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.
I think that it’s c but I could be wrong!
Answer:
To determine the flask on basis of the molarity or concentration of the solutions, an individual should design an experiment with the help of using water and dialysis tubes. Dialysis tubes up should be filled with pure water, then seal or closed them from both ends.
Measure the weight and note the mass of each tube, student should stick label the cups with the solutions. Weighing the solutions after leaving them for 8 to 10 hours. The tubes would lose weight as water leave the tube when placed in the solutions due to the principle of diffusion- movement.
Answer:
A snowshoe hare produces a white coat during the winter, allowing it to better hide from predators. As a result, it has thrived and over time a majority of snowshoe hares in the population also produce white coats in the winter. Which of the statements is/are true?
The white-coated hare has a competitive advantage in its environment.
The new population of hares resulted from natural selection.
Explanation:
The analogy shown above describes the law of natural selection which explains why the organism that fits into a new environment survives as a result of inheritance of a distinct trait that differentiate them from others. Also, the organism has greater advantage over the environment because it has device means of survival over time
