Biomolecules · JEE Main previous year questions

Which one of the following bases is not present in DNA?

1. A.Cytosine
2. B.Thymine
3. C.Quinoline
4. D.Adenine

The difference between the reaction enthalpy change (${\Delta }_{r}H$) and reaction internal energy change (${\Delta }_{r}U$) for the reaction: $2{\mathrm{C}}_6{\mathrm{H}}_6(\mathrm{l})+15{\mathrm{O}}_2(\mathrm{g})⟶12C{\mathrm{O}}_2(\mathrm{g})+6{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$ at $300\mathrm{K}$ is ($R=8.314\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$)

1. A.$0\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}$
2. B.$2490\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}$
3. C.$-2490\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}$
4. D.$-7482\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}$

All of the following statements apply to proteins except

1. A.Proteins generally have no definite melting point
2. B.Proteins contain the grouping $-\mathrm{CONH}-$
3. C.Proteins have high molecular weight
4. D.Proteins can only contain the elements C, H, O and N.

The two functional groups present in a typical carbohydrate are

1. A.-OH and -COOH
2. B.-CHO and -COOH
3. C.> C = O and - OH
4. D.- OH and -CHO

$18\mathrm{g}$ of glucose (${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$) is added to $178.2\mathrm{g}$ of water. The vapour pressure of water for this aqueous solution at $100^{\circ }\mathrm{C}$ is

1. A.$759.00\mathrm{Torr}$
2. B.$7.60\mathrm{Torr}$
3. C.$76.00\mathrm{Torr}$
4. D.$752.40\mathrm{Torr}$

The term anomers of glucose refers to

1. A.isomers of glucose that differ in configurations at carbons one and four (C-1 and C-4)
2. B.a mixture of (D)-glucose and (L)-glucose
3. C.enantiomers of glucose
4. D.isomers of glucose that differ in configuration at carbon one (C-1)

The pyrimidine bases present in DNA are

1. A.cytosine and adenine
2. B.cytosine and guanine
3. C.cytosine and thymine
4. D.cytosine and uracil

Consider the reaction: ${\mathrm{N}}_2+3{\mathrm{H}}_2\to 2N{\mathrm{H}}_3$ carried out at constant temperature and pressure. If $\Delta H$ and $\Delta U$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?

1. A.$\Delta H>\Delta U$
2. B.$\Delta H<\Delta U$
3. C.$\Delta H=\Delta U$
4. D.$\Delta H=0$

In both DNA and RNA, heterocyclic base and phosphate ester linkages are at-

1. A.$C_5^{\prime }$ and $C_2^{\prime }$ respectively of the sugar molecule
2. B.$C_2^{\prime }$ and $C_5^{\prime }$ respectively of the sugar molecule
3. C.$C_1^{\prime }$ and $C_5^{\prime }$ respectively of the sugar molecule
4. D.$C_5^{\prime }$ and $C_1^{\prime }$ respectively of the sugar molecule

Identify the correct statements regarding enzymes

1. A.Enzymes are specific biological catalysts that can normally function at very high temperature (T ~ 1000 K)
2. B.Enzymes are specific biological catalysts that the posses well – defined active sites
3. C.Enzymes are specific biological catalysts that can not be poisoned
4. D.Enzymes are normally heterogeneous catalysts that are very specific in their action

Which base is present in RNA but not in DNA?

1. A.Uracil
2. B.Thymine
3. C.Guanine
4. D.Cytosine

The functional group, which is found in amino acid is

1. A.-COOH group
2. B.-$\mathrm{N}{\mathrm{H}}_2$ group
3. C.-$\mathrm{C}{\mathrm{H}}_3$ group
4. D.both (a) and (b)

RNA is different from DNA because RNA contains

1. A.ribose sugar and thymine
2. B.ribose sugar and uracil
3. C.deoxyribose sugar and thymine
4. D.deoxyribose sugar and uracil