Free Lamarckism MCQs with Answers

1. The central idea of Lamarck's theory of evolution is that

• A. variations arise at random and are then selected
• B. characteristics acquired during an individual's lifetime are passed on to its offspring
• C. species are fixed and do not change
• D. populations evolve by chance changes in allele frequency

Explanation: Lamarck proposed that an organism changes during its own life in response to need and environment, and that these changes are transmitted to the next generation, so evolution is directed by use rather than by selection. Random variation followed by selection is Darwin's very different mechanism. Lamarck did accept that species change, so fixity of species is the view he was arguing against.

2. Lamarck explained the long neck of the giraffe by suggesting that

• A. giraffes with longer necks survived and left more offspring
• B. a mutation in a growth gene lengthened the neck
• C. chance alone lengthened necks in a small isolated population
• D. each generation stretched its neck to reach higher leaves and the gain was inherited

Explanation: In Lamarck's account the effort of stretching lengthens the neck within the animal's own lifetime and the longer neck is then handed to the offspring, so the trait grows a little in every generation. Darwin's explanation, offered in the first option, starts from neck length varying at birth and lets the environment select among those variations. The two theories are distinguished by this exact contrast in almost every exam.

3. Lamarckism was finally rejected mainly because

• A. changes in body cells do not alter the genes carried in the germ cells
• B. organisms were found not to vary at all
• C. the fossil record showed no change over time
• D. no organ was ever found to degenerate through disuse

Explanation: Weismann's germ plasm idea, supported by his experiment of cutting off the tails of mice for many generations without shortening the tails of their offspring, showed that somatic changes leave the gametes untouched. Since only the gametes carry information to the next generation, an acquired character cannot be inherited. Variation and fossil change are both real and are the very evidence evolution rests on.

4. Lamarck's law of use and disuse states that

• A. an organ that is constantly used becomes better developed while a disused organ degenerates
• B. all organs of the body remain unchanged throughout life
• C. organs change only when their genes mutate
• D. an organ once lost can never reappear in any descendant

Explanation: This is the first of Lamarck's two laws, and he used it to explain the strong limbs of a blacksmith, the webbed feet of water birds and the loss of eyes in cave dwellers. His second law, the inheritance of acquired characters, is what turns these lifetime changes into evolution. Modern biology accepts that use develops an organ but denies that the development reaches the offspring.

5. Natural selection was proposed by

• A. Lamarck
• B. Darwin
• C. Mendel
• D. Wallace

Explanation: Charles Darwin proposed the theory of natural selection in 'On the Origin of Species' (1859).

6. The modern synthesis combines

• A. Darwin and Mendel
• B. Lamarck and Darwin
• C. Mendel and Morgan
• D. Watson and Crick

Explanation: The modern evolutionary synthesis combines Darwin's natural selection with Mendelian genetics and population genetics.

7. Which of the following best describes "acquired characteristics" according to Lamarckism?

• A. Traits caused by mutation
• B. Traits inherited from parents
• C. Traits developed by use or disuse
• D. Traits selected by nature

Explanation: Lamarck held that an organ strengthens with use and withers with disuse during an individual's own lifetime, and that this change is then passed on. Weismann's germ plasm work disproved the inheritance step, since changes to body cells never reach the gametes. Mutation and natural selection belong to the modern account that replaced it.

8. According to Lamarck, the evolution of long necks in giraffes is explained by:

• A. Natural selection
• B. Genetic mutation
• C. Survival of the fittest
• D. Stretching of necks over generations

Explanation: In Lamarck's account each giraffe stretched to reach higher leaves, its neck lengthened a little during its own life, and that gain was passed to its offspring. Darwin's explanation instead starts from neck length varying at birth and lets the environment select among those variations, which is what the first and third options describe. This single example is the standard way of contrasting the two theories.