Answer:
21. Erosion causes physical changes. For example - Land degradation, deforestation.
20. B statement is closely related to climate.
hope it helps!
Yes its worth the trouble. We breathe in Oxygen and give out CO2. We burn wood. Our bikes rust.
The bond formed between two or more electrons of different atoms is called a COVALENT BOND.
Water molecules forming hydrogen bonds with one another. The partial negative charge on the O of one molecule can form a hydrogen bond with the partial positive charge on the hydrogens of other molecules. Water molecules are also attracted to other polar molecules and to ions.
Answer:
A). The complementary shapes of an enzyme and a substrate.
Explanation:
The Lock-and-key mechanism was proposed by Emil Fischer for the first time and characterized as the metaphor which helps in elucidating the specificity of the enzymatic reactions. In this metaphor, the lock is described as the enzyme while 'key' is characterized as the substrate which the enzyme acts upon. If the key is not appropriately sized, it will not fit into the active site i.e. the keyhole of the lock or enzyme and reaction will not take place. Thus, <u>option A</u> is the correct answer.
