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.
The correct answer is the interphase.
The cell cycle consists of three phases: the interphase (G1, S, G2) the mitotic (M) phase, and cytokinesis. <span>The first checkpoint of the cell cycle is G1 checkpoint which is between G1 and S phase when cell checks its size, nutrients, molecular signals, DNA integrity. The second checkpoint is G2, just before the mitotic phase, when cell checks DNA integrity and DNA replication. Those two checkpoints are the ones before division, other like M checkpoint is during the mitosis.</span>
Answer:
The correct answer is a. Reduction in species diversity
Explanation:
In habitat fragmentation, the large area of forest is divided into many smaller patches which reduce the area of habitat for species live there. This Fragmentation of habitat occurs mainly due to human activities like making highways and roads in the area.
This separates species member from each other which reduces the gene flow between that which can lead to inbreeding depression in a species and extinction of species can occur.
Cutting trees and human activities can alter the environment negatively which can cause extinction of some species that reduce species diversity. So the correct answer is a.
The correct answer is option A
Phloem is a vascular tissue which helps in the transportation of sugars from the source tissue( where it is formed). The carbohydrates or sugars are transported from the chloroplast of the plant to the other parts of the plant. Other molecules along with carbohydrates are also transported with the help of phloem.
Answer:
Consumer
Explanation:
A consumer is an organism that eats another organism in order to survive. If a fly eats a deer or any rotting meat it is a consumer.
