Answer:
The correct answer is: d. REs activity is best preserved by freezing the RE and thawing it out for brief periods of time as needed.
Explanation:
- Restriction enzymes can be defined as endonucleases that can recognize specific nucleotide sequence in a DNA (Deoxyribonucleic acid) sequence and cause breakage of phosphodiester bond in the DNA at the target site. Hence, it has the capacity of cleaving a DNA sequence.
- These are made up of proteins which are required to be present in the accurately folded conformation in order to function.
- Any form of alteration in the three-dimensional structure of the protein induced due to physical, chemical, mechanical or physiological factors can cause denaturation of the protein which in turn can render the protein non-functional.
- Freezing of restriction enzymes (REs) directly without the use of glycerol will cause the movement of water molecules within the proteins as well layering of water molecules on the protein surface.
- At low temperature these water molecules change to ice crystals which can alter the conformation of the protein or can cause breakage of peptide bonds in the proteins by physical force.
- This can cause the protein to get denatured and hence non-functional.
- Hence, it is never advisable to preserve REs by freezing directly without glycerol.
- Glycerol forms a layer around the protein molecules and prevents the protein molecules from coming into direct contact with the water molecules and hence prevents protein denaturation.
Answer:
The answer is A. Human activities have a greater impact on terrestrial and freshwater ecosystems.
Explanation:
creation of new organisms
reproduction of new cells
When cells are damaged, they usually die. Also, they don't grow, instead, they multiply to form new tissue. Therefore, answers (1) and (3) are not correct.
The answer is the first one
Oil spill or a discharge from pipe from a factory or sewage system. Since this is a single point of origin water pollution, this type of water pollution furnish itself to relatively easy remediation.
What is point source water pollution?
Point-source water pollution is the one type of water pollution which is easy to recognize because it generates from a single source or event and affects a specific area.
The negative effects of single point origin is deteriorating water quality which damage the environment, health conditions.
Destruction of biodiversity is another negative effect of water pollution depletes aquatic ecosystems and prompt unbridled proliferation of phytoplankton in lakes called as eutrophication.
The solution to reduce water pollution is reduce carbon dioxide emissions to prevent global warming and acidification of the oceans. Another is to reduce the use of chemical pesticides and nutrients on crops.
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