The answer is concrete laundry trays.
This is because as concrete trays ages with timeit becomes coarse and rugged due to water, soap and detergents. Their smoothness gradually fades with time, thus this makes it not as good regarding to health wise standards of living.
Cross contamination means the transfer of pathogens from surface to another
Answer:
The F1 progeny is completely heterozygous for the <em>loci</em> of interest since they were obtained by mating between two pure-breeding plant lines. In the next generation, the backcross progeny will have homo-zygous individuals and therefore they will be more variable, resulting from meiosis in F1 hybrids
Explanation:
An F1 resulting from the cross between two pure-breeding plant lines will produce all hybrid individuals, all of them genetically (and phenotypically) identical. Meiosis in F1 hybrids is well known to produce homo-zygous genotypes and thus increases genetic diversity in progeny. For instance, for a single <em>locus</em>, the expected ratio of genotypes obtained from crossing two heterozygous parents is 1:2:1, i.e., one homo-zigous dominant individual, two heterozygous individuals (genetically identical to the parents) and one homo-zygous recessive individual; while the expected phenotypic ratio is 3:1 (i.e., 3 dominant expressing: 1 recessive expressing).
