Answer:
DNA
Explanation:
The nucleus is a central placed organelle in eukaryotic cells. It is said to contain the "blueprint of life" known as the DNA. The DNA is a structure located in the nucleus of the cell that encodes information necessary for the growth and development of the organism.
This information encoded by the deoxyribonucleic acid (DNA) of the cell includes how the organism will reproduce, hence, DNA is called the blueprint of life.
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.
In order for gas to leave a planet it needs to be hot enough and to overcome the planets gravity. The outer planets are colder and are very big compared to earth.
You should get rid of any distractions so you can focus.
Answer: Option B.
Neural crest and peripheral nervous system.
Explanation:
Neural crest are bilateral paired cells of the neural tube that arise from the ectoderm layer of the embryo. Thesescells move to different part of the body and differentiate into various cell types like melanocytes,cartilage and bone, smooth muscle, craniofacial, neurons, gangalia e.t.c. The neural crest running through neural tube develop into peripheral nervous system after birth. Peripheral nervous system consist of neurons and gangalia outside the nervous system The peripheral nervous system connect the central nervous system to organs, skin and limbs.
