Practice Questions

Lamarckism is rejected because somatic changes (acquired characters) cannot alter germ-line DNA, meaning they cannot be inherited under modern genetic principles.

Lamarck proposed that the giraffe's ancestors had short necks but stretched them to reach leaves on high branches, leading to a longer neck through "use" which was then inherited.

Both Darwin and Lamarck recognized that organisms adapt to their environments over time, though they proposed different mechanisms for how these adaptations occur.

Under the use and disuse principle, frequent running strengthens and elongates the limbs, and under the inheritance of acquired characters, this trait is passed down.

Lamarck's first postulate suggested that living organisms possess an inherent internal vital force that drives them toward greater organizational complexity.

Lamarck believed in "phyletic transformation" rather than absolute extinction; he argued that species do not die out but continuously evolve into newer, more complex forms.

While Lamarck recognized adaptation to the environment, he did not propose natural selection (survival of the fittest based on pre-existing genetic variations) as the mechanism.

Lamarck explained webbed feet as an acquired physical modification resulting from the continuous effort of spreading the toes to push water while swimming.

Modern genetics shows that phenotype changes in somatic tissues (like muscle hypertrophy from working out) do not alter the DNA sequences of germ cells, making inheritance impossible.

The colorful plumage of male peacocks is a product of sexual selection (Darwinian concept). Lamarck focused on physical adaptations gained through use (webbed feet, long wading legs) or disuse (limbless snakes).