Oxygen-16 and Carbon-12 are stableisotopes of elements O and C respectively. Hence, they do not have half-lives. But Carbon-14 andUranium-238 are radioactive isotopes. Among them Carbon-14 has relatively short half-life as about 5730 years while Uranium-238 has a long half-life as about 4.5 billion years.
Answer is. uranium-238
Answer:
The correct is B Hormones are chemical signals between cells transported in blood or hemolymph.
Explanation:
Hormones are called chemical messenger of the cell because they transmit chemical information from one cell to the target cell and regulating the functioning of that target cell by activating specific proteins related to the functioning of that target cell.
Hormone is secreted from its source gland such as Pituitarygland, thyroid gland,adrenal gland.After being secreted hormones are transported via the blood stream to the target cell and binds to receptor of that target cell thus allowing the target cell to exert its biological function.
They are like that because they can't always be faulty and may have at least some spark of truth to this theory also as stated earlier a theory in scientific terms is just an observation so it can't really be turned down hence theory.
C. Mutualistic relationship
Flowers and hummingbirds have a mutualistic relationship where both benefit. Flowers produce food in the form of nectar (sugar and water) to attract hummingbirds which, in turn, move pollen for the plant (pollination).
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