Exams › NEET › Biology › Biomolecules
95 questions with worked solutions.
Q1. Coenzymes NAD and NADP contain the vitamin
Answer: Niacin
NAD and NADP are derived from niacin, also called vitamin B3, specifically its nicotinamide component. This vitamin is required to synthesize these electron-carrying coenzymes.
Q2. All the reactions in glycolysis are reversible except
Answer: Fructose - 6 -phosphate to fructose- 1,6 -diphosphate.
Most glycolytic reactions are near-equilibrium and can run in either direction. The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate is strongly exergonic and is essentially irreversible under cellular conditions.
Answer: Liver and muscles
Glycogen is the storage form of glucose in animals, and it is mainly stored in the liver and skeletal muscles. The liver helps maintain blood glucose, while muscles use their glycogen for their own energy needs.
Q4. The \( 3^{\prime}-5^{\prime} \) phosphodiester linkages inside a polynucleotide chain serve to join
Answer: One nucleotide with another nucleotide
A 3′-5′ phosphodiester bond forms between the phosphate of one nucleotide and the 3′ hydroxyl of the next sugar, creating the backbone of DNA or RNA. Therefore, it joins one nucleotide to another nucleotide.
Q5. Which among the following is correctly categorized?
Answer: Troponin and Myosin \( \rightarrow \) Complex proteins in striated muscles
Troponin and myosin are both proteins associated with the contractile apparatus of striated muscle, so this pairing is correct. The other options mix up hormones, enzymes, and pigments with incorrect categories.
Answer: Radio isotopes
Tracer elements are substances added in very small amounts to track chemical or biological processes. Radioisotopes are ideal tracers because their radiation can be detected without disturbing the system.
Q7. Glycogen is a/an
Answer: Polymer of glucose.
Glycogen is the main storage polysaccharide in animals, and polysaccharides are long chains of sugar monomers. In glycogen, the repeating monomer is glucose, so it is a polymer of glucose.
Q8. Vitamins are generally involved in forming component of enzyme called
Answer: Coenzyme and prosthetic group
Many vitamins are converted into coenzymes, and some vitamin-derived molecules act as prosthetic groups. Since both are non-protein components involved in enzyme function, the best answer is the one that includes both.
Q9. Characteristic smell of urine is due to
Answer: Urea
Normal urine has a characteristic smell mainly because of urea and its breakdown products. Pus would suggest infection, and uric acid is not the primary cause of the usual urine odor.
Q10. Structure of RNA can be studied by
Answer: x-ray crystallography
X-ray crystallography is used to determine the three-dimensional structure of molecules, including RNA, by analyzing how X-rays diffract through a crystal. The other options are mainly stains or separation methods, not structural determination techniques.
Q11. Which one of the following statements is wrong?
Answer: Hemicellulose
Cellulose, chitin, and peptidoglycan are classic structural polymers. Hemicellulose is a heterogeneous group of plant cell-wall polysaccharides, not a single structural polymer like the others, so it is the wrong statement here.
Q12. Macro molecule chitin is :
Answer: Nitrogen containing polysaccharide
Chitin is a structural polysaccharide made of N-acetylglucosamine units, so it contains nitrogen. That is why it is classified as a nitrogen-containing polysaccharide.
Q13. Which of the following is a reducing sugar?
Answer: galactose
Galactose is a monosaccharide with a free hemiacetal anomeric carbon, so it can open to its aldehyde form and act as a reducing sugar. Gluconic acid is oxidized, β-methyl galactoside is a glycoside with the anomeric carbon blocked, and sucrose is nonreducing because both anomeric carbons are tied up in the glycosidic bond.
Q14. A polysaccharide, which is synthesized and stored in liver cells, is
Answer: glycogen
Glycogen is the main polysaccharide used by animals to store glucose, especially in liver cells. The other options are not storage polysaccharides: lactose is a disaccharide, while galactose and arabinose are monosaccharides.
Q15. In which one of the following groups, all the three are examples of polysaccharides?
Answer: Starch, glycogen, cellulose
Starch, glycogen, and cellulose are all polysaccharides because each is a large polymer made of many glucose units. The other options include mono- or disaccharides such as glucose, fructose, sucrose, maltose, lactose, or galactose.
Answer: Glucose + Galactose
Lactose is the milk sugar, and it is a disaccharide made from glucose and galactose. The enzyme lactase breaks it into these two monosaccharides during digestion.
Q17. For its activity, carboxypeptidase requires
Answer: zinc
Carboxypeptidase is a zinc-dependent metalloenzyme. The zinc ion helps polarize the substrate and activate a water molecule for hydrolysis of peptide bonds.
Q18. In germinating seeds fatty acids are degraded exclusively in the
Answer: glyoxysomes
Glyoxysomes are specialized peroxisomes in germinating seeds that contain enzymes for fatty acid beta-oxidation and the glyoxylate cycle. This lets seedlings convert stored lipids into carbohydrates before photosynthesis begins.
Q19. Uridine, present only in RNA is a
Answer: Nucleoside
Uridine consists of a nitrogenous base (uracil) linked to a sugar (ribose), which makes it a nucleoside. A nucleotide would require one or more phosphate groups, and pyrimidine/purine refer only to the base type.
Answer: Proline is unique in that it is the only amino acid where the side chain is connected to the protein backbone twice.
Proline is special because its side chain cyclizes back onto the backbone nitrogen, making a ring and connecting to the backbone twice. That structural constraint is what makes the correct statement true.