DNA supercoiling means under or over winding of the DNA strand and basically is to become more condensed and more organized. Supercoiling is very important as it compacts the genetic code and as if that was not enough supercoiling also regulates and oversees the access the the genetic code.
<h3><u>Answer;</u></h3>
A. Gas exchanges takes place by diffusion.
B. It is an open system.
<h3><u>Explanation</u>;</h3>
- Most molluscs and arthropods have an open type of circulatory system.
- Open circulatory systems pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells.
- Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.
The best and most correct answer among the choices provided by your question is the fourth choice or letter D. Reptiles are the most critically endangered animal group. Their population is threatened due to illegal activities done by man like poaching.
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Natural selection is the process in which the more favorable traits due to mutation that are in a select few in a population produce more offspring then others. An example of this is bacteria resistant to antibiotics due to the faster reproduction of the resistant bacteria over the non resistant ones
