Answer:
The answer is B. Some organic molecules, including amino acids, could have been produced from chemical reactions on early Earth.
Explanation:
Miller-Urey Experiment:
The Miller-Urey experiment was an attempt to explain the origin of life on Earth. Miller-Urey simulated the primordial soup i.e. the environment of primitive Earth to prove the spontaneous generation of organic molecules. The conditions they introduced included:
- A methane-ammonia-hydrogen and water mixture that exactly simulated the primordial soup.
- A spark of 70,000 volts that simulated lightening.
- A temperature of 800 degree Celsius.
Observations:
- After running for 18 days, the final solution was examined for presence of organic molecules.
- Miller-Urey observed that most of the methane and ammonia had been consumed and the mixture contained carbon monoxide and nitrogen.
- The solution further contained 25 amino acids (mainly, glycine, alanine and aspartic acid)
, several fatty acids
, hydroxy acids and amide products.
The experiment concluded that simple organic compounds such as amino acids could have been formed through spontaneous generation under the Earth's primitive environmental conditions.
This reduction in starch content occurred because starch was changed into simple sugars
<h3>Explanation:
</h3>
Starch is a polymeric carbohydrate consist of many glucose units linked by glycosidic bonds. The iodine test is used to test for the presence of starch. Starch will change color to an intense "blue-black" colour after the addition of aqueous solutions of the triiodide anion. To do it we can add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour The reaction between amylose that present in lesser amounts and iodine is said to account for the intense color change seen.
An iodine test of a tomato plant leaf revealed that starch was present at 5:00 p.m. on a sunny afternoon in July. When a similar leaf from the same tomato plant was tested with iodine at 6:00 am the next morning, the test indicates that less starch was present in this leaf than in the leaf tested the day before. This reduction in starch content occurred because starch was
- 1. changed directly into proteins
- 2. transported out of the leaves through the guard cells
- 3. transported downward toward the roots through tubes
- 4. changed into simple sugars
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This occurred because one phenotype was completely dominant over the other phenotype.
Hope this helped you.
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.
