Which of the following statements regarding the chemical analysis of living tissues and elemental comparison are correct?
I. When living tissue is ground in trichloroacetic acid (Cl3CCOOH) and strained through cheesecloth, two fractions are obtained: filtrate (acid-soluble pool) and retentate (acid-insoluble fraction). II. The acid-soluble pool contains organic compounds with molecular weights ranging from 18 to around 800 Daltons. III. The acid-insoluble fraction contains only biomacromolecules with molecular weights strictly above 10,000 Daltons, with no exceptions. IV. Inorganic elements like calcium and magnesium, as well as compounds like sulphate and phosphate, are present in the acid-soluble fraction.
Which of the above statements are correct?
Statement III is incorrect because lipids have molecular weights not exceeding 800 Daltons, yet they separate into the acid-insoluble fraction because cell membranes disrupt into water-insoluble vesicles during grinding. Statements I, II, and IV accurately describe tissue fractionation and the acid-soluble pool.
Question 2 of 100
📘 CLASS XI
Which of the following statements regarding elemental composition and ash analysis of living tissues are correct?
I. All elements present in a sample of Earth's crust are also present in a sample of living tissue. II. The relative abundance of carbon and hydrogen with respect to other elements is higher in living organisms than in Earth's crust. III. When living tissue is fully burnt, water evaporates and all carbon compounds are oxidised to gaseous forms (CO2 and water vapour), leaving behind ash. IV. Silicon is present in a high percentage (27.7%) in the human body compared to Earth's crust.
Which of the above statements are correct?
Statement IV is incorrect because silicon constitutes about 27.7% of the Earth's crust, whereas its amount in the human body is negligible. Statements I, II, and III correctly describe elemental abundance and ash analysis.
Question 3 of 100
📘 CLASS XI
Which of the following statements regarding the structure and classification of amino acids are correct?
I. Amino acids are substituted methanes containing four substituent groups on the α-carbon: hydrogen, carboxyl group, amino group, and a variable R group. II. Proteinaceous amino acids consist of 20 types, where glycine has hydrogen as the R group and alanine has a hydroxy methyl group. III. Glutamic acid is an acidic amino acid, lysine is a basic amino acid, and valine is a neutral amino acid. IV. In solutions of different pH, the structure of amino acids changes due to the ionizable nature of -NH2 and -COOH groups.
Which of the above statements are correct?
Statement II is incorrect because alanine has a methyl (-CH3) group as its side chain, whereas serine has a hydroxymethyl (-CH2OH) group. Statements I, III, and IV are correct.
Question 4 of 100
📘 CLASS XI
Which of the following statements regarding fatty acids, glycerides, and cell membrane lipids are correct?
I. Palmitic acid has 16 carbon atoms including the carboxyl carbon, while arachidonic acid has 20 carbon atoms including the carboxyl carbon. II. Glycerol is chemically trihydroxy propane, and when fatty acids are esterified with glycerol, they form monoglycerides, diglycerides, and triglycerides. III. Lipids are true macromolecules with molecular weights exceeding 10,000 Daltons. IV. Cell membranes disrupted during grinding form water-insoluble vesicles that separate in the retentate fraction.
Which of the above statements are correct?
Statement III is incorrect because lipids are not true macromolecules and generally have molecular weights below 800 Daltons. Statements I, II, and IV are correct.
Question 5 of 100
📘 CLASS XI
Which of the following statements regarding secondary metabolites and their categories are correct?
I. Primary metabolites have identifiable functions and known roles in normal physiological processes, whereas secondary metabolites are produced in plant, fungal, and microbial cells. II. Morphine and codeine are alkaloids, whereas monoterpenes and diterpenes are terpenoids. III. Concanavalin A is a toxin, while abrin and ricin are lectins. IV. Vinblastin and curcumin are secondary metabolites categorized as drugs, whereas rubber, gums, and cellulose are polymeric substances.
Which of the above statements are correct?
Statement III is incorrect because Concanavalin A is a lectin, whereas abrin and ricin are toxins. Statements I, II, and IV correctly describe secondary metabolites.
Question 6 of 100
📘 CLASS XI
Which of the following statements regarding the average chemical composition of living cells are correct?
I. Water is the most abundant chemical in living organisms, comprising 70–90% of total cellular mass. II. Proteins constitute 10–15% of total cellular mass, making them the most abundant organic macromolecule in cells. III. Lipids make up 5–7% of total cellular mass, whereas nucleic acids constitute only 2%. IV. Ions constitute approximately 1% of total cellular mass.
Which of the above statements are correct?
Statement III is incorrect because nucleic acids constitute about 5–7% of total cellular mass, whereas lipids contribute about 2%. Statements I, II, and IV match the NCERT composition table.
Question 7 of 100
📘 CLASS XI
Which of the following statements regarding the structural hierarchy of proteins are correct?
I. Proteins are heteropolymers of amino acids linked by peptide bonds, containing no repeating single monomer units. II. Primary structure of a protein refers to the linear sequence of amino acids, where the N-terminal amino acid is on the right end and the C-terminal is on the left end. III. In proteins, only right-handed helices are observed in secondary structure. IV. Tertiary structure gives a 3-dimensional view of a protein folded upon itself like a hollow woolen ball and is necessary for biological activity.
Which of the above statements are correct?
Statement II is incorrect because the first amino acid (N-terminal) is represented on the left end, while the last amino acid (C-terminal) is on the right end. Statements I, III, and IV correctly summarize protein structural organization.
Question 8 of 100
📘 CLASS XI
Which of the following statements regarding the functions and abundance of specific proteins are correct?
I. Collagen is the most abundant protein in the animal world, serving as intercellular ground substance. II. RuBisCO is the most abundant protein in the whole biosphere. III. GLUT-4 is an antibody that fights infectious agents in the human body. IV. Receptors are protein molecules involved in sensory reception (smell, taste, hormone reception).
Which of the above statements are correct?
Statement III is incorrect because GLUT-4 is a glucose transporter, whereas antibodies fight infectious agents. Statements I, II, and IV correctly identify proteins and their functions.
Question 9 of 100
📘 CLASS XI
Which of the following statements regarding polysaccharide structures and the iodine test are correct?
I. Cellulose is a homopolymer consisting of glucose monosaccharide units. II. Starch forms helical secondary structures that can hold iodine molecules (I2) in the helical portion, yielding a blue colour. III. Cellulose contains complex helices and therefore turns dark blue when reacted with iodine. IV. Glycogen is a branched polysaccharide in animals where the right end is reducing and the left end is non-reducing.
Which of the above statements are correct?
Statement III is incorrect because cellulose does not possess helical structure and therefore does not retain iodine to produce a blue colour. Statements I, II, and IV are correct.
Question 10 of 100
📘 CLASS XI
Which of the following statements regarding complex polysaccharides, inulin, and cell walls are correct?
I. Inulin is a polymeric polysaccharide composed of fructose monomers. II. Plant cell walls are made of cellulose, and paper made from plant pulp as well as cotton fibers are cellulosic. III. Exoskeletons of arthropods contain chitin, which is a complex polysaccharide made of amino-sugars like glucosamine and N-acetyl galactosamine. IV. All complex polysaccharides in nature are heteropolymers with random monosaccharide arrangements.
Which of the above statements are correct?
Statement IV is incorrect because complex polysaccharides such as chitin are predominantly homopolymers rather than heteropolymers. Statements I, II, and III are correct.
