There are many lines of evidence which clearly show that the atmospheric CO2<span>increase is caused by humans. The clearest of these is simple accounting - humans are emitting CO2 at a rate twice as fast as the atmospheric increase (natural sinks are absorbing the other half). There is no question whatsoever that the CO2 increase is human-caused. This is settled science.</span>
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True.
Explanation:
in the early 1900s development of Salvarsan, an arsenic-based drug to treat syphilis.
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Animals and plants need nitrogen to build amino acids in proteins, which are the building blocks of life. Unlike oxygen, nitrogen cannot be absorbed directly from the air by animals and plants.
Explanation:
Answer:
Although more offsprings are produced by the process of external fertilization but the process of internal fertilization is more efficient as compared to external fertilization. This is because, in external fertilization, it is more difficult for the sperm to find the egg and fertilize it. Even after fertilization, it might be that the zygote gets eaten up by a predator. There are none such risks in internal fertilization. The zygote is protected during the internal fertilization which makes this process more efficient.
By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.
