Answer: Over 4 billion years ago
Explanation: The chemical reactions between carbon and water is said to bring about life according to scientists. These reactions builds largely upon four families of chemicals (lipids, carbohydrates, amino acids, and nucleic acids).
However, the actual time of life on Earth has varying speculations from different scientists in fields of study (such as molecular biology, chemistry, oceanography, etc).
Furthermore, microfossils within hydrothermal-vent precipitates dated from 3.77 to 4.28 billion years is presumed to inhabit the oldest record of life on Earth. Hence, which is presumed to have occurred after ocean formation 4.4billion years ago.
Thus, the actual date of the chemical reactions that brought about life is not rigid, but presumed to have occurred over 4billion years ago (according to research).
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The answer is B. They cannot produce enough heat to keep their bodies warm.
You move the decimal to the right →
Answer:
A, B and C may be true
Explanation:
The three-dimensional structure (3D) of a protein, also known as tertiary structure, is critical to its function. In general, the 3D protein structure consists of alpha-helix and beta-sheets (secondary structures) associated through disordered coiled-coil regions. Genetic mutations may cause modifications in the 3D protein structure by modifying amino acids that are added to the growing polypeptide chain during the process of translation. In consequence, the relationships among amino acids (i.e., the intermolecular attractive forces that hold them together) may also be altered by these mutations. In general, mutations that generate amino acid changes at the active site of the enzyme will have a deleterious effect, thereby decreasing or inactivating protein function. However, there are situations where a mutation may be beneficial and can eventually increase the rate of reaction of a protein.
