Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. they identify the gene responsible for toxin production. the dominant allele (t) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. heterozygotes produce an intermediate amount of toxin. the genotypes of all individuals in the population are determined (see chart) and used to determine the actual allele frequencies in the population.

Small milkweed toxin production is the result of incomplete dominance.

There two types of alleles:

T = Dominant allele.

t = Recessive allele.

And these two alleles will produce three types of genotypes:

Dominant homozygous= TT = The production of high amount of toxin.

Recessive homozygous = tt =The production of no toxin.

Dominant heterozygous = Tt = The production of intermediate amount of toxin.

Incomplete dominance is a genetic phenomenon in which dominant allele is not fully expressed in form of heterozygous genotype.

The dominant allele expression depends upon the frequency of allele in genotype.

stridor can't collapse a lung.

from almost the creation of the first true maps of the earth, people started seeing how continents would be able to fit together.   in particular, people noticed that south america fits almost exactly into africa.

you should be aware that while world maps were around early in the 1600’s and better defined by the end of the 1700’s, those maps were not ‘public’ but were treated as state secrets.   and so it was not till much later that the broader ‘science’ community had access to good quality and accurate world maps.

get the whole story here…

it is now known that most of the major continental masses can be fit together in a jigsaw process.   in fact we now know that the continents were indeed once all joined together as one land mass – the supercontinent of pangaea.

if you look at most world maps you will ponder how this is evidence, as the continents really don’t appear to ‘fit’ together very well.   what you need to understand is that the vast majority of maps are drawn using a map projection that has the north and south poles (which are points) are a line the width of the map at the top and bottom.   this means that the map distorts the true shape of the earth’s land and oceans as you love closer to the poles.     some other map projections distort less, but have the map shape looking like segments of an orange.   see here for a range of map projections.   check out the way greenland changes size in each!

what is more remarkable, is the next piece of evidence when added to the shape of continents.

location of mountains and fossils

what is remarkable, when you reassemble all the continents together, the ancient mountain ranges (many now eroded to their cores) and the location of rock types and fossils all match up.