Answer:
A <u><em>receptor</em></u> is a protein that recognizes and responds to a signal.
Explanation:
A receptor is a protein molecule present on the cells on which the signalling molecules can bind and generate a physiological response. Some receptor molecules can also respond to Sun and light. Each type of cell has specific receptors molecules and hence can respond to specific signals. The receptor molecules hence tend to receive signals for a cell. Molecules such as hormones bind to the receptors.
Hydrogen bonds i hope that helps
Answer: <u>Option A, OPEC
</u>
Explanation: Around 80 percent of oil production was accounted by OPEC in the year 2018. It is an organization of fifteen countries, which contain majority of oil reserves. Mainly the oil comes from the middle-eastern countries; namely Kuwait, Iran, Iraq, Qatar, etc.
United Nations and European Union hold very minute share in world's oil production. Exxon's share is also less than ten percent.
