Question

In the development history of the mammalian heart, it is observed that it passes through two fish-like hearts, three chambered frogs like hearts and finally four chambered stages. To which hypothesis can this above cited statement be approximated?
A. Biogenetic law
B. Hardy Weinberg law
C. Lamarck's principle
D. Mendelian principle

Answer 1

Hint:- Mammals belong to kingdom vertebrata. Evolution is defined as gradual and slow changes in the living forms. Time to time the need was felt to develop an advanced heart so that mixing of oxygenated and deoxygenated blood does not occur . So mammals developed four chambered hearts.

Complete answer: The hearts in various vertebrates ( fishes , amphibians , reptiles ,birds and mammals) show similarity is a basic plan but they have varied degrees of specialization according to habitat in which they live , energy requirement and scale of evolution.
This occurs to ensure double circulation that mammals developed four chambered hearts.
Now let us match this with given options:-
A) Biogenetic law :- This law was proposed by Ernst Haeckel . He told that ontogeny recapitulates phylogeny. Ontogeny is defined as the life history of an organism and phylogeny is defined as an evolutionary relationship. So organisms develop better and better structures to adapt themselves.
Hardy Weinberg law :- This principle states that a population is said to be in genetic equilibrium if it is not undergoing any kind of evolutionary change. Genetic equilibrium means that the frequency of occurrence of alleles of a gene is supposed to remain fixed and even remain the same through generations.
Lamarck's principle :- According to this theory the organisms undergo changes to adapt themselves to the environment. The changes acquired by the organisms during their lifetime are passed onto the next generation.
Mendelian principle :- this principle states that characters are passed from parents to offspring . It gave the principle of genetics . It shows that genes or factors are heritable in nature which pass successfully from one generation to another.

Our required option is biogenetic law.

Note:- Darwin said that evolution is a slow and gradual process which takes a lot of time to proceed but de Vries believed that evolution occurs suddenly. The single step large mutation which can cause speciation was
named saltation by de Vries. thereby evolution and mutation causes change in chambers of heart