Which disaccharide is formed by α-1,4-glycosidic linkage between glucose molecules?
Answer: C
Maltose consists of two glucose units linked by an α-1,4-glycosidic bond. Sucrose contains glucose and fructose, lactose contains glucose and galactose, and trehalose has an α-1,1-glycosidic linkage.
Q.42Easy
Which carbohydrate is a non-reducing sugar that cannot undergo mutarotation?
Answer: B
Sucrose is a non-reducing disaccharide formed by α-1,2-glycosidic linkage between C1 of glucose and C2 of fructose, blocking both anomeric carbons. It cannot mutarotate or act as a reducing sugar. Other options are reducing sugars with free anomeric carbons.
Q.43Easy
Which of the following carbohydrates is classified as a pentose sugar?
Answer: A
Ribose is a 5-carbon (pentose) sugar, while glucose, galactose, and fructose are hexoses (6-carbon sugars).
Q.44Easy
In glycolysis, the conversion of glucose-6-phosphate to fructose-6-phosphate is catalyzed by which enzyme?
Answer: B
Phosphoglucose isomerase catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate in the second step of glycolysis.
Q.45Easy
Which enzyme is the rate-limiting step of glycolysis and is inhibited by ATP and citrate?
Answer: B
Phosphofructokinase-1 (PFK-1) catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate and is subject to allosteric inhibition by ATP and citrate.
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Q.46Easy
What is the net yield of ATP from the anaerobic metabolism of one molecule of glucose?
Answer: A
Anaerobic glycolysis produces 4 ATP molecules but consumes 2 ATP, resulting in a net gain of 2 ATP per glucose molecule.
Q.47Easy
Which of the following is a reducing sugar?
Answer: C
Maltose is a reducing sugar because it has a free anomeric carbon. Sucrose and trehalose are non-reducing sugars as both anomeric carbons are involved in glycosidic bonds.
Q.48Easy
Which of the following carbohydrates is a ketohexose?
Answer: A
Fructose is a ketohexose (6-carbon ketone sugar), while glucose, galactose are aldohexoses, and ribose is a pentose.
Q.49Easy
The disaccharide formed by α-glucose and β-fructose joined by α-1,2-glycosidic bond is:
Answer: C
Sucrose is composed of glucose and fructose linked by α-1,2-glycosidic bond. Maltose has α-1,4 bond between two glucose molecules.
Q.50Easy
Which enzyme catalyzes the reversible conversion of glucose-6-phosphate to fructose-6-phosphate?
Answer: B
Phosphoglucose isomerase catalyzes the interconversion of glucose-6-phosphate and fructose-6-phosphate in glycolysis.
Q.51Easy
The optical rotation of freshly prepared glucose solution gradually decreases and reaches equilibrium. This phenomenon is called:
Answer: A
Mutarotation is the spontaneous interconversion between α and β anomers of glucose at the anomeric carbon until equilibrium is reached.
Q.52Easy
Which of the following carbohydrates does NOT undergo glycolysis?
Answer: C
Cellulose is a β-1,4-linked glucose polymer that humans cannot digest due to lack of cellulase enzyme. It cannot enter glycolysis.
Q.53Easy
Which of the following is NOT a component of a triglyceride molecule?
Answer: C
Triglycerides consist of glycerol and three fatty acids connected by ester bonds. Phosphate groups are found in phospholipids, not triglycerides.
Q.54Easy
What is the primary function of HDL cholesterol in the body?
Answer: B
HDL (High-Density Lipoprotein) is known as 'good cholesterol' because it transports cholesterol from peripheral tissues back to the liver for degradation and excretion.
Q.55Easy
Omega-3 fatty acids are beneficial for human health because they:
Answer: C
Omega-3 polyunsaturated fatty acids (found in fish, flaxseed) have anti-inflammatory properties and support heart health by reducing triglycerides and blood pressure.
Q.56Easy
Which lipid type is essential for maintaining the structural integrity of cell membranes?
Answer: A
Cell membranes are composed of a phospholipid bilayer with embedded cholesterol molecules that regulate membrane fluidity and maintain structural integrity.
Q.57Easy
What is the difference between saturated and unsaturated fatty acids in terms of their chemical structure?
Answer: B
Saturated fatty acids have all single bonds between carbon atoms (straight chain), while unsaturated fatty acids have one or more C=C double bonds (kinked structure).
Q.58Easy
Which of the following lipids is NOT a structural component of cell membranes?
Answer: D
Triacylglycerols are storage lipids found primarily in adipose tissue. Phosphatidylcholine, cholesterol, and sphingomyelin are major components of cell membranes.
Q.59Easy
The rate-limiting enzyme in de novo fatty acid synthesis is:
Answer: A
Acetyl-CoA carboxylase catalyzes the formation of malonyl-CoA from acetyl-CoA, which is the first committed and rate-limiting step in fatty acid synthesis.
Q.60Easy
Beta-oxidation of fatty acids occurs primarily in which cellular compartment?
Answer: C
Most fatty acids undergo beta-oxidation in the mitochondrial matrix. However, very long chain fatty acids (>20 carbons) are initially oxidized in peroxisomes.
