Answer:
I would expect that the sample has only 50% of the original 235 U.
Explanation:
That is because 235 U has a half-life of 700 million years and I expect that my sample be 350 million years old. 350 is half of 700.
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:constriction of pupil
Explanation:the circularly arranged smooth muscle fibers in the highlighted structure ie the iris causes constriction of the pupil.
The iris basically has ciliary muscles that control Lens shape ,this happens when the ciliary muscles under the signal of the parasympathetic nervous system contract leading to the constriction of the pupil and when these muscles relax then dilation of the pupil will occur
Answer:
<h2>A</h2>
Explanation:
Pepsinogen is an inactive enzyme which is activated into active digestive enzyme known as pepsin. It is a digestive enzyme which causes breakdown of proteins. Active pepsin causes cleavage of more pepsinogen molecule by a positive feedback loop and leads to increase in the concentration of active pepsin molecule.
Its concentration increases according the requirement in the body which is controlled by feedback system.
The answer is R. The structure of singulair (montelukast), a medication used to manage asthma, the absolute absolute configuration of the chirality center is r and not s. Montelukast is aeukotriene receptor antagonist used to relieve symptoms of seasonal allergies.and used <span>for the maintenance treatment of asthma.</span>
