1. The carbon-dioxide increases in atmosphere by fossil-fuels, decaying-dead, automobiles etc. and when animals or plant die they get buried and carbon content increases under the ground.
2. Greenhouse gas are those gases which trap heat in the atmosphere and maintain the temperature of the earth.
3. Diamond and graphite are solid forms of carbon.
4. Dry ice is the carbon as liquid.
5. Autotrophs make simple sugar glucose via photosynthesis and this sugar is used by heterotrophs as a substrate for respiration in the presence of oxygen.
Explanation:
When the fuels from automobiles, fossil-fuel, dead decaying organism release carbon in the atmosphere, the increase in carbon dioxide is the cause of global warming.
Greenhouse gases absorb the infrared radiations from the earth's surface and reradiate it back to the atmosphere. In short greenhouse gases allow sun's rays to pass through and maintain the earth's temperature otherwise the earth will become too cold to sustain lives.
The answer is D. The natural selection is a theory which illustrates the gradual process of evolution in the population due to the change of environment. The key point is the mutation (variation) exists in the population before the environment changing. For C, if the environment does not change, though the adaptation is useful to environment, it will not be selected. Because the organisms without the adaptation will not die.
<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.
D would be the correct answer
