<span>LD
means lethal dose. LD50 is the amount of a material, administered at once to
cause the death of half (50%) of a group of test organisms. A test which shows that LD50 of a certain
chemical is 20 mg per kg means that 20 milligrams of that chemical for every 1
kilogram body weight of the test animal when administered in one dose, causes
the death of 50% of the test group.</span>
Answer:
The basal cell layer is the innermost layer of the epidermis, comprising the keratinocytes and melanocytes. Keratinocytes play an important role in providing skin structure and in functioning of the immune system. Melanin is a pigment produced by melanocytes, and is responsible for providing the skin color.
Answer:
Concentrations of carbon dioxides are rising mainly due to energy-burning fossil fuels. Fossil fuels such as carbon or oil include carbon plants which, over the years, are photosynthesized in the atmosphere; in a few hundred years we have returned this carbon to the air
Explanation:
Even fundamental human functions — eating inhalation and digestion — generate CO2. In the life cycles of the earth, it is an essential chemical. Active plants and trees are absorbing CO2 and turning it into food with sunlight and water. There are problems when more CO2 is emitted than is absorbed by our vegetation. Activities to produce high carbon dioxide include:
- Consuming electricity: Fossil fuels emit CO2, with coal emitting twice as much gas as oil. Worldwide, 85% of energy is generated by fossil fuels. As China and India continue to industrialize, the number of coal-burning plants will rise. Today, power generation represents 41 percent of CO2 emissions in the United States.
- Transportation: Locomotive is the second greatest source for U.S. CO2 emissions for business or pleasure. Travel is also a factor internationally. A cruise ship study indicated that holidays at sea produce 12 times more CO2 than on land. 41,000 tonnes of CO2 was generated at Denmark's 11-day worldwide Copenhagen Conference on Climate Change. U.S. representatives alone produced sufficient CO2 to fill 10,000 Olympic pools.
- Building: Manufacturing produces large amounts of CO2, yet only represents 2% of US emissions. The most serious offenders are the manufacture of iron and steel and cement. These businesses use huge amounts of thermal energy to turn commodities into building products.
- Deforestation: Trees are powerful organisms that absorb CO2 from the air and remove it. It stops the process by cutting them down. While deforestation is a tiny source of increasing CO2 in the U.S., 20 percent of global CO2 emissions are due to forest loss. Fuel-burning trees and natural forest material breakdown also generate CO2.
Answer:
"Ionosphere and Exosphere" is the right response.
Explanation:
- The ionosphere seems to be the interface through which the Northern side lights originally come, or perhaps the Aurora Borealis. This same radioactivity including its sun throughout the ionosphere ionized particles the particulates emitting the logo lighting system of Aurora.
- The exosphere, having started from five hundred kilometers, would be the outermost part of that same thermosphere. This same exosphere appears to contain slightly heavier gasses including such helium.
