DDT stands for dichloro-diphenyl-trichloroethane. The first kind of synthetic/artificial insecticides came into use in the 1940s. The earlier usage of DDT include: a) Killing of malarial vectors, b) Combatting Typhus and other insect borne human diseases, c) As a pest control in crops d) as a pest control in garden, live stock production and even at homes.
The negative impact of DDT could be felt for the first time when the pests that were earlier killed by use of DDT have now become pesticides resistant. In the 1950s in USA, the regulatory measures were adopted to reduce the usage of DDTs as its effects as a pesticides were no more long significant and also it was creating detrimental physical and psychological impacts on the human and environment.
It was in 1972 that the U.S. Environmental Protection Agency cancelled the order for banning the usage of DDT based on the adverse impact it produced on the environment, human and other life forms. Since then continuous studies are being conducted to analyse the impact of DDTs. In some later years it was established that DDT is the cause of producing tumors in liver.
Some of the common negative impacts produced by DDT as per the U.S. Department of Agriculture :
a) The non destructive nature – DDT can not be destroyed and thus it remains persistent in the atmosphere
b) It attacks the tissues of living organisms especially the animals and humans ( fatty tissue)
c) It can penetrate the atmosphere to deeper extent.
Now as per the current stuation, The use of DDT is controlled and other alternatives of pest control organisms is being deduced. As per the treaty of Stockholm Convention on POPs (Persistent organic pollutants) , usage of DDT for malarial control is justified but it puts a restrictive use of DDT as pesticides in other areas.
Answer:
Sodium chloride removes proteins from DNA and helps in DNA precipitation.
Explanation:
The Deoxyribonucleic acid (DNA) is negatively charged due to the highly polar phosphate groups that make up the phosphate backbone. The molecules of water are also highly polar and they have positive charge, thereby water molecules interact with the negative charges of the DNA. The sodium chloride generates temporary attraction forces between sodium (positive) ions and the DNA backbone (negative), thereby DNA can be disassociated from the aqueous layer. Moreover, sodium chloride helps to remove proteins (histones) that bound to DNA and also helps to maintain proteins in the aqueous layer.
Answer:
Bioluminescence is the phenomenon which is seen in the dinoflagellates which is very common. It is caused due to chemical reactions that takes place inside the organism.
There is an influx of protons in the cell which drops the pH of the cell. It is the oxidation of luciferin which produces the glow.
This phenomenon acts as a shock for the predator because it is in the form of flash for less than 20 microseconds.This flash reduces the number of dinoflagellates which is being eaten by the predator.
The best answer would be B.
high sodium foods definitely cause edema. But alcohol also has a relationship with edema. Still best answer is b.
Answer:
the answer to this question is the light colour
