Practice Questions

"Besoin" refers to the inner need or urge felt by an organism when faced with environmental change, prompting it to alter its behavior and use certain organs more than others.

Lamarck's "Philosophie Zoologique" was published in 1809, which coincidentally was the year Charles Darwin was born.

Epigenetics involves study of heritable changes in gene function (like DNA methylation or histone modification) caused by environmental factors without altering the underlying DNA sequence, conceptually echoing Lamarck's environmental influence.

Under Lamarckism, the continuous disuse of eyes in a dark cave environment leads to developmental decay, which is then inherited by subsequent generations.

Lamarck postulated that the continuous disuse of an organ leads to its gradual degeneration, reduction in size, and ultimate disappearance (vestigialization), as seen in the limbs of snakes.

Weismann's Germplasm Theory states that only changes in the germ cells (germplasm) are transmitted to offspring, while somatic cells (somatoplasm) do not pass genetic info to the next generation.

August Weismann cut off the tails of mice for 22 consecutive generations. The offspring of the 23rd generation still developed normal tails, proving that somatic modifications (mutilations/acquired traits) are not inherited.

The elongation of the giraffe's neck via stretching (use of organ) and subsequent inheritance of this stretched neck is the classic textbook example of Lamarckism (Inheritance of Acquired Characters).

Lamarck's fourth postulate states that somatic modifications acquired during an organism's lifetime due to use/disuse are directly transmitted to the next generation.

Lamarck's theory posits that environmental changes create new needs ("besoin") in an organism, which drives changes in habits, leading to the use or disuse of specific organs.