When acting as a respiratory substrate,which of the following would be broken down to acetyl Co-$A$?

Choose the incorrect sentence$(s)$ regarding the amphibolic pathway.
$(1)$ Carbohydrates are generally used as substrates for respiration.
$(2)$ Fatty acids can first be degraded into acetyl $CoA$,which enters the respiratory pathway.
$(3)$ In the case of proteins,they are first broken down into amino acids,which are later converted into pyruvic acid and enter the respiratory pathway.
$(4)$ The respiratory pathway is involved in both anabolism and catabolism.
$(5)$ Glycerol would enter the pathway after being converted to $PGAL$.

The maximum amount of energy / $ATP$ is released during the oxidation of which of the following?

Write the functional characteristics of endodermal cells.

The link between glycolysis,the Krebs cycle,and the $\beta$-oxidation of fatty acids/carbohydrate and fat metabolism is ...........

The following figure shows an amphibolic pathway. What are $P$,$Q$,and $R$?