Question

How can we keep a tadpole of frog unchanged, in the same stage for a pretty long time?
A. Maintain them on very little food.
B. Provide them with a diet rich in proteins.
C. Add a lot of thyroxine to the aqueous medium in which they are kept.
D. Provide them an antithyroid substance like thiourea.

Answer 1

Hint: The process of Tadpoles changing into frogs is known as metamorphosis. Metamorphic failure can result from the lack of thyroid-stimulating hormone. This hormone is used to induce the thyroid to generate thyroxine in transforming the tadpoles. When tadpoles are given an antithyroid substance (like thiourea), they stop metamorphosis and cannot be transformed into bigger adults (frogs).

Complete answer:
Option A- Maintain them on very little food.
The tadpoles need to be fed regularly as they're growing and are always searching for food. One feed session every day keeps them healthy. It is also suggested that you should feed them every other day but in larger amounts.
Option B- Provide them with a diet rich in proteins.
Tiny tadpoles require meals that are rich in protein and calcium, including boiled greens, egg yolks, and store-bought tadpole food. They need this to grow into
Tadpoles need their protein from sources other than meat, especially when they reach the stage where their back legs are beginning to form.
Option C- Add a lot of thyroxine to the aqueous medium in which they are kept.
Thyroid hormone (TH) is the most crucial hormone in frog metamorphosis which is a developmental process. It will not occur in the absence of TH whereas it can be induced precociously by exogenous TH.
Option D- Provide them an antithyroid substance like thiourea.
The presence of an antithyroid substance inhibits the synthesis of thyroid hormone. e.g., thiourea. Therefore, tadpoles remain in the larval stage indefinitely. Thiourea is an organic compound of carbon, nitrogen, sulfur, and hydrogen, which is similar to urea, except that the oxygen atom is replaced by a sulfur atom

Thus, the correct answer is an option (D), 'Provide them an antithyroid substance like thiourea'.

Note: Tadpoles possess gills to help them breathe under the water and have tails and fins to help them swim. Whereas Frogs possess arms and legs that help them swim underwater. After hatching tadpoles take about 14 weeks to transform into tiny frogs.