Cellulose is the most abundant organic compound on Earth. It is the main constituent of plant fiber; plants contain on average 33% cellulose, and cotton is the purest form at 90%. Cellulose is a linear polymer of as many as 10,000 D-glucose units. Answer : (c)

Alanine is a non-essential amino acid made in the body from either the conversion of the carbohydrate pyruvate or the breakdown of DNA and the dipeptides carnosine and anserine Answer : (d)

Chitin, which occurs in nature as ordered macrofibrils, is the major structural component in the exoskeletons of the crustaceans, crabs and shrimps, as well as the cell walls of fungi. Answer : (c)

The basic repeating unit of nucleic acids are known as nucleotides. Answer : (d)

The water-soluble vitamins include ascorbic acid (vitamin C), thiamin, riboflavin, niacin, vitamin B6 (pyridoxine, pyridoxal, and pyridoxamine), folacin, vitamin B12, biotin, and pantothenic acid. Answer : (b)

The enzyme-substrate complex lower activation energy by bending substrate molecules in a way that facilitates bond-breaking, helping to reach the transition state. Answer : (a)

Feedback inhibition is a cellular control mechanism in which an enzyme's activity is inhibited by the enzyme's end product. This mechanism allows cells to regulate how much of an enzyme’s end product is produced. Answer : (c)

Enzyme activity can be affected by a variety of factors, such as temperature, pH, and concentration. Enzymes work best within specific temperature and pH ranges, and sub-optimal conditions can cause an enzyme to lose its ability to bind to a substrate Answer : (c)

Isomerases are a general class of enzymes that convert a molecule from one isomer to another. Isomerases facilitate intramolecular rearrangements in which bonds are broken and formed. i.e. changes in structure Ligases are enzymes that are capable of catalyzing the reaction of joining two large molecules by establishing a new chemical bond. Hydrolases are enzymes that catalyze the cleavage of a covalent bond using water. Types of hydrolase include esterases, such as phosphatases, that act on ester bonds, and proteases or peptidases that act on amide bonds in peptides. Transferases are enzymes that catalyze the transfer of a group of atoms, such as amine, carboxyl, carbonyl, methyl, acyl, glycosyl, and phosphoryl from a donor substrate to an acceptor compound. Answer : (b)

The specific action of an enzyme with a single substrate can be explained using a Lock and Key analogy first postulated in 1894 by Emil Fischer. Answer : (b)

An apoenzyme is an inactive enzyme, activation of the enzyme occurs upon binding of an organic or inorganic cofactor. Coenzymes are organic nonprotein molecules that bind with the protein molecule (apoenzyme) to form the active enzyme (holoenzyme). The combination of the apoenzyme and the coenzyme results in the formation of a functional enzyme which is called holoenzyme. Answer : (b)

Formula: C18H34O2 Answer : (c)

The middle lamella is a layer which cements the cell walls of two adjoining plant cells together. The middle lamella is made up of calcium and magnesium pectates. Answer : (a)

agar is a polymer of galactose Answer : (a)

ELISA: Enzyme-linked immunosorbent assay ELISA is a rapid immunochemical test that involves an enzyme used for measuring a wide variety of tests of body fluids. ELISA tests detect substances that have antigenic properties, primarily proteins rather than small molecules and ions, such as glucose and potassium Answer : (c)

Positive supercoiling is the right-handed, coiling of DNA thus winding occurs in the clockwise direction. Answer : (b)

The active coenzyme form of thiamin, vitamin B1, is thiamin pyrophosphate (TPP) Biotin is a coenzyme for multiple carboxylase enzymes. The active forms of riboflavin, vitamin B2, are the coenzymes flavin mononucleotide Answer : (a)

Holoenzyme a biochemically active compound formed by the combination of an enzyme with a coenzyme. Answer : (c)

Sterols, also known as steroid alcohols, are a subgroup of the steroids and an important class of organic molecules. They are a type of lipid. The most familiar type of animal sterol is cholesterol, which is vital to cell membrane structure, and functions as a precursor to fat-soluble vitamins and steroid hormones Answer : (c)

In the DNA helix, the bases: adenine, cytosine, thymine and guanine are each linked with their complementary base by hydrogen bonding. Adenine pairs with thymine with 2 hydrogen bonds. Guanine pairs with cytosine with 3 hydrogen bonds. Answer : (a)

Heparin is an anticoagulant (blood thinner) that prevents the formation of blood clots. Heparin does not break down clots that have already formed (unlike tissue plasminogen activator) but allows fibrinolysis to work normally to break down clots. Heparin is used to treat and prevent blood clots in the veins, arteries, or lung. Heparin is also used before surgery to reduce the risk of blood clots. Answer : (c)

Riboflavin (Vitamin B2) is the precursor of two coenzymes known as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Answer : (d)

The structure of protein insulin was first studied by Sanger. It consists of two polypeptide chains which are linked by the disulphide bonds. Answer : (a)

The immediate source of energy for most cells is glucose. But glucose is not the only fuel on which cells depend. Answer : (b)

Cofactor: The first type of enzyme partner is a group called cofactors, or molecules that increase the rate of reaction or are required for enzyme function. Coenzymes A specific type of cofactor, coenzymes, are organic molecules that bind to enzymes and help them function. The key here is that they're organic. Prosthetic Groups: Prosthetic groups are cofactors that bind tightly to proteins or enzymes. As if holding on for dear life, they are not easily removed. Answer : (c)

Glycogen is a polysaccharide that is the principal storage form of glucose (Glc) in animal and human cells. Glycogen is a sparsely soluble (and therefore osmotically inactive) branched polyssacharide, composed of glucose monomers joined through glycosidic bonds. Answer : (d)

In the synthesis of protein, three types of RNA are required. ribosomal RNA (rRNA), transfer RNA (tRNA) and messenger RNA (mRNA) Answer : (d)

Glycogen stores in skeletal muscle serve as a form of energy storage for the muscle itself; however, the breakdown of muscle glycogen impedes muscle glucose uptake from the blood, thereby increasing the amount of blood glucose available for use in other tissues. Answer : (b)

The three main omega-3 fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) Saturated Fatty Acids examples: Lauric acid, myristic acid, palmitic acid, Stearic acid, Arachidic acid Unsaturated Fatty Acids examples: Palmitoleic acid, Oleic acid, Linoleic acid, myristoleic acid, Answer : (d)

Component	% of the total cellular mass
Water	70-90
Proteins	10-15
Lipids	2
Carbohydrates;	3
Mucleic acids	5-7
Ions	1

Average Composition of Cells Principal organic constituent of a living being in order of relative abundance is Proteins Answer : (b)

Inulin is a heterogeneous collection of fructose polymers Answer : (c)

Amino acids are organic compounds containing an amino group and an acidic group as substituents on the same carbon i.e., the α-carbon. Most amino acids are synthesized from α-ketoacids, and later transaminated from another amino acid, usually glutamate. A "transamination reaction", in which an amino group is transferred from an amino acid to the a-carbon of a ketoacid, is catalyzed by an aminotransferase Answer : (d)

Starch Storage product, a- r Haemoglobin Transport of gases, b - s RNA Protein synthesis, c - p Steroid Sex hormon, d - q Answer : (b)

Human blood contains a buffer of carbonic acid (H2CO3) and bicarbonate anion (HCO3-) in order to maintain blood pH between 7.35 and 7.45 Answer : (c)

Nucleic acids contain the same elements as proteins: carbon, hydrogen, oxygen, nitrogen; plus phosphorous (C, H, O, N, and P) Answer : (d)

Cellulose xanthate is a compound produced from cellulose in the viscose process for making rayon. Answer : (a)

Magnesium is the element located-in centre of porphyrin ring of chlorophyll Answer : (c)

Plant cell walls are primarily made of strong fibers of the carbohydrate polymer cellulose Answer : (a)

Each enzyme (E) has a substrate (S) binding site in its molecule so that a highly reactive enzyme-substrate complex (ES) is produced. Km is a measure of the affinity an enzyme has for its substrate, as a lower Km means that less of the substrate is required to reach half of Vmax. Answer : (b)

The stored starch is used by the tubers during unfavourable condition like dormancy. Starch is formed by a-1,4 linkages between two glucose unit which is broken down during its digestion. It is storage food material of plant cells. Answer : (a)

The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine Answer : (b)

Holoenzyme is produced by a biochemically active compound formed by the combination of an enzyme with a coenzyme. Answer : (a)

Lipids also encompass molecules such as fatty acids. Linoleic acid is classified as an essential nutrient, since the body requires it but cannot synthesize it. Other essential fatty acids are eicosapentaenoic acid, gamma-linolenic acid, dihomo-gamma-linolenic acid or arachidonic acid or AA Answer : (b)

Benedict's reagent can also be used to test for the presence of glucose in urine, elevated levels of which is known as glucosuria. Substance in water + 3 mL Benedict's solution → then boil for few minutes and allow to cool. → Red, green, or yellow precipitate is obtained Reducing sugar, such as glucose, is present Substance in water + 3 mL Benedict's solution → then boil for few minutes and allow to cool → Solution remains clear or is a little blue Reducing sugar is not present Answer : (b)

They contain hydrogen and oxygen in the same ratio as water (2:1) Sucrose formula: C12H22O11 Maltase is a enzyme that catalyzes the hydrolysis of the disaccharide maltose to the simple sugar glucose Glycerol formula: C3H8O3 Answer : (c)

Glucose formula: C6H12O6 Answer : (b)

A fat molecule is mono-unsaturated if it contains one double bond, and poly-unsaturated if it contains more than one double bond. Answer : (c)

Malonate is a competitive inhibitor of the enzyme succinate dehydrogenase: malonate binds to the active site of the enzyme without reacting, and so competes with succinate, the usual substrate of the enzyme. Malonate resembles the substrate succinate, without a −CH2CH2− group required for dehydrogenation Answer : (a)

Calmodulin (CaM) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. Answer : (c)

Three biologically active double helical structures are A-DNA, B-DNA and Z-DNA. Answer : (a)