Which of the following statements are correct from given statements?

(i) Glucose is the favoured substrate for respiration. All carbohydrates are usually first converted into glucose before they are used for respiration.

(ii) Other substrates like fats, proteins can also be respired but they do not enter the respiratory pathway at the first step.

(iii) If fatty acids were to be respired they would first be degraded to acetyl CoA and enter the pathway.

(iv) Glycerol would enter the pathway after being converted to PGAL.

(v) The proteins would be degraded by proteases and the individual amino acids and it enter the pathway at some stage within the Krebs’ cycle or even as pyruvate or acetyl CoA.

(vi) Because the respiratory pathway is involved in both anabolism and catabolism it consider as an amphibolic pathway rather than as a catabolic one.