BIO024: SAS 9
Question 1
Which component of the digestive system is primarily responsible for the physical breakdown (churning) of dietary triacylglycerols (TAGs) into chyme before chemical digestion?
Mouth
Stomach
Small Intestine
Large Intestine
Question 2
The arrival of acidic chyme in the small intestine triggers the release of which hormone to stimulate gallbladder contraction and bile release?
Insulin
Epinephrine
Cholecystokinin (CCK)
Glucagon
Question 3
What is the primary role of bile salts during the digestion of dietary lipids in the small intestine?
Hydrolyze ester bonds in triacylglycerols
Emulsify lipid droplets into smaller particles and micelles
Transport free fatty acids across the blood-brain barrier
Phosphorylate glycerol into glycerol 3-phosphate
Question 4
What are the two primary chemical products resulting from the action of pancreatic lipase on triacylglycerols in the small intestine?
Glycerol and 3 acetyl-CoA molecules
Glucose and pyruvate
Monoacylglycerol and 2 free fatty acids
Acetoacetate and beta-hydroxybutyrate
Question 5
Following absorption into intestinal mucosal cells, digested lipids are repackaged into which class of lipoproteins for transport through the lymphatic system?
Very-Low-Density Lipoproteins (VLDL)
High-Density Lipoproteins (HDL)
Chylomicrons
Low-Density Lipoproteins (LDL)
Question 6
Which signaling molecule directly activates Hormone-Sensitive Lipase (HSL) via phosphorylation to initiate triacylglycerol mobilization in adipose tissue?
Cyclic AMP (cAMP)
Insulin
Citrate
Malonyl-CoA
Question 7
What are the two enzymatic steps required to convert mobilized glycerol into dihydroxyacetone phosphate (DHAP) for entry into glycolysis or gluconeogenesis?
Glycerol kinase followed by glycerol 3-phosphate dehydrogenase
Acyl-CoA synthetase followed by thiolase
HMG-CoA synthase followed by HMG-CoA lyase
Pyruvate carboxylase followed by PEPCK
Question 8
Fatty acid activation occurs on the outer mitochondrial membrane and requires how much energy expenditure?
No ATP consumed
Equivalent of 1 ATP (1 high-energy bond)
Equivalent of 2 ATPs (2 high-energy phosphate bonds)
4 ATPs
Question 9
Which carrier molecule is specifically required to shuttle long-chain fatty acyl groups across the inner mitochondrial membrane into the mitochondrial matrix?
Albumin
Carnitine
Citrate
Acyl Carrier Protein (ACP)
Question 10
What is the correct chronological sequence of the four repetitive reactions in the beta-oxidation pathway?
Hydration > Dehydrogenation > Thiolysis > Dehydrogenation
Dehydrogenation > Hydration > Dehydrogenation > Thiolysis
Thiolysis > Dehydrogenation > Hydration > Condensation
Condensation > Reduction > Dehydration > Reduction
Question 11
For each single turn of the Beta-oxidation pathway processing a saturated fatty acid, what are the net yield products?
1 Acetyl Coa, 1 FADH2, 1 NADH
2 Acetyl CoA, 2 FADH2, 2 NADH
1 Malonyl-CoA, 1 NADH, 1 ATP
1 Propionyl CoA , 1 GTP, 1 FADH2
Question 12
How many turns of Beta-oxidation and how many acetyl-CoA molecules are produced during the complete degradation of Palmitic acid (a 16-carbon saturated fatty acid)?
8 turns; 8 acetyl-CoA
7 turns; 8 acetyl-CoA
16 turns; 16 acetyl-CoA
7 turns; 7 acetyl-CoA
Question 13
What two additional helper enzymes are specifically required for the complete Beta-oxidation of unsaturated fatty acids compared to saturated fatty acids?
Pyruvate dehydrogenase and citrate synthase
Epimerase and cis-trans isomerase
Acyl-CoA synthetase and glycerol kinase
HMG-CoA reductase and acetyl-CoA carboxylase
Question 14
Where does lipogenesis (fatty acid biosynthesis) primarily occur within the cell, and what multienzyme complex catalyzes its chain elongation steps?
Mitochondrial matrix; Carnitine palmitoyltransferase
Cytosol; Fatty Acid Synthase (FAS) complex
Endoplasmic reticulum; HMG-CoA lyase
Nucleus; RNA polymerase
Question 15
How is acetyl-CoA transported from the mitochondrial matrix into the cytosol for lipogenesis?
Direct diffusion through mitochondrial pores
As Acyl-carnitine via the carnitine translocase
As Citrate via the Citrate-Malate shuttle system
Bound to albumin in the intracellular fluid
Question 16
Compared to glucose, how much energy do fatty acids yield on an equal-mass basis?
Half as much energy per gram
Equal energy per gram
2.5 times as much energy per gram
10 times as much energy per gram
Question 17
Under what metabolic conditions does ketogenesis become significantly elevated in the liver?
High-carbohydrate, low-fat diet in a resting state
Upregulated glycogenesis in the postprandial state
Carbohydrate-lipid imbalance such as starvation, prolonged fasting, or uncontrolled diabetes
Excess insulin secretion following a meal
Question 18
Which of the following compounds is NOT classified as a ketone body?
Acetoacetate
Beta-Hydroxybutyrate
Acetic acid
Acetone
Question 19
What is the correct sequence of reaction types during the hepatic synthesis of ketone bodies (ketogenesis)?
Dehydrogenation > Hydration > Dehydrogenation > Thiolysis
Condensation > Condensation > Chain Cleavage > Hydrogenation
Carboxylation > Reduction > Dehydration > Thiolysis
Phosphorylation > Oxidation > Isomerization > Cleavage
Question 20
Why does the brain utilize ketone bodies as an alternative energy source during prolonged starvation or fasting?
The brain lacks enzymes for glycolysis
Long-chain fatty acids cannot cross the Blood-Brain Barrier (BBB)
Ketone bodies produce more ATP than glucose per molecule
Insulin prevents glucose uptake in the brain
Question 21
Which laboratory measurement threshold indicates that blood ketone levels have exceeded the renal reabsorption limit, leading to ketonuria?
1 mg/100 mL
5 mg/100 mL
20 mg/100 mL
70 mg/100 mL
Question 22
What clinical metabolic complication is characteristic of uncontrolled Type 1 Diabetes Mellitus due to absolute insulin deficiency?
Severe respiratory alkalosis
Diabetic Ketoacidosis (DKA) / Metabolic Acidosis
Hyperinsulinemic hypoglycemia
Hypovertical chylomicronemia
Question 23
Why do patients with uncontrolled diabetes frequently exhibit hypertriacylglycerolemia (elevated blood VLDL and chylomicrons)?
Overactivity of pancreatic lipase in the GI tract
Decreased synthesis and activity of Lipoprotein Lipase (LPL) in capillary beds
Inhibition of HSL in adipocytes
Excessive clearance of HDL by the kidneys
Question 24
Why are linoleic acid and linolenic acid classified as essential fatty acids in human nutrition?
Humans cannot oxidize fatty acids with more than 10 carbons
Human desaturase enzymes can only introduce double bonds between C-4/C-5 and C-9/C-10
They are destroyed by stomach acid during digestion
They can only be synthesized in liver mitochondria during ketogenesis
Question 25
Which four B-complex vitamins are collectively required as coenzymes for the integrated pathways of beta-oxidation, ketogenesis, and lipogenesis?
Thiamine , Riboflavin , Niacin, Pyridoxine
Niacin, Riboflavin, Pantothenic acid, Biotin
Folate, Cobalamin, Biotin, Thiamine
Ascorbic acid, Calciferol, Niacin, Riboflavin