Which of the following is utilized first in respiration?

The common phase between aerobic and anaerobic respiration is called:

In which of the following steps of glycolysis is $ATP$ utilized?

Glycolysis:
$I$. Causes partial oxidation of glucose (one molecule) to form $2$ molecules of pyruvic acid and $2$ $ATP$ as net gain.
$II$. Takes place in all living cells.
$III$. Uses $2$ $ATP$ at two steps.
$IV$. Scheme was given by Gustav Embden,Otto Meyerhof,and $J$. Parnas.
Choose the correct option containing appropriate statements from the above.

During glycolysis,which molecule acts as the electron acceptor during the oxidation of glyceraldehyde$-3-$phosphate?

Glycolysis is a $........$ process and is completed in $......$ steps.