Fifty years ago, bed bugs were nearly eliminated in the United States by using of pesticides like DDT. Today bed bugs are back i
n beds and theaters. DDT is no longer used due to environmental issues. Pyrethrums are currently the top choice for bed bug infestations. Pyrethrums are especially useful to us because they generally have a stronger effect on bugs than on humans and animals. Some bed bugs had mutations in their genetic code which allowed them to survive the chemical pesticide and they produced chemically resistant offspring. How can this be explained?
What happened in the case of bed bugs and pesticides is natural selection at play. According to the natural selection theory propounded by Darwin, the environment selects for genes that able to withstand changes and organisms with such genes are able to survive, mate and pass on the selected gene to their offspring. Organisms without the selected gene gradually fades off from the population since they are not able to withstand the changes to the environment. Hence, after some considerable time, the desirable trait becomes dominant in the population.
<em>When DDT was in use, it was effective against bed bugs mutation in the genome of a few of the bed bug population conferred resistance against DDT on them. The environment selects this resistance trait because it is desirable. The resistant strains therefore, survive, mate and pass the gene to their offspring. After a while, bed bugs without the DDT-resistant gene die off the population while those with the resistant gene take over.</em>
This might eventually happen to Pyrethrums too in the nearest future if natural selection law is to be considered.
Since a mutation cause them to build up a resistance two chemicals they are more likely to survive and reproduce. since most of the bed bugs that are not resistant will die off it is very likely that two chemically resistant bed bugs will mate and reproduce resulting in a almost a hundred percent chance that The Offspring will also be chemically resistant. or the bedbugs could go through a process of natural selective breeding where the parents that are chemically resistant purposely breed with other chemically resistant bed bugs knowing that their offspring would be more likely to survive based on past experience.
C3 photosynthesis produces a three-carbon compound via the Calvin cycle while C4 photosynthesis makes an intermediate four-carbon compound that splits into a three-carbon compound for the Calvin cycle. Plants that use CAM photosynthesis gather sunlight during the day and fix carbon dioxide molecules at night.
Answer is the first option Place a metal paper clip on a table and slowly bring each electromagnet closer to the paper clip to see which can attract the paper clip from a greater distance.
I don't know why but I find your questions a bit too easy..
