Put the preceding stages in order of development, beginning with the egg.
a. 5, 4, 1, 2, 3
b. 4, 2, 5, 1, 3
c. 2, 5, 4, 3, 1
d. 3, 4, 5, 1, 2
e. 2, 4, 5, 1, 3

Verified step by step guidance

1. Identify the life cycle stages of a typical trematode (fluke) starting from the egg.
2. Understand that the life cycle stages include: miracidium, redia, cercaria, metacercaria, and adult.
3. Recognize that the typical order of development from the egg is: miracidium, redia, cercaria, metacercaria, and adult.
4. Match the stages to the corresponding numbers given in the problem: miracidium (4), redia (2), cercaria (5), metacercaria (1), adult (3).
5. Select the option that matches the order: 4, 2, 5, 1, 3, which corresponds to option b.

Key Concepts

Life Cycle of Trematodes

Trematodes, or flukes, have complex life cycles that typically involve multiple stages and hosts. The life cycle begins with eggs, which hatch into larvae, and progress through various forms such as miracidium, sporocyst, redia, cercaria, and finally, the adult stage. Understanding this cycle is crucial for answering questions about the developmental order of these stages.

Miracidium

The miracidium is the first larval stage of trematodes, emerging from the egg in water. It is a free-swimming, ciliated larva that seeks out a suitable intermediate host, usually a snail, where it will develop further. Recognizing the role of the miracidium is essential for understanding the initial phase of the trematode life cycle.

Cercaria

Cercaria is a later larval stage of trematodes that emerges from the intermediate host, typically after developing from the redia stage. This motile larva is capable of swimming and can infect a definitive host or encyst to become metacercaria. Identifying the cercaria stage is important for determining the sequence of development in the life cycle.