**Comprehensive Biology Practice Exam: Exploring Core Concepts and Applications**

Natural selection is a fundamental mechanism of evolution proposed by Charles Darwin. It is based on the concept that individuals with favorable traits for their environment are more likely to survive, reproduce, and pass on those traits to their offspring. Over time, this process results in the adaptation of species to their environment. The process of natural selection involves several steps: Variation: Within a population, there is genetic variation due to mutations, genetic recombination, and sexual reproduction. Individuals have slightly different traits. Selection Pressure: Environmental factors, such as predation, competition for resources, or changes in climate, create selective pressures that favor certain traits over others. Individuals with advantageous traits are more likely to survive and reproduce. Differential Reproduction: Individuals with advantageous traits have a higher chance of surviving and reproducing, passing on their beneficial traits to their offspring. This leads to an increase in the frequency of those traits within the population over generations. Accumulation of Traits: Over many generations, the frequency of favorable traits increases, while less advantageous traits decrease. This process results in the adaptation of the population to its environment. Speciation: If populations become isolated or experience different selection pressures, they may accumulate different traits, leading to the formation of new species over long periods of time. Natural selection drives the gradual change of species over time, leading to the development of complex adaptations that enhance an organism's fitness in its specific environment. It is the cornerstone of Darwin's theory of evolution and has been supported by numerous observations and experiments in the fields of genetics, paleontology, and ecology.