261.
The given structures (I) and (II) represent configuration of the simplest sugar glyceraldehyde. Which of the following statements is not correct for the structures?
\[\underset{\left( \text{I} \right)}{\mathop{\underset{\begin{smallmatrix}
|\,\,\,\, \\
\,\,\,\,\,\,C{{H}_{2}}OH
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,CHO \\
|\,\,\,\,
\end{smallmatrix}}{\mathop{H-C-OH}}}\,}}\,\,\,\,\,\,\,\underset{\left( \text{II} \right)}{\mathop{\underset{\begin{smallmatrix}
\,\,\,\,| \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{{H}_{2}}OH
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,\,\,\,\,\,\,\,CHO \\
\,\,\,\,|
\end{smallmatrix}}{\mathop{HO-C-H}}}\,}}\,\]
A
(I) represents $$D$$ - form while (II) represents $$L$$ - form of glyceraldehyde.
B
The sugars having same configuration as $$D$$ - glyceraldehyde are designated as $$D$$ - sugars.
C
Natural glucose and fructose are $$D$$ - forms.
D
$$D$$ is dextrorotatory while $$L$$ is laevorotatory enantiomer.
Answer :
$$D$$ is dextrorotatory while $$L$$ is laevorotatory enantiomer.
262. Primary structure of a protein is
A
sequence in which $$\alpha $$ - amino acids are linked to one another
B
sequence in which amino acids of one polypeptide chain are joined to other chain
C
the folding patterns of polypeptide chains
D
the pattern in which the polypeptide chains are arranged
Answer :
sequence in which $$\alpha $$ - amino acids are linked to one another
263. $$\alpha - D - \left( + \right) - $$ glucose and $$\beta - D - \left( + \right) - $$ glucose are
A
conformers
B
epimers
C
anomers
D
enatiomers
Answer :
anomers
264. The secondary structure of a protein refers to
A
fixed configuration of the polypeptide backbone
B
$$\alpha - $$ helical backbone
C
hydrophobic interactions
D
sequence of $$\alpha - $$ amino acids.
Answer :
$$\alpha - $$ helical backbone
265. Which one of the following is not correct?
A
$$D\left( - \right)$$ Fructose exists in furanose structure.
B
$$D\left( + \right)$$ Glucose exists in pyranose structure.
C
In sucrose the two monosaccharides are held together by peptide linkage.
D
Maltose is a reducing sugar.
Answer :
In sucrose the two monosaccharides are held together by peptide linkage.
266. The predominant form of histamine present in human blood is $$\left( {p{K_a},\,{\text{Histidine}} - 6.0} \right)$$
A
B
C
D
Answer :
267. Glucose on prolonged heating with $$HI$$ gives :
A
$$n\, - $$ Hexane
B
1 - Hexene
C
Hexanoic acid
D
6 - iodohexanal
Answer :
$$n\, - $$ Hexane
268.
Compounds $$I$$ and $$II$$ may be grouped as
A
diastereomers
B
epimers
C
$$C–2$$ epimers
D
all of the three.
Answer :
all of the three.
269. Bases common to $$RNA$$ and $$DNA$$ are
A
adenine, guanine, cytosine
B
adenine, uracil, cytosine
C
adenine, guanine, thymine
D
guanine, uracil, thymine
Answer :
adenine, guanine, cytosine
270.
During the process of digestion, the proteins present in food materials are hydrolysed to amino acids. The two enzymes involved in the process
\[\text{Proteins}\xrightarrow{\text{Enzyme}\left( \text{A} \right)}\text{Polypeptides}\] \[\xrightarrow{\text{Enzyme}\left( \text{B} \right)}\text{Amino acids,}\] are respectively
A
amylase and maltase
B
diastase and lipase
C
pepsin and trypsin
D
invertase and zymase
Answer :
pepsin and trypsin
