Mix Examples-Biomolecules Questions in English

(D) Aspartic acid is an $\alpha$-amino acid.
Insulin is a peptide hormone.
Ascorbic acid is Vitamin $C$.
Rhamnose is a deoxy sugar,which is a type of carbohydrate.
Therefore,the correct sequence is Aspartic acid,Insulin,Ascorbic acid,Rhamnose.

(A) The components are analyzed as follows:
$a$) Cane sugar (Sucrose) is a disaccharide composed of $\alpha$-$D$-glucose and $\beta$-$D$-fructose.
$b$) Milk sugar (Lactose) is a disaccharide composed of $\beta$-$D$-galactose and $\beta$-$D$-glucose.
$c$) Cellulose is a polysaccharide composed of $\beta$-$D$-glucose units.
$d$) Amylose is a polysaccharide composed of $\alpha$-$D$-glucose units.
Therefore,both cane sugar $(a)$ and amylose $(d)$ contain $\alpha$-$D$-glucose units.

(C) The explanations of the given statements are as follows:
$(A)$ $A$ tripeptide contains $3$ amino acids linked by $2$ peptide bonds. Thus,statement $(A)$ is correct.
$(B)$ $A$ pentapeptide contains $5$ amino acids linked by $4$ peptide bonds. Thus,statement $(B)$ is correct.
$(C)$ $A$ nucleoside is a product of a base and a sugar. $A$ nucleotide is a product of a base,a sugar,and a phosphate group. Thus,statement $(C)$ is incorrect.
$(D)$ In cellulose,$\beta-D$-glucose units are joined by $\beta$-glycosidic linkages between $C-1$ of one glucose and $C-4$ of the next glucose unit. Thus,statement $(D)$ is correct.
Therefore,the correct statements are $(A)$,$(B)$,and $(D)$. Hence,option $(C)$ is correct.

(B) Statement $a$ is correct: Maltose is a disaccharide formed by two $\alpha-D$-glucose units linked by an $\alpha(1 \rightarrow 4)$ glycosidic bond.
Statement $b$ is correct: The quaternary structure describes the spatial arrangement and interaction of multiple polypeptide subunits in a protein.
Statement $c$ is correct: Nucleotides in $DNA$ and $RNA$ are linked by $3'-5'$ phosphodiester bonds.
Statement $d$ is correct: $A$ deficiency in thyroxine hormone production results in hypothyroidism.
Therefore,all statements $a, b, c,$ and $d$ are correct.

(C) nucleoside is composed of a pentose sugar and a nitrogenous base.
$A$ nucleotide is composed of a nucleoside and a phosphate group.
Option $A$ shows a nucleotide (cytidine monophosphate).
Option $B$ shows a sugar phosphate.
Option $C$ shows a nucleoside (uridine),which consists of a nitrogenous base (uracil) attached to a pentose sugar (ribose).
Option $D$ shows a pentose sugar (ribose).

(D) $I)$ According to Chargaff's rule,in $DNA$,the amount of adenine equals thymine $(A = T)$. This is correct.
$II)$ In $RNA$,adenine pairs with uracil,but there is no rule stating their amounts must be equal. This is incorrect.
$III)$ Amylose is a linear polymer of $\alpha-D$-glucose units linked by $\alpha-1 \rightarrow 4$ glycosidic linkages. Amylopectin is the branched polymer. This is incorrect.
$IV)$ Addison disease is caused by the hypofunctioning of the adrenal cortex,leading to a deficiency of glucocorticoids and mineralocorticoids. This is correct.
Therefore,statements $I$ and $IV$ are correct.

(D) Statement $(i)$ is correct: Carbohydrates are stored as glycogen in animals.
Statement $(ii)$ is incorrect: In glycylalanine,the peptide bond is formed between the carboxyl group of glycine and the amino group of alanine. Therefore,the carbonyl group $(C=O)$ of the peptide bond belongs to glycine,not alanine.
Statement $(iii)$ is incorrect: $A$ unit consisting of a nitrogenous base,a sugar,and a phosphate group is known as a nucleotide. $A$ nucleoside consists only of a base and a sugar.
Statement $(iv)$ is correct: Obesity can be a symptom of hypothyroidism due to a slowed metabolic rate.
Thus,statements $(ii)$ and $(iii)$ are incorrect.

(B) $X$ is Sucralose,which is a trichloro derivative of sucrose. It contains a glycosidic linkage between the glucose and fructose units.
$Y$ is Aspartame,which is a dipeptide methyl ester of aspartic acid and phenylalanine. It contains both amide (peptide) and ester linkages.
Therefore,the correct pair is Sucralose and Aspartame.

(D) Sodium benzoate is metabolized in the body to form $Hippuric \ acid$ (or $Hippurate$).
This process involves the conjugation of benzoic acid with glycine,which is then excreted in the urine.

(B) Norethindrone is a steroid derivative.
By examining its structure,we can identify the rings present in the steroid nucleus (gonane skeleton).
It consists of three six-membered rings (labeled $A$,$B$,and $C$) and one five-membered ring (labeled $D$).
Therefore,the number of six-membered rings is $3$ and the number of five-membered rings is $1$.

(C) Dopamine is a neurotransmitter produced in several areas of the brain. $A$ deficiency of dopamine is associated with Parkinson's disease. The $IUPAC$ name of dopamine is $2-(3,4-\text{dihydroxyphenyl})\text{ethylamine}$. Its structure consists of a benzene ring with two hydroxyl groups at the $3$ and $4$ positions and an ethylamine side chain $(-CH_2CH_2NH_2)$ at the $1$ position. This corresponds to the structure shown in option $C$.