PORTAGE LEARNING BIOCHEM MODULE 4
EXAM COMPREHENSIVE EXAMINATION TEST
2026 SOLVED QUESTIONS ANSWERS GRADED
A+
◉ Why do cells use the urea cycle?
Answer: To process and excrete nitrogen, preventing its toxic build
up
◉ Define chemiosmotic theory
Answer: the theory that most of the ATP synthesised during
respiration is during oxidative phosphorylation
◉ Define carbon skeleton
Answer: Carbon portion of amino acids, structural framework
◉ What do the carbon, hydrogen and oxygen atoms yield?
Answer: Acetyl-CoA
◉ How are other atoms, nitrogen and sulfur, handled?
Answer: In catabolic process by specific processes and enzymes
, ◉ What is NH4+ produced by?
Answer: Oxidative deamination
◉ Define deamination and what it results in
Answer: Removal of amine functional group in the degradation of
amino acids, results in ammonium NH4+, then the NH4+ and carbon
atoms undergoing different catabolic pathways
◉ What happens to the carbon skeleton of amino acid after is it
separated from NH4+?
Answer: Carbon skeleton becomes Acetyl-CoA then ATP
◉ List the diagram of protein catabolism (7)
Answer: Proteins>amino acids>oxidative deamination (>NH4+ urea
cycle)>carbon skeleton>Acetyl-CoA>ATP
◉ Define urea cycle
Answer: Four-step cyclic process that converts NH4+ to urea, which
is then excreted from body
◉ Where is the urea cycle located?
Answer: Liver and kidneys mostly
EXAM COMPREHENSIVE EXAMINATION TEST
2026 SOLVED QUESTIONS ANSWERS GRADED
A+
◉ Why do cells use the urea cycle?
Answer: To process and excrete nitrogen, preventing its toxic build
up
◉ Define chemiosmotic theory
Answer: the theory that most of the ATP synthesised during
respiration is during oxidative phosphorylation
◉ Define carbon skeleton
Answer: Carbon portion of amino acids, structural framework
◉ What do the carbon, hydrogen and oxygen atoms yield?
Answer: Acetyl-CoA
◉ How are other atoms, nitrogen and sulfur, handled?
Answer: In catabolic process by specific processes and enzymes
, ◉ What is NH4+ produced by?
Answer: Oxidative deamination
◉ Define deamination and what it results in
Answer: Removal of amine functional group in the degradation of
amino acids, results in ammonium NH4+, then the NH4+ and carbon
atoms undergoing different catabolic pathways
◉ What happens to the carbon skeleton of amino acid after is it
separated from NH4+?
Answer: Carbon skeleton becomes Acetyl-CoA then ATP
◉ List the diagram of protein catabolism (7)
Answer: Proteins>amino acids>oxidative deamination (>NH4+ urea
cycle)>carbon skeleton>Acetyl-CoA>ATP
◉ Define urea cycle
Answer: Four-step cyclic process that converts NH4+ to urea, which
is then excreted from body
◉ Where is the urea cycle located?
Answer: Liver and kidneys mostly
