Biomolecules

Step 1: Identify the main carbohydrate in milk.
Milk contains lactose (milk sugar), which is a disaccharide.
Step 2: Digestion (hydrolysis) of lactose.
Lactose is broken down by enzyme lactase into:

Step 3: Match with options.
Among options, glucose is a correct digestion product.
Final Answer:

Step 1: Meaning of essential amino acids.
Essential amino acids are those which cannot be synthesized by the human body and must be obtained from diet.
Step 2: Check the given amino acids.
Essential amino acids include:
Leucine, Lysine, Tryptophan, Valine, Isoleucine, Methionine, Threonine, Phenylalanine, Histidine.
Step 3: Analyze options.
(A) Alanine and tyrosine are non-essential incorrect.
(C) Alanine and glutamine are non-essential incorrect.
(D) Proline and glycine are non-essential incorrect.
(B) Leucine, lysine, tryptophan are all essential correct.
Final Answer:

Step 1: Understand ketohexose.
Ketohexose means:
- keto = contains ketone group
- hexose = contains 6 carbon atoms
Step 2: Identify among options.
Glucose is an aldohexose (aldehyde + 6 carbons).
Sucrose is a disaccharide, not a monosaccharide.
Ribose is a pentose (5 carbons).
Fructose is a monosaccharide with 6 carbons and a ketone group, hence ketohexose.
Final Answer:

Step 1: Understand the concept.
A tripeptide consists of 3 amino acids linked in a sequence.
Different sequences give different peptides.
Step 2: Count permutations of 3 different amino acids.
Amino acids: Gly, Ala, Phe (all different).
Number of tripeptides possible:

Step 3: List them (for clarity).

Final Answer:

Step 1: Understand codon definition.
A codon is a sequence of three nucleotide bases in mRNA.
So:

Step 2: What does codon specify?
Each codon codes for a specific amino acid.
So:

Step 3: Where is amino acid incorporated?
Amino acids are incorporated into polypeptide chain which forms protein.
So:

Final Answer:

Step 1: Recall dopamine structure.
Dopamine is 3,4-dihydroxyphenethylamine.
It contains:
- Benzene ring
- Two adjacent groups (catechol)
- side chain
Step 2: Match with given structures.
Option (c) shows:
- Catechol ring ( at 3 and 4 positions)
- substituent
So it matches dopamine exactly.
Final Answer:

Step 1: Role of magnesium in biology.
Magnesium is the central metal ion in the porphyrin-like ring structure of chlorophyll.
Step 2: Compare with haemoglobin.
Haemoglobin contains iron (Fe) as central metal, not Mg.
Step 3: Therefore correct biomolecule.
Chlorophyll is present in plants and is essential for photosynthesis.
Final Answer:

Step 1: Identify reducing acid.
Among carboxylic acids, formic acid is unique because it contains an aldehydic hydrogen.
Step 2: Reason for reducing behaviour.
Formic acid can get oxidized to , hence it reduces Tollens’ reagent and Fehling’s solution.
Step 3: Conclusion.
Thus formic acid shows reducing property.
Final Answer:

Step 1: Define secondary structure.
The secondary structure of a protein involves the local folding patterns such as -helices and -sheets formed by the backbone interactions of the protein's amino acid sequence.
Step 2: Conclusion.
Thus, the secondary structure refers to the -helical backbone and similar structures.
Final Answer:

Vitamin B-complex includes water-soluble vitamins, whereas vitamins A, D, and E are fat-soluble.

Step 2: Conclusion.
Vitamin B-complex is not a fat-soluble vitamin, corresponding to option (a).

Vitamin B-complex includes water-soluble vitamins, while vitamins A, D, E, and K are fat-soluble.

Step 2: Conclusion.
The correct answer is Vitamin B-complex, as it is not fat-soluble, corresponding to option (a).

Denaturation of proteins disrupts their secondary and tertiary structures, but does not affect the primary structure. Denaturation can also involve the conversion of double-stranded DNA into single strands.

Step 2: Conclusion.
The correct statements are (i) and (iii), corresponding to option (c).

Monosaccharides give a positive test with Benedict’s solution, whereas proteins and amino acids react with ninhydrin. The absence of a ninhydrin test indicates it is not a protein or amino acid.

By calculating the mass of nitrogen in a single molecule and using the molar mass of nitrogen, we determine that there are three nitrogen atoms in a caffeine molecule.

Step 1: Identifying the Protein.
Keratin is the structural protein found in hair, skin, and nails. It is a fibrous protein that provides strength and elasticity.
Step 2: Conclusion.
The correct answer is (B), Keratin.

Step 1: Understand the properties of Lactose.
Lactose is a reducing sugar, meaning it can reduce other substances and undergo mutarotation, where its specific rotation changes as the anomeric forms interconvert.
Step 2: Conclusion.
Thus, Lactose does exhibit mutarotation, and statement (3) is incorrect.
Final Answer:

Step 1: Complementary base pairing.
In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Therefore, the complementary strand will have the bases paired accordingly.
Step 2: Conclusion.
The complementary strand for is .
Final Answer:

Step 1: Understand the process of saponification.
Saponification of coconut oil, which is a triglyceride, produces glycerol and fatty acids like palmitic acid. The fatty acid then forms a soap in the presence of sodium hydroxide.
Step 2: Conclusion.
Thus, the product is sodium palmitate.
Final Answer:

Step 1: The given structure indicates a carbohydrate with a ketone group and 6 carbon atoms. Hence, it is a ketohexose.

Final Answer:

The Fischer projection for (2R, 3S)-2,3-butanediol should correctly show the stereochemistry at both the 2nd and 3rd positions as given by the R and S configurations.
Final Answer:

Glucose contains five hydroxyl groups, which can react with methanol in the presence of HCl to form methyl glucosides.
Final Answer:

The heat of formation of CO can be derived from Hess's Law, by adding and subtracting the enthalpy changes of the reactions. The result is .

Step 2: Conclusion.
Thus, the correct answer is .

Markovnikov's rule states that in the addition of HX to an alkene, the hydrogen atom adds to the carbon with the greater number of hydrogen atoms. The exception is the compound , which does not follow this rule.

Step 2: Conclusion.
Thus, the correct answer is .

Step 1: Understanding the Terms
Specific Conductance ( ): Given as .
Molar Conductance ( ): This is the conductance of all ions produced by 1 mole of the electrolyte in a solution.
Step 2: Formula for Molar Conductance
The molar conductance ( ) is calculated using the formula: where:
is the specific conductance,
is the concentration of the solution in mol/L (0.1 M in this case).
Step 3: Substituting the Values
Substitute the given values into the formula:
Step 4: Matching with the Options
The calculated molar conductance is , which corresponds to option (C). Final Answer: The molar conductance of the solution is (C) .

In the lanthanide series, the ionic size of lanthanoids decreases as we move from to because the effective nuclear charge increases with the increasing atomic number while the electron shielding remains nearly constant. Lanthanum and Lutetium have the smallest ionic radii in the oxidation state. Lutetium ( ) has the smallest ionic radius because of the f
block contraction, where the size of the atoms decreases as the atomic number increases from to . Final Answer: Option (d) .