Lamarcks theory of inheritance of acquired characters was later challenged and disproved by experiments carried out by which scientist?

Introduction / Context:
Jean Baptiste Lamarck proposed an early theory of evolution that suggested organisms could pass on traits acquired during their lifetime to their offspring. This idea is known as the inheritance of acquired characters. Later scientists tested this theory experimentally and found evidence against it. Exam questions often ask which scientist most famously challenged Lamarcks theory through experiments.

Given Data / Assumptions:

• The theory in question is Lamarcks inheritance of acquired characters.
• The options list August Weismann, Hugo de Vries, Herbert Spencer, and Carl Linnaeus.
• We assume general knowledge of the contributions of these scientists.
• The question asks who challenged Lamarcks idea experimentally.

Concept / Approach:
August Weismann, a German biologist, proposed the germ plasm theory and separated the concept of germ cells (reproductive cells) from somatic cells (body cells). He argued that only changes in germ cells could be inherited and that changes in body cells acquired during life would not affect offspring. Weismann famously cut off the tails of mice for many generations and observed that their offspring still had normal tails, providing experimental evidence against the inheritance of acquired characters. This work directly challenged Lamarcks theory.

Step-by-Step Solution:
Step 1: Identify Lamarck as the scientist who proposed that acquired traits, such as a giraffes stretched neck, could be passed to offspring. Step 2: Recall that August Weismann introduced the germ plasm theory, which states that hereditary information is carried only in germ cells, not in somatic cells. Step 3: Weismann carried out experiments on mice by cutting off their tails repeatedly for many generations. Step 4: He observed that the offspring continued to be born with normal tails, showing that the acquired absence of a tail in parents was not inherited. Step 5: This experimental evidence contradicted Lamarcks idea that acquired characters could be passed on, so August Weismann is the correct answer.

Verification / Alternative check:
Evolutionary biology texts usually summarise Lamarcks theory and then explain how it was replaced by Darwinian natural selection and later findings in genetics. In that historical narrative, August Weismann is highlighted for his experiments on mice tails and his concept of germ plasm. Hugo de Vries is mentioned for mutation theory, Herbert Spencer for applying evolutionary concepts to sociology, and Carl Linnaeus for developing the binomial classification system. Only Weismann is described as directly challenging the inheritance of acquired characters through experiments.

Why Other Options Are Wrong:
Hugo de Vries developed the mutation theory of evolution and worked on evening primrose plants, but his work did not primarily focus on disproving Lamarcks mechanism. Herbert Spencer coined phrases like survival of the fittest and applied evolutionary ideas to society, but he did not conduct the germ plasm experiments that refuted Lamarckian inheritance. Carl Linnaeus created the modern system of naming and classifying organisms but lived before Lamarck and therefore did not challenge his theory.

Common Pitfalls:
Some students may confuse the names of evolutionary thinkers and choose Hugo de Vries because his name appears frequently in discussions of evolution. Others might pick Linnaeus simply because he is a famous biologist. To avoid confusion, associate each scientist with a key idea: Lamarck with inheritance of acquired characters, Weismann with germ plasm and tail cutting experiments, Darwin with natural selection, de Vries with mutation theory, and Linnaeus with classification. This mapping will help you quickly identify August Weismann as the one who challenged Lamarcks theory.

Final Answer:
The correct choice is August Weismann, whose germ plasm theory and experiments on mice tails provided strong evidence against Lamarcks inheritance of acquired characters.