Answer:
b. A second marker in the knock-out cassette, that if inserted into the genome results in cell death when plated on selective media.
Explanation:
General recombination, also known as homologous recombination, refers to the naturally occurring process of exchange of genetic material between pairs of homologous DNA sequences. This process (homologous recombination) can be exploited by genetic engineering to insert DNA segments of interest at target genes. Moreover, a cassette is a mobile DNA segment containing almost a gene and a recombination site, which is integrated into the <em>locus</em>/<em>loci</em> of interest by homologous recombination. A cassette may contain a DNA segment called 'negative marker' which prevents growth under particular conditions, while a positive marker permits growth under certain conditions. In consequence, a second marker consisting of a drug cassette may be used as a negative marker in order to evidence its insertion by inducing cell death when they are plated in selective conditions.
Pp is the genotype because you know purple must have a gene of purple, which it says is dominant. If the white is recessive, the purple with dominate the white.
With the overuse of chemical fertilizers, many lawns now have it to where decomposers can't live. This interferes most directly with the lawn ecosystem to recycle important nutrients. The correct answer is choice number 2.
