Explain how the inheritance patterns of many traits (such as petal color in snapdragons, or skin color in humans) cannot be accounted for by Mendelian genetics.

Petal color in snapdragon is an example of incomplete dominance and deviates from Mendel's law of dominance.

Skin color in humans exhibits a continuous variation and is regulated by more than one genetic loci.

Explanation:

Two alleles of a gene do not always exhibit the dominant-recessive inheritance as shown by Mendel. The alleles controlling the petal color in Snapdragon exhibit incomplete dominance since the allele "R" is not able to produce enough pigment in heterozygous condition to completely mask the effect of the recessive allele "r" Therefore, the heterozygous genotype "Rr" gives pink color to petals.

Mendel showed that each genetic trait is regulated by one gene and exhibit discontinuous variations. This is not followed by skin color in humans which is a polygenic trait with multiple genes regulating it. Here, a range of phenotype is present which is regulated by the sum total of the dominant alleles of all the genes involved controlling the melanin production.

it’s lava came from an explosive eruption

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!