Biomolecules

Step 1: Definition
Lipids are a broad group of naturally occurring organic molecules.
Step 2: Classification
They include fats, waxes, sterols, and fat-soluble vitamins.
Step 3: Conclusion
In biological terms, naturally occurring fats are primarily classified as lipids.
Final Answer: (D)

Step 1: Understanding the Concept:
This question is about enzyme classification and their functions, specifically those involved in ATP-dependent bond formation.

Step 2: Detailed Explanation:
• (A) Isomerases: Catalyze the rearrangement of atoms within a molecule (isomerization). • (B) Lyases: Catalyze the addition or removal of groups to form double bonds, often without ATP. • (C) Transferases: Catalyze the transfer of a functional group from one molecule to another. • (D) Ligases: Catalyze the joining of two molecules, often with the concomitant hydrolysis of a pyrophosphate bond in ATP (or another nucleoside triphosphate). They are involved in DNA replication (DNA ligase) and other biosynthetic reactions.

Step 3: Final Answer:
Ligases break the pyrophosphate bond of ATP to join two molecules, which corresponds to option (D).

Step 1: Understanding the Concept:
Glucose is an aldohexose. Reduction of the aldehyde group yields a sugar alcohol.
Step 2: Detailed Explanation:
Glucose ( ) has an aldehyde group. Reduction with NaBH reduces the aldehyde to a primary alcohol, forming the corresponding sugar alcohol. The product is D-glucitol, commonly known as sorbitol. Mannitol is obtained from the reduction of mannose, not glucose.
Step 3: Final Answer:
Reduction of glucose gives sorbitol, option (A).

Step 1: Understanding the Concept:
Sweetness is a sensory property of sugars. Different sugars have different relative sweetness compared to sucrose.
Step 2: Detailed Explanation:
The relative sweetness scale (sucrose = 1): \begin{itemize} \item Fructose: 1.7 (sweetest natural sugar) \item Sucrose: 1.0 \item Glucose: 0.7 \item Lactose: 0.2 \end{itemize}
Step 3: Final Answer:
Fructose is the sweetest sugar, option (B).

Step 1: Understanding the Concept:
Proteins are polymers of amino acids. The amino acids that make up proteins are specifically -amino acids.
Step 2: Detailed Explanation:}}
In -amino acids, the amino group ( NH ) and the carboxyl group ( COOH) are attached to the same carbon atom (the -carbon). These are the building blocks of proteins. - and -amino acids are not found in proteins; they have the amino group on the or carbon.
Step 3: Final Answer:
The essential building units of proteins are -amino acids, option (A).

Step 1: Understanding the Concept:
Strecker synthesis is a method for preparing amino acids from aldehydes.
Step 2: Detailed Explanation:
In Strecker synthesis, an aldehyde (formaldehyde, HCHO) is treated with ammonia (NH ) and hydrogen cyanide (HCN) to form an -aminonitrile, which is then hydrolyzed to give the -amino acid (glycine).
Step 3: Final Answer:
Glycine can be obtained from formaldehyde by Strecker synthesis, option (A).

Step 1: Understanding the Concept:
Starch is a polysaccharide.
Step 2: Detailed Explanation:
Starch is a polymer of -D-glucose units.
Step 3: Final Answer:
Starch is a polymer of glucose.

Step 1: Understanding the Concept:
Insulin is a polypeptide hormone.
Step 2: Detailed Explanation:
Human insulin consists of 51 amino acids (21 in A-chain and 30 in B-chain).
Step 3: Final Answer:
Insulin has 51 amino acids.

Step 1: Understanding the Concept:
Molisch test is a general test for carbohydrates.
Step 2: Detailed Explanation:
Molisch test is a general test for all carbohydrates.
Step 3: Final Answer:
Molisch test is given by all carbohydrates.

Step 1: Understanding the Concept:
Aspirin is acetyl salicylic acid.
Step 2: Detailed Explanation:
Aspirin is used as analgesic (pain reliever) and antipyretic (fever reducer).
Step 3: Final Answer:
Analgesic drug.