AIIMS Chemistry Biomolecules Class 12 Questions

Assertion: Two sugar units joined by 1,2-glycosidic bond in sucralose. Reason: It contains 1 C-glucose and 2 C -fructose glycosidic bond

In glucose, there is absence of free aldehyde group and it forms cyclic hemiacetal form as shown below.

Starch is a polysaccharide and on reaction with iodine it will give a blue-black color.

Select the correct set of answer:

In the primary structure of proteins, the amino acids are interconnected by-

Amylopectin is

In cyclic structure of glucose, the penta-acetate of glucose does not react with hydroxylamine indicating the absence of free–CHO group.

Glucose on reacting with benedict solution may give the following precipitates except

Which of the following linkage is found in sucrose?

In DNA, deoxy-ribose sugar is present not the D⁻ribose sugar. Therefore, the statement (4) is incorrect.

Guanine is a nucleobase which is mainly found in DNA and RNA. It contains five nitrogen and has two rings. It is a purine base. The structure of guanine is shown below:

Proteins are made up of α-aminoacids. During this formation, NH₂ group of one amino acid condenses with COOH of the other with elimination of a water molecule to form a peptide bond.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choice. Assertion (A) Glucose gives reddish brown precipitate with Fehling solution. Reason (R) Reaction of glucose with Fehling solution gives CuO and gluconic acid.

Assertion (A) A solution of sucrose in water is dextrorotatory while on hydrolysis in presence of little hydrochloric acid, it becomes laevorotatory. Reason (R) Sucrose on hydrolysis gives unequal amounts of glucose and fructose as a result of which change in sign of rotation is observed.

Which of the following is a non-reducing sugar?

Assertion: All enzymes are made up of proteins and all proteins have three dimensional structures. Reason: Secondary structures of protein are sequence of amino acids.

Find the hydrolysis product when a phosphodiester bond of nucleotide breaks.

Find the hydrolysis product of maltose.

Assertion : β-pleated sheet structure of protein shows maximum extension.

The element which is the most abundant in the earth crust is

Assertion : Alpha (α)⁻amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity. Reason : H⁺ ion given by carboxylic group (–COOH) is captured by amino group (–NH₂) having lone pair of electrons.

The pair in which both species have iron is

Among the following L⁻serine is

Thymine is

Lysine is least soluble in water in the pH range

Methyl-α-D⁻glucoside and methyl-β-D⁻glucoside are

Which one of the following biomolecules is insoluble in water?

Which one of the following statements is true for protein synthesis (translation)?

Assertion : Maltose is a reducing sugar which gives two moles of D⁻glucose on hydrolysis. Reason : Maltose has a 1,⁴⁻β-glycosidic linkage.

The nucleic acid base having two possible binding sites is

Melting points are normally the highest for

Assertion : Sucrose is a non-reducing sugar. Reason : It has glycosidic linkage.

Subunits present in haemoglobin are

Among the following, the achiral amino acid is

Assertion : Haemoglobin is an oxygen carrier. Reason : Oxygen binds as O₂⁻ to Fe of haemoglobin.

Assertion : Glycosides are hydrolysed in acidic conditions. Reason : Glycosides are acetals.

Assertion : Activity of an enzyme is pH dependent. Reason : Change in pH affects the solubility of the enzyme in water.

Enzymes with two sites are called

Assertion : DNA molecules and RNA molecules are found in the nucleus of a cell. Reason : On heating, the enzymes do not lose their specific activity.