Biomolecules

To determine which compound is being described, we need to analyze the given chemical tests and their results:

1. Negative test with ninhydrin: Ninhydrin is a chemical reagent commonly used to detect amino acids and proteins. When it reacts with these compounds, it typically produces a deep purple color known as Ruhemann's purple. Therefore, a negative test with ninhydrin implies that the compound does not contain free amino groups, ruling out amino acids (Option A) and proteins (Option D).

2. Positive test with Benedict's solution: Benedict's solution is used to test for the presence of reducing sugars. If the compound is a reducing sugar, it will reduce the copper(II) ions in Benedict's solution to form a brick-red precipitate of copper(I) oxide when heated. Therefore, a positive test with Benedict's solution indicates the presence of a reducing sugar.

Given these observations, the compound must be a reducing sugar. Thus, the correct answer is:

Option B: a monosaccharide.

Let's analyze the given statements:

Assertion A: "Amylose is insoluble in water." This statement is incorrect. Amylose is actually soluble in water, although its solubility is lower compared to other carbohydrates like amylopectin.

Reason R: "Amylose is a long linear molecule with more than 200 glucose units." This statement is correct, as amylose is indeed a linear polysaccharide made up of glucose units.

Given this information, the correct option is:

Option D: $\mathbf{A}$ is not correct but $\mathbf{R}$ is correct.

The sugar gives +ve Tollen’s test hence it’s a reducing sugar.

Hence in sucrose glycosidic linkage between $\mathrm{C}_{1}$ of $\alpha$-glucose and $C_{2}$ of $\beta$-D-fructose is found

Maltose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$

Lactose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$

Amylose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$

The primary structure of protein is unaffected by physical 'or' chemical changes.

Both (A) and (R) are true but (R) is not correct explanation for (A), as the amino acids exist in dipolar form due to presence of positive $\left(-\stackrel{+}{\mathrm{N}} \mathrm{H}_3\right)$ group and negative ( $-\mathrm{COO}^{-}$) group. The dipolar form is called as Zwitter ion form.

Fructose possess molecular formula $\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6$. Structure of $D$ and $L$ fructose are

$D$ and $L$ configurations are relative configurations. Glucose and fructose

both have -OH group on the bottom carbon to the right side. They have same $D$-configuration. Hence, they are called $D$-glucose and $D$-fructose. So, assertion (A) is true. Glucose rotates plane polarised light to the right side or clockwise direction. So, it is dextrorotatory.

Whereas fructose rotates plane polarised light to left side or anti-clockwise. So, fructose is laevorotatory. So, given reason (R) is false.

1 mole of sucrose on acid hydrolysis produces 1 mole of glucose and 1 mole of fructose.

$ \underset{\text { Sucrose }}{\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}} \xrightarrow{\text { Acid hydrolysis }} \underset{\text { Glucose }}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6}+\underset{\text { Fructose }}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6} $

Molecular mass of sucrose

$ \begin{aligned} & =(12 \times \text { atomic mass of } \mathrm{C})+(22 \times \text { mass of } \\ & \mathrm{H})+(11 \times \text { Atomic mass of } \mathrm{O}) \\ & =(12 \times 12)+(22 \times 1)+(11 \times 16)=342 \mathrm{~g} \end{aligned} $

Therefore, amount of sucrose needed to produce 1 mole of glucose using acid hydrolysis is 342 g .

The structure of proteins is destroyed by the application of heat or chemical agents and the process i. called denaturation. It involves the disruption of both the secondary and tertiary structures of a protein, but the primary structure, which involves a sequence of amino acids does not get disturbed and remains intact. This results in the loss of the biological activity of the proteins.

The protein in milk is normally suspended in a colloidal solution, which means that the small protein molecules float around freely and independently. On adding lime juice to milk the pH decreases and the small protein molecules gets coagulated and forms large chain. This is denaturing of protein and causes curdling.

Therefore the (A) is false but (R) is true.

$\text { Sucrose } \xrightarrow{\text { Invertase }} \text { Glucose }+ \text { Fructose }$

$\begin{aligned} & \text { Proteins } \xrightarrow{\text { Pepsin }} \text { Peptides } \\ & \text { Starch } \xrightarrow{\text { Diastase }} \text { Maltose } \end{aligned}$

$\text { The correct match is A-II, B-III, C-IV. }$

Carbohydrates are stored in plants and animals in different forms because their storage needs and structures vary. In plants, carbohydrates are typically stored as starch, while in animals, they are stored as glycogen.

To understand this better, let's look at each storage form:

Starch: Starch is a polysaccharide that serves as a storage form of energy in plants. It is composed of two molecules, amylose and amylopectin, which are both polymers of glucose. Starch is stored in plastids (like chloroplasts and amyloplasts) within plant cells.

Glycogen: Glycogen is a highly branched polysaccharide formed of glucose units, similar to starch but more extensively branched. It is the primary storage form of carbohydrate in animals and is predominantly stored in the liver and muscle tissues.

Given these details, the correct forms of carbohydrate storage in plants and animals are:

Option D: Starch in plants and Glycogen in animals.

Glycylalanine is a dipeptide made up of glycine and L-alanine residues. When glycine and alanine link together, a water molecule is released and glycylalanine is formed which works as a metabolite:

Our body needs vitamin $\mathrm{B}_{12}$ to make red blood cells. Deficiency of vitamin $\mathrm{B}_{12}$ causes a rare blood disorder also known as pernicious anemia. It is characterised by inability of body to produce red blood cells.

Vitamin C is a water soluble vitamin. So, it is excreted with the urine. Other vitamins like, A, E and K are fat soluble thus, can be stored in the body.

But vitamin C cannot be stored in the body.

Glucagon is a peptide hormone produced by alpha cells of pancreas. It raises the concentration of blood glucose in human.

A peptide bond is formed when carboxyl group of $\alpha$-amino acid reacts with amine group of $\alpha$-amino acids. This proceeds by dehydration i.e. removal of a water molecule.

Hence, three molecules of phenyl hydrazine (C₆H₅NHNH₂) is used to yield osazone.

Fibrous proteins are characterized by their elongated, insoluble structure and often serve structural or mechanical roles. Among the options provided, keratin, collagen, and myosin are examples of fibrous proteins.

Albumin, on the other hand, is a globular protein that is soluble in water. It has a more spherical shape compared to the elongated shape of fibrous proteins. Albumin is found in blood plasma and has various functions including maintaining osmotic pressure.

So, the correct answer is:

Option B: Albumin.

Given structure of compound A is thymine, so its complementary base will be adenine.

Adenine form hydrogen bonds with thymine and cytosine will form hydrogen bond with guanine.