Earth's service would be bare. There would no longer be life and all water ways would become dried up due to the intense ultra-violent rays of the sun.
Answer:
a. Ligase
b. Ligase (
it's repeated)
Explanation:
DNA synthesis begins, therefore, by synthesizing a short segment of RNA called a primer, which primer is synthesized by an enzyme called Primasa. Primasa is an RNA polymerase that uses DNA as a template. All fragments of Okazaki begin with a Primer. Subsequently, the DNA polymerase III Holoenzyme performs the synthesis of the corresponding DNA fragment until it reaches the next primer. At that time, DNA polymerase Ia replaces the DNA polymerase Holoenzyme III. The DNA polymerase I is responsible for removing the RNA primer through its 5'P-3'OH exonueotic activity and at the same time fills the hole by synthesizing DNA.
Finally, the two Okazaki fragments have to be joined, it is necessary to link the 3'OH end of a fragment with the 5'P of the next fragment. This work of sealing and joining the successive fragments is done by Ligase.
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.
Because our bodies work to fight off unknown substances like bacteria
