Electrocardiograph (EKG or ECG) technicians operate equipment that measures, monitors, and graphically traces the electrical activity of the heart. Physicians use the graph (electrocardiogram/EKG/ECG) to diagnose and monitor patients' heart problems.
Answer:
A reaction that joins the nuclei of two atoms into one
Explanation:
Think of the words "nuclear fusion".
Nuclear = "relating to a nucleus"
Fusion = "joining"
So, nuclear fusion is the joining of two nuclei into one.
A and B are wrong, because chemical reactions involve electrons.
D is wrong, because the splitting of a nucleus is fission.
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.
Answer:
The correct option is D. New cells are produced from existing cells is a part of the cell theory.
Explanation:
Cell theory can be described as one of the earliest theories of biology which states that cells are the basic unit of life out of which all living things are made. The modern cell theory comprises of three main parts:
- All the living forms of life are manufactured from cells.
- Cells are the main unit which are involved in properly organizing a living organism.
- New cells arise from pre-existing cells.
Correct answer: A). The enzyme influences the speed of change from substrate to product
The enzymes are the biological catalyst that speed up the rate of chemical reactions by decreasing the activation energy of the reaction pathway.
They increase the speed of change of substrate to the product and it remains unchanged in the reaction. Hence, it can be used again and again.
Enzymes are highly specific in nature, only a specific substrate binds to the enzyme's active site. Hence, a particular enzyme is required to catalyze a reaction.
