Gregor Mendel, an early pioneer in the field of genetics, helped shed light on how traits pass from one generation to the next. Mendel crossbred different strains of pea plants and meticulously tracked the results. He observed that certain characteristics of the plants, such as flower color, were present in new generations in predictable ways. His carefully kept notes showed that when a purebred white-flowered plant was crossed with a purebred pink-flowered plant, the resulting offspring always had pink flowers. However, the white-flower trait would consistently reappear in later generations. Mendel concluded that the pink trait was dominant while the white trait was recessive—masked by the dominant pink trait but still lurking somewhere in the plant.
Subsequent experiments would demonstrate the veracity of Mendel's findings by replicating his studies and confirming his results. However, it would be nearly a hundred years before the mechanism of this inheritance was discovered. We now know that genes are responsible for the pattern that Mendel observed in his pea plants. Plants and animals usually have two copies of the same gene, one from each parent. It's only when both copies are recessive that the recessive trait—in Mendel's experiments, the trait for white flowers—is expressed, or made visible.
What is the meaning of meticulously as used in the passage?