BIO NMDCAT

Under Darwinism, variation exists prior to environmental change. Penicillin acts as a selective agent, removing susceptible cells and allowing pre-existing resistant cells to populate.

The differing beak morphologies are adaptations developed over generations as ancestral finches colonized islands with distinct food resources (seeds, insects, nectar).

Natural selection can only change the genetic makeup of a population over generations if the phenotypic variations being selected have an underlying heritable genetic basis.

Natural selection is a non-random, directional process that adapts populations to their environments, whereas genetic drift is random and non-adaptive.

Stabilizing selection favors intermediate variants by acting against extreme phenotypes, reducing variation and maintaining the status quo of a phenotypic trait.

Since the offspring of the salt-stressed plant reverted to normal thin leaves when grown in normal soil, the acquired trait (thick leaves) was not inherited, refuting Lamarck's theory.

Lamarck was a pioneer who proposed the first fully formed, systematic theory of organic evolution, paving the way for evolutionary thought despite his proposed mechanisms being incorrect.

Weismann established that only the genetic material in germ cells (sperm and egg) is passed to offspring; changes in somatic cells (like muscle or nerve) die with the individual.

Hypertrophy from physical work is a somatic adaptation (phenotypic plasticity). It does not alter germ-line DNA, so the children must still build their own muscles through work.

"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.

Lamarck believed that all living organisms possess an innate, vital force that drives them to become more complex, organized, and structurally perfect over time.

Lamarckism relies on individual-level somatic adaptation during a single lifetime, whereas modern evolutionary biology relies on population-level changes in allele frequencies over generations.

Lamarck's theory is widely known as the "Theory of Inheritance of Acquired Characters" or simply "Lamarckism."

Regressive evolution (simplification) contradicts the idea of an unstoppable, innate "internal vital force" that always drives organisms toward greater complexity and perfection.

Lamarckism explains webbed digits as physical structures acquired through repeated stretching of the skin during swimming (use), which is then inherited.

Morgan's work proved that hereditary traits are carried on chromosomes inside the cell nucleus, which are not altered by the somatic activities or "urges" of the animal.

Strictly applied, Lamarck's inheritance of acquired characters suggests that any physical change, including a lost limb, would be passed down (though Lamarckians later tried to exclude random accidents).

In Lamarckism, the environment forces the organism to change its physiology/behavior. In Darwinism, the environment simply "selects" which pre-existing variations survive.

Lamarck's third postulate states that active use of an organ strengthens and enlarges it, while continuous disuse leads to its structural decay and eventual loss.