In most plant cells,most enzymes have their optimum activity at: (in $^\circ C$)

Enzymes are proteins. Proteins are long chains of amino acids linked to each other by peptide bonds. Amino acids have many functional groups in their structure. Many of these functional groups are ionisable. As they are weak acids and bases in chemical nature,this ionisation is influenced by the $pH$ of the solution. For many enzymes,activity is influenced by the surrounding $pH$. This is depicted in the curve below. Explain briefly.

Which enzyme is associated with oxidation and reduction reactions in a cell?

Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Transferases	$(P)$ Maltase
$(2)$ Hydrolases	$(Q)$ Hexokinase
$(3)$ Lyases	$(R)$ Fructose isomerase
$(4)$ Isomerases	$(S)$ Aldolase

Most of the enzymes work at an optimum temperature between . . . . . . .

$A$ - Activity of an enzyme can be affected by a change in environmental conditions.
$R$ - These factors regulate the activity of the enzyme.