Question

A proglottid of Taenia is called gravid only if it has -
(a) Both male and female reproductive organs are well developed.
(b) Only female organs that are well developed.
(c) A well-developed uterus filled with eggs.
(d) Becomes dead.

Answer 1

Hint: Taenia is the scientific genus of the tapeworm. It is an organism responsible for diseases in humans that passes from infected food. Their body has a ribbon-like morphology composed of segments known as proglottids. The gravid proglottid is necessary for reproduction which is a segment required for the storage of eggs.

Complete answer:
- Taenia, the genus of tapeworms have a ribbon-shaped body that is composed of segments known as proglottids.
- Each proglottid is classified as immature, mature, or gravid. The gravid proglottid is the oldest proglottid, located at the posterior end of the strobila, a polyp formed in transverse fission. This segment has no reproductive organs and only has a uterus filled with eggs.
- Hence, the proglottid of the tapeworm is called gravid only if it is a uterus storing eggs.
- Tapeworms are also known as cestodes. They are well-known for causing the diseases taeniasis and cysticercosis in humans that are forms of helminthiasis.
- The branched uterine structure in the gravid proglottids is helpful in distinguishing species of tapeworms.
- Tapeworms are hermaphrodites, they have both male and female reproductive organs.
- Taenia infections are diagnosed by finding gravid segments of adult tapeworms in stool specimens; the eggs of these species are indistinguishable.

So, the correct answer is ‘ a well-developed uterus filled with eggs.’

Note:
- Tapeworms are parasites that affect humans, domestic animals, and other animals humans use for food, such as fish.
- These worms do not possess a circulatory system. Additionally, they do not have a mouth or a digestive tract.