Question

The presence of gill slits, in the embryos of all vertebrates support the theory of?
A. Metamorphosis
B. Biogenesis
C. Organic evolution
D. Recapitulation

Answer 1

Hint: Gill slits are a series of linear openings present on the exterior side of pharynx of fishes and some amphibians, which are used for gas exchange.

Complete Answer:
Let’s analyse the options one by one for finding the correct answer,
- Option A: Metamorphosis is a biological process where observed a profound change in morphology of an organism from one life stage to next after hatching. The change from caterpillar to pupa and then to butterfly is an example of this. Therefore, this is an incorrect option.
- Option B: Biogenesis is referred to the formation of life from pre-existing life. Therefore, this is an incorrect option.
- Option C: Organic evolution is referred to a change between generations, within a lineage of population . It says an organism of a population differs genetically from its ancestor and descendants due to the responses to environmental changes. Darwin’s theory of evolution is an example of this. Therefore, this is an incorrect option.
- Option D: Recapitulation theory says that the embryo of an animal will go through stages resembling their ancestors. It is also known as embryological parallelism. Vertebrates like reptiles and mammals are evolved from fishes and amphibians over time. Therefore the presence of gill slits in vertebrate embryo stages can be explained by recapitulation. This is the correct option.

Hence, the correct answer is option D) Recapitulation.

Note: Ernst Haeckel proposed recapitulation theory. Example of recapitulation theory is tadpoles, which are frog larvae that have the tail and gills which imply they are developed from fishes.