MCQs

"Soft inheritance" refers to the inheritance of acquired characters, where the genetic material is not fixed but can be modified directly by environmental influences during an organism's life.

Darwin proposed Pangenesis to explain how physical modifications in body parts might be communicated to reproductive cells, aligning closely with Lamarckian inheritance.

Lamarckism posits that the plant responds to the environmental dry stress by adapting its physiology (succulence) to meet its new need, then transmitting this acquired trait.

Orthogenesis (straight-line evolution) is conceptually linked to Lamarck's internal vital force, suggesting organisms have an innate drive to evolve in a specific, progressive direction.

Mutilating the tail alters somatic tissue (somatoplasm) but leaves the germplasm (reproductive cells) untouched, demonstrating that somatic changes are not inherited.

This is Lamarck's second postulate (environmental changes produce new needs, which lead to the development of new organs through effort or behavior).

Lamarckism explains vestigial organs (like the human appendix, coccyx, or wisdom teeth) as structures that lost their function and gradually degenerated due to continuous disuse over generations.

Under Lamarckism, the mental training/acquired skill of navigating the maze would be passed to the offspring, making subsequent generations progressively better at it without training.

Lamarck argued that variations are purposefully acquired during life in response to environment, whereas Darwin proposed that variations exist naturally in a population before natural selection acts.

Under Lamarckism, the disuse of wings because of terrestrial lifestyle and abundant ground-level resources led to the degeneration of wings over generations.

Genetic engineering alters the genome directly. Lamarckism refers to somatic phenotypic changes (like organ use/disuse) being converted into heritable genetic info, which does not happen here.

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.