What is the significance of the Krebs cycle?

Assertion $A$: Carbohydrates are the primary source of energy in living organisms.
Reason $R$: Glucose is the common substrate used in respiration.
Which option is correct for Assertion $A$ and Reason $R$?

Assertion : The inner membrane of mitochondria contains systems involving electron transport.
Reason : The mitochondrial matrix contains enzymes of Kreb's cycle.

Match the name of the scientist or discovery with its corresponding pathway or process:

$A$. $PPP$ (Pentose Phosphate Pathway)	$i$. Kuhne pathway
$B$. Demonstration of fermentation	$ii$. Kreb's cycle
$C$. $TCA$ cycle	$iii$. Warburg-Dickens pathway
$D$. Glycolysis	$iv$. Embden-Meyerhof-Parnas pathway

Choose the correct matching sequence:

The process of phosphorylation takes place in

The given schematic diagram shows three main biosynthetic pathways of aerobic respiration in three boxes. The arrows indicate reactants or products. Arrows $4, 8,$ and $12$ all represent -