Biomolecules - 1 - JEE MCQ

RNA nucleotides contain ribose sugars while DNA contains deoxyribose and RNA uses predominantly uracil instead of thymine present in DNA.

The correct answer is Option B
A hormone is a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour. Insulin is a hormone which is responsible for the level of sugar in blood and hence maintaining the level of diabetes.

In both DNA and RNA, the heterocyclic base is attached to the C1' carbon of the sugar molecule, and the phosphate ester linkage occurs at the C5' carbon. The phosphate group is covalently bonded to the C5' of one sugar and the C3' of the adjacent sugar in the nucleotide chain.

Water-soluble vitamins dissolve in water and are not stored by the body. The water soluble vitamins include the vitamin B-complex group and vitamin C.

(c): DNA contains two types of nitrogeneous bases

• Purine → Adenine (A) and guanine (G)
• Pyrimidine → Cytosine (C) and thymine (T)

The purine and pyrimidine bases pair only in certain combination. Adenine pairs with thymine (A: T) by two hydrogen bonds and guanine with cytosine
(G: C) by three hydrogen bonds.

RNA has D (-) - Ribose and the DNA has 2-Deoxy D (-) - ribose as the carbohydrate unit.

From the structures it is clear that 2^nd carbon in DNA do not have OH group.

The two isomeric forms (a - and b -) of D-glucopyronose differ in configuration only at C-1,
hence these are called anomers.

(b): Enzymes are proteins that act as catalyst for bio-chemical processes of life. They speed up these reactions enormously and with a high degree of selectivity.

Hence, the correct answer is Option A.

Adenine and Guanine are substituted purines while the rest ( Thymine, cytosine, uracil) are substituted pyrimidines.

Option C: Human body can synthesise all proteins they need.
This statement is not true because the human body cannot synthesize all the amino acids required to build proteins. There are certain amino acids known as essential amino acids that must be obtained through the diet because the body cannot synthesize them. Examples include valine, leucine, and lysine.

Thus, total number of stereoisomers in pyranose form of D-configuration = 2³ = 8.

Ring (A) is a six-membered pyranose ring, and the glycosidic bond formed at carbon-1 of Ring (A) is in the α-configuration (directed downwards). Therefore, the correct statement is: Option A

Chlorophyll is an organometallic complex in which the central atom is 'Mg' just like 'Fe' in haemoglobin. It's formula is found to be C₅₅H₇₂M_gN₂O₆, which is the green colouring matter of leaves and green stems.

Nitrogeneous bases are liked together by hydrogen bonds.

The correct answer is Option B - hydrogen bonds.
α-helix structure is formed when the chain of α-amino acids coil as a right handed screw because of the formation of hydrogen bonds between amide groups of the same peptide chain, i.e NH group in one unit is linked to carbonyl oxygen of the third unit by hydrogen bonding. This H-bonding is responsible for holding helix in a position.

Since α - D - (+) - glucose and β - D - (+) - glucose differ in configuration at C-1 atom so they are anomers.
NOTE: Anomers are those diastereomers that differ in configuration at C-1 atom.
i.e., (c) in the correct answer.

These isomers differ only in the orientation (or configuration) at C₁ atom.

Cyclization of the open chain structure of D-(+)-glucose has created a new stereocenter at C₁ which explains the existence of two cyclic forms of D-(+)-glucose, namely α- and β-. These two cyclic forms are diastereomers, such diastereomers which differ only in the configuration of chiral carbon developed on hemiacetal formation (it is C₁ in glucose and C₂ in fructose) are called anomers and the hemiacetal carbon (C₁ or C₂) is called the anomeric carbon.

These dissolve in fats and are stored in the body's fatty tissues and liver. They do not need to be consumed as frequently as water-soluble vitamins.

1. Vitamin A (Retinol, Beta-Carotene)
2. Vitamin D (Cholecalciferol)
3. Vitamin E (Tocopherol)
4. Vitamin K (Phylloquinone, Menaquinone)