Nursing Entrance Exam (NEX) Practice Exam

Charles Darwin's theory of evolution suggests that the variations between species arise primarily from what mechanism?

1. The use or disuse of body structures

2. Exposure to mutagenic agents

3. Natural selection

4. Acquired characteristics

The correct answer is: Natural selection

Charles Darwin's theory of evolution posits that the variations between species arise primarily through the mechanism of natural selection. Natural selection is the process by which organisms that are better adapted to their environment tend to survive and reproduce more than others. This leads to the gradual increase of advantageous traits within a population over generations, as these traits are passed on to offspring. Darwin proposed that individuals within a species exhibit variations, and those with traits that offer a survival advantage are more likely to survive and reproduce. Over time, this can lead to significant changes in species as advantageous traits accumulate. This concept is fundamental to the understanding of how species evolve and adapt to their environments based on the pressures they face, such as predation, climate, and food availability. The other options relate to different concepts of change but do not align with Darwin's primary mechanism of evolution. The use or disuse of body structures refers more to Lamarckian evolution, which suggests that organisms can acquire characteristics during their lifetime that they pass on to their offspring, and this does not align with modern genetic understanding. Exposure to mutagenic agents introduces changes in DNA, but these are not the primary force behind the gradual process of evolution as described by Darwin. Acquired characteristics suggest that physical changes