Answer:
A.The hole in the ozone layer
Explanation:
• Montreal protocol is an international treaty that was signed to control the use of substances that are resulting in the depletion of the ozone hole.
This treaty was signed in the year 1987 and became effective form 1989.
• Since the time that this treaty has come into force, there has been a significant improvement in the ozone hole that was observed over Antarctic as it's size has decreased.
• This improvement has been possible because the treaty helped to phase out chemicals such as chlorofluorocarbons, carbon tetrachloride, etc. that are responsible for ozone hole depletion.
It's some change in the conditions around the organism, which the organism can detect and respond to. A change in temperature, more light, or something physically poking the organism are examples.
Proteins are the macromolecules made of hundreds of amino acids. Proteins are most varied class of biological molecules and show the greatest variety of structures. Many have detailed three-dimensional folding patterns that result in a compact form, but others do not fold up at all and they are in random conformations. The function of proteins depends on their structure.
The secondary structure of protein fold together to form the 3D arrangement of a polypeptide chain that results into Tertiary structure which is a functional protein.
