Answer:
hypertonic then isotonic and hypotonic
Explanation:
Answer:
<em>The correct option is d) once the electrical impulse reaches a certain level of intensity (its threshold), it fires and moves all the way down the axon without losing any intensity.</em>
Explanation:
In the field of biology, the all-or-nothing law can be described as a principle which focuses on the strength with which a nerve or muscle fibre responds to a particular stimulus, this strength being independent of the strength of the stimulus. The functioning of the impulse is just like the trigger of a gun. The more the force of a stimulus, the more will be the intensity of the nerve impulse.
Answer:
0.8 and 0.2
Explanation:
Hardy Weinberg law states that the allele frequency of the population remain stable from one generation to next generation if no natural selection, drift or mutation occurs in the population.
Let p and q be the dominant and recessive frequency of the population respectively.
The dominant phenotype means p² = 0.64
p = 0.8
and we known that p + q = 1, in hardy Weinberg equilibrium.
0.8 + q = 1.
q = 0.2
Thus, the dominant allele is 0.8 and recessive allele is 0.2.
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.
