Biomolecules · JEE Advanced previous year questions

A linear octasaccharide ($\text{molar mass}=1024{\text{ g mol}}^{-1}$) on complete hydrolysis produces three monosaccharides: ribose, 2-deoxyribose and glucose. The amount of 2-deoxyribose formed is $58.26\%$ (w/w) of the total amount of the monosaccharides produced in the hydrolyzed products. The number of ribose unit(s) present in one molecule of octasaccharide is _________. $\text{Use:}$ Molar mass (in ${\text{g mol}}^{-1}$): ribose $=150$, 2-deoxyribose $=134$, glucose $=180$; Atomic mass (in $\text{amu}$): $\mathrm{H}=1$, $\mathrm{O}=16$

1. A.(A)
2. B.(B)
3. C.(C)
4. D.(D)

For a double strand DNA, one strand is given below: $$5^{\prime }\text{A G T C A C G T A A G T C}{3}^{\prime }$$ The amount of energy required to split the double strand DNA into two single strands is ____ $\mathrm{kcal}\mathrm{mo}{\mathrm{l}}^{-1}$. [Given: Average energy per H-bond for A-T base pair = $1.0\mathrm{kcal}\mathrm{mo}{\mathrm{l}}^{-1}$, G-C base pair = $1.5\mathrm{kcal}\mathrm{mo}{\mathrm{l}}^{-1}$, and A-U base pair = $1.25\mathrm{kcal}\mathrm{mo}{\mathrm{l}}^{-1}$. Ignore electrostatic repulsion between the phosphate groups.]

In the scheme given below, $\mathbf{X}$ and $\mathbf{Y}$, respectively, are $$\text{Metal halide}\stackrel{aq.\mathrm{NaOH}}{\to }\text{White precipitate }(\mathbf{P})+\text{Filtrate }(\mathbf{Q})$$ $$\mathbf{P}\underset{\mathrm{heat}}{\overset{\begin{array}{c}aq.{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4,\\ \mathrm{Pb}{\mathrm{O}}_2(\mathrm{excess})\end{array}}{\to }}\mathbf{X}\text{(a coloured species in solution)}$$ $$\mathbf{Q}\underset{\mathrm{warm}}{\overset{\begin{array}{c}\mathrm{MnO}(\mathrm{OH}{)}_2,\\ Conc.{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4\end{array}}{\to }}\mathbf{Y}\text{(gives blue-coloration with KI-starch paper)}$$

1. A.$\mathrm{Cr}{\mathrm{O}}_4^{2-}$ and $\mathrm{B}{\mathrm{r}}_2$
2. B.$\mathrm{Mn}{\mathrm{O}}_4^{2-}$ and $\mathrm{C}{\mathrm{l}}_2$
3. C.$\mathrm{Mn}{\mathrm{O}}_4^{-}$ and $\mathrm{C}{\mathrm{l}}_2$
4. D.$\mathrm{MnS}{\mathrm{O}}_4$ and $\mathrm{HOCl}$