Answer:
Hydrogen Bonds
Explanation:
In the polymerase chain reaction (PCR) the temperature rises to 90 ° C - 95 ° C, to break the hydrogen bonds, which are the types of bonds responsible for pairing the two strands of DNA, this process is known as denaturation of DNA.
The DNA is extremely stable, due to a large number of bonds (hydrogen bonds) that form between the two strands. If the temperature decreases, these bonds will begin to recompose, until the DNA returns to its original state
<span>Adjacent-1 segregation and adjacent-2 segregation.
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Fuel cells can make an electricity from a simple electrochemical
reaction in which oxygen and hydrogen combine to form water. There are several
different types of fuel cell but they are all based around a central design
which consists of two electrodes, a negative anode and a positive cathode.
These are separated by a solid or liquid electrolyte that carries electrically
charged particles between the two electrodes. A catalyst, such as platinum, is
often used to speed up the reactions at the electrodes. Fuel cells are
classified according to the nature of the electrolyte. Every type needs
particular materials and fuels and is suitable for any applications. The
article below uses the proton exchange membrane fuel cell to illustrate the
science and technology behind the fuel cell concept but the characteristics and
applications of the other main designs are also discussed. Proton Exchange Membrane Fuel Cells (PEMFC)
The hydrogen ions permeate across the electrolyte to the
cathode, while the electrons flow through an external circuit and provide
power. Oxygen, in the form of air, is supplied to the cathode and this combines
with the electrons and the hydrogen ions to produce water. These reactions at
the electrodes are as follows:
Anode: 2H24H+ + 4e-
Cathode: O2 + 4H+ + 4e- 2H2O
Overall: 2H2 + O22H2O + energy
PEM cells operate at a temperature of around 80°C. At this
low temperature the electrochemical reactions would normally occur very slowly
so they are catalysed by a thin layer of platinum on each electrode.
0% considering you didn't insert the question...
Answer:
A. a developing nation
Explanation:
Age pyramids are the age structure diagrams that represent the number and proportion of people at each age in a population. The base of the age pyramids represents the population in pre-reproductive age which is from 0 to 10 years. The overall shape of an age pyramid indicates if the population is increasing, stationary, or shrinking.
The age structure diagram for a developing nation has a broad base that tapers quickly towards the top. This means that a larger percentage of the population is in the pre-reproductive age group and reproductive age group with a smaller percentage of the population in the post-reproductive age. These countries have a great chance of future population growth.
