Answer to Question 1
An alternative to burning hydrogen in conventional internal combustion engines uses hydrogen in fuel cells to produce electricity and power the vehicle with an electric motor. Fuel cells are devices in which hydrogen or some other fuel is chemically recombined with oxygen in a manner that produces an electrical potential rather than initiating burning. Emissions consist solely of water and heat Because fuel cells create much less waste heat than conventional engines do, energy is transferred more efficiently from the hydrogen to the vehicleat a rate of 45 to 60, versus the 20 for current combustion-engine vehicles. To power a vehicle, hundreds of fuel cells are combined into a fuel cell stack. The vehicle must also include a hydrogen storage device, a cooling system (fuel cells also generate heat), and a device to force oxygen into the fuel cells.
Answer to Question 2
Ecosystem management comprises several main principles in that it looks at ecosystems on both small and large scales. Ecosystem management is dependent on good management that preserves the range of possible landscapes in an ecosystem instead of allowing one type to take over the area.
Color-enhanced scanning electron micrograph of HIV virus (red) infecting T-helper cells (green).
Red cells have a biconcave shape.
Reed-Sternberg cells: Bilobed nucleus coupled with the prominent nucleoli gives this cell the ...
Nuclear power
Staphylococcus aureus cells (yellow) stuck in mucus secreted by human nasal epithelial cells.