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#	Question	Answer
1	What is observed when elemental analysis is performed on living tissues?	Elements like carbon, hydrogen, oxygen and several others are found in living tissues.
2	What are the two fractions obtained after straining tissue slurry?	Acid-soluble pool (filtrate) and acid-insoluble fraction (retentate).
3	What is found in the acid-soluble pool?	Thousands of organic compounds.
4	What are biomolecules?	All carbon compounds obtained from living tissues are called biomolecules.
5	What is meant by wet weight?	The weight of a small amount of living tissue before drying.
6	What remains after a tissue is fully burnt?	Ash containing inorganic elements and compounds.
7	Name some inorganic elements present in ash.	Calcium and magnesium.
8	Which inorganic compounds are found in the acid-soluble fraction?	Sulphates and phosphates.
9	What does elemental analysis reveal?	The elemental composition of living tissues such as hydrogen, oxygen, chlorine and carbon.
10	What does compound analysis reveal?	The kind of organic and inorganic constituents present in living tissues.
11	What are amino acids?	Organic compounds containing an amino group and an acidic group attached to the same carbon (alpha-carbon).
12	Why are amino acids called alpha-amino acids?	Because both amino and acidic groups are attached to the same alpha-carbon.
13	Amino acids are substituted forms of which compound?	Methane.
14	What are the four substituent groups attached to the alpha-carbon of amino acids?	Hydrogen group, carboxyl group, amino group and variable R group.
15	Which amino acid has hydrogen as its R group?	Glycine.
16	Which amino acid has a methyl group as its R group?	Alanine.
17	Which amino acid contains a hydroxymethyl group as its R group?	Serine.
18	Which amino acid is an example of an acidic amino acid?	Glutamic acid.
19	Which amino acid is an example of a basic amino acid?	Lysine.
20	Which amino acid is an example of a neutral amino acid?	Valine.
21	Name the aromatic amino acids mentioned in the text.	Tyrosine, phenylalanine and tryptophan.
22	On what do the chemical and physical properties of amino acids depend?	The amino group, carboxyl group and R functional group.
23	How are amino acids classified based on the number of amino and carboxyl groups?	Acidic, basic and neutral amino acids.
24	Which amino acids are examples of aromatic amino acids?	Tyrosine, phenylalanine and tryptophan.
25	What is the zwitterionic form of an amino acid?	The ionic form formed in solutions of different pH due to ionization of amino and carboxyl groups.
26	Are lipids generally water soluble or insoluble?	Lipids are generally water insoluble.
27	What are simple lipids commonly made of?	Simple fatty acids or glycerol (trihydroxy propane).
28	What is the structure of a fatty acid?	A carboxyl group attached to an R group.
29	How many carbons are present in palmitic acid?	16 carbons including the carboxyl carbon.
30	How many carbons are present in arachidonic acid?	20 carbons including the carboxyl carbon.
31	What are saturated fatty acids?	Fatty acids without double bonds.
32	What are unsaturated fatty acids?	Fatty acids with one or more C=C double bonds.
33	What is glycerol chemically known as?	Trihydroxy propane.
34	How are fatty acids associated with glycerol in many lipids?	Fatty acids are esterified with glycerol.
35	What are monoglycerides, diglycerides and triglycerides?	Lipids formed when fatty acids are esterified with glycerol.
36	On what basis are fats and oils differentiated?	Melting point.
37	Why do oils remain liquid in winters?	Because they have lower melting points.
38	What are phospholipids?	Lipids containing phosphorus and a phosphorylated organic compound.
39	Where are phospholipids commonly found?	In the cell membrane.
40	Give one example of a phospholipid.	Lecithin.
41	Which tissues contain lipids with more complex structures?	Neural tissues.
42	Name all the nitrogen bases mentioned in the text.	Adenine, guanine, cytosine, uracil and thymine.
43	What are nucleosides?	Nitrogen bases attached to a sugar.
44	What are nucleotides?	Nucleosides with a phosphate group esterified to the sugar.
45	Name all the nucleosides mentioned in the text.	Adenosine, guanosine, thymidine, uridine and cytidine.
46	Name all the nucleotides mentioned in the text.	Adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid.
47	What are nucleic acids made of?	Nucleotides only.
48	Which nucleic acids function as genetic material?	DNA and RNA.
49	What are metabolites?	Biomolecules present in living organisms are called metabolites.
50	What are primary metabolites?	Biomolecules commonly found in animal tissues such as amino acids and sugars are called primary metabolites.
51	In which organisms are secondary metabolites commonly found?	Plant, fungal and microbial cells.
52	Give examples of secondary metabolites.	Alkaloids, flavonoids, rubber, essential oils, antibiotics, coloured pigments, scents, gums and spices.
53	What is the major difference between primary and secondary metabolites?	Primary metabolites have identifiable functions in physiological processes, whereas functions of many secondary metabolites are not fully understood.
54	Name some secondary metabolites useful to human welfare.	Rubber, drugs, spices, scents and pigments.
55	What is the molecular weight range of compounds in the acid-soluble pool?	Approximately 18 to 800 daltons (Da).
56	Which four classes of organic compounds are present in the acid-insoluble fraction?	Proteins, nucleic acids, polysaccharides and lipids.
57	What are biomacromolecules?	Compounds found in the acid-insoluble fraction (except lipids) with molecular weights in the range of ten thousand daltons and above.
58	What are micromolecules?	Biomolecules with molecular weights less than one thousand daltons.
59	Why are lipids included in the acid-insoluble fraction despite low molecular weight?	Because they occur as membrane structures forming insoluble vesicles after tissue grinding.
60	Are lipids true macromolecules?	No, lipids are not strictly macromolecules.
61	What does the acid-soluble pool roughly represent?	Cytoplasmic composition.
62	What does the acid-insoluble fraction represent?	Macromolecules from cytoplasm and organelles.
63	What is the most abundant chemical in living organisms?	Water.
64	What percentage of cellular mass is water ?	70 - 90%.
65	What percentage of cellular mass is made up of proteins?	10 - 15%.
66	What percentage of cellular mass is carbohydrates?	3%.
67	What percentage of cellular mass is lipids?	2%.
68	What percentage of cellular mass is nucleic acids?	5 - 7%.
69	What percentage of cellular mass is ions?	1%.
70	What are proteins chemically?	Proteins are polypeptides.
71	How are amino acids linked in proteins?	By peptide bonds.
72	Why are proteins called heteropolymers?	Because they are made of different types of amino acids.
73	How many types of amino acids occur in proteins?	20 types.
74	What is a homopolymer?	A polymer containing only one type of repeating monomer.
75	What are essential amino acids?	Amino acids that must be supplied through diet.
76	Which protein is the most abundant in the animal world?	Collagen.
77	Which is the most abundant protein in the biosphere?	Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO).
78	Which macromolecule is another major component of the acid-insoluble pellet?	Polysaccharides (carbohydrates).
79	What are polysaccharides?	Long chains of sugars made of monosaccharides as building blocks.
80	What is cellulose?	A polymeric polysaccharide made only of glucose units.
81	Why is cellulose called a homopolymer?	Because it consists of only one type of monosaccharide, glucose.
82	What is the function of starch in plants?	It acts as a storehouse of energy in plant tissues.
83	What is glycogen?	A polysaccharide variant found in animals for storage.
84	Which polysaccharide is a polymer of fructose?	Inulin.
85	In a polysaccharide chain, which end is called the reducing end?	The right end.
86	In a polysaccharide chain, which end is called the non-reducing end?	The left end.
87	Which polysaccharide forms helical secondary structures?	Starch.
88	What are plant cell walls mainly made of?	Cellulose.
89	Paper and cotton fibres are mainly composed of which substance?	Cellulose.
90	Name some chemically modified sugars mentioned in the text.	Glucosamine and N-acetyl galactosamine.
91	What is chitin?	A complex polysaccharide present in the exoskeleton of arthropods.
92	What are nucleic acids chemically classified as?	Polynucleotides.
93	Which macromolecules together form the true macromolecular fraction of living tissue?	Polynucleotides, polysaccharides and polypeptides.
94	What are the three components of a nucleotide?	A heterocyclic compound, a monosaccharide and phosphoric acid/phosphate.
95	Which nitrogenous bases are purines?	Adenine and guanine.
96	Which nitrogenous bases are pyrimidines?	Cytosine, uracil and thymine.
97	What is DNA?	A nucleic acid containing deoxyribose sugar.
98	What is RNA?	A nucleic acid containing ribose sugar.
99	What are proteins described as in structure?	Heteropolymers containing strings of amino acids.
100	What is the primary structure of a protein?	The sequence and positional information of amino acids in a protein.
101	Which amino acid is called the N-terminal amino acid?	The first amino acid in a protein chain.
102	Which amino acid is called the C-terminal amino acid?	The last amino acid in a protein chain.
103	Which type of helices are observed in proteins?	Right-handed helices.
104	What is the secondary structure of proteins?	Folding of portions of the protein thread into helices and other forms.
105	What is the tertiary structure of proteins?	Folding of the long protein chain upon itself into a three-dimensional structure.
106	Why is tertiary structure important in proteins?	It is absolutely necessary for many biological activities of proteins.
107	What is quaternary structure of proteins?	The arrangement of individual folded polypeptide subunits with respect to each other.
108	How many subunits are present in adult human haemoglobin?	Four subunits.
109	What types of subunits are present in adult human haemoglobin?	Two alpha-type and two Beta-type subunits.
110	What are ribozymes?	Nucleic acids that behave like enzymes.
111	What is the primary structure of an enzyme?	The amino acid sequence of the protein.
112	What is the active site of an enzyme?	A crevice or pocket into which the substrate fits.
113	How do enzymes catalyse reactions?	Through their active sites.
114	How do enzyme catalysts differ from inorganic catalysts?	Enzymes get damaged at high temperatures, whereas inorganic catalysts work efficiently at high temperatures and pressures.
115	Which organisms possess heat-stable enzymes?	Thermophilic organisms living in hot vents and sulphur springs.
116	What is a physical change?	A change in shape or state without breaking chemical bonds.
117	Give examples of physical processes mentioned in the text.	Melting of ice into water and conversion of water into vapour.
118	What is a chemical reaction?	A process in which bonds are broken and new bonds are formed.
119	Which organic reaction is mentioned as an example?	Hydrolysis of starch into glucose.
120	What does the rate of a chemical or physical process indicate?	Amount of product formed per unit time.
121	How do catalysed reactions compare with uncatalysed reactions?	Catalysed reactions proceed at much higher rates.
122	Which enzyme accelerates the formation of carbonic acid in the cytoplasm?	Carbonic anhydrase.
123	By approximately how many times does carbonic anhydrase accelerate the reaction?	About 10 million times.
124	What is a metabolic pathway?	A multistep chemical reaction where each step is catalysed by the same enzyme complex or different enzymes.
125	Into what is glucose converted in the metabolic pathway mentioned?	Pyruvic acid.
126	How many enzyme-catalysed reactions convert glucose into pyruvic acid?	Ten different reactions.
127	What is formed in skeletal muscles under anaerobic conditions?	Lactic acid.
128	What is formed under normal aerobic conditions?	Pyruvic acid.
129	What is produced in yeast during fermentation?	Ethanol (alcohol).
130	What is the substrate in an enzyme reaction?	The chemical that is converted into a product.
131	Where does the substrate bind on the enzyme?	At the active site within a cleft or pocket.
132	What is formed when substrate binds to the enzyme?	Enzyme-substrate (ES) complex.
133	What is the transition state structure?	The new structure formed when the substrate is bound to the enzyme active site.
134	What happens after bond breaking and bond making are completed?	The product is released from the active site.
135	What does the y-axis represent in the activation energy graph?	Potential energy content.
136	What does the x-axis represent in the activation energy graph?	Progression of structural transformation through the transition state.
137	What is an exothermic reaction according to the graph explanation?	A reaction where product energy level is lower than substrate energy level.
138	What is activation energy?	The difference in average energy content of substrate and transition state.
139	How do enzymes help in reactions?	They lower the activation energy barrier.
140	What is necessary for catalysis by enzymes?	Formation of the enzyme-substrate (ES) complex.
141	What happens after the ES complex forms?	It dissociates into product(s) and unchanged enzyme through enzyme-product (EP) complex.
142	What is the first step in the catalytic cycle of enzyme action?	Substrate binds to the active site of the enzyme.
143	What happens to the enzyme shape after substrate binding?	The enzyme alters its shape to fit more tightly around the substrate.
144	What happens at the active site during catalysis?	Chemical bonds of the substrate are broken and enzyme-product complex forms.
145	What happens after product release from the enzyme?	The free enzyme is ready to bind another substrate molecule.
146	Which factors can alter the tertiary structure of enzymes?	Temperature, pH, substrate concentration and binding of specific chemicals.
147	Enzymes generally function within what range of temperature and pH?	A narrow range of temperature and pH.
148	What is optimum temperature?	The temperature at which an enzyme shows highest activity.
149	What is optimum pH?	The pH at which an enzyme shows highest activity.
150	What happens to enzyme activity above and below optimum temperature or pH?	Enzyme activity declines.
151	What effect does low temperature have on enzymes?	It preserves enzymes in a temporarily inactive state.
152	Why does high temperature destroy enzyme activity?	Because proteins are denatured by heat.
153	What happens to reaction velocity with increase in substrate concentration?	Reaction velocity initially rises.
154	What is Vmax in enzyme kinetics?	The maximum reaction velocity reached by an enzyme-catalysed reaction.
155	Why does reaction velocity stop increasing after Vmax?	Because all enzyme molecules become saturated with substrate.
156	What is inhibition?	The process in which binding of a chemical shuts off enzyme activity.
157	What is an inhibitor?	A chemical that binds to an enzyme and reduces its activity.
158	What is a competitive inhibitor?	An inhibitor that resembles the substrate structurally and competes for the substrate-binding site.
159	How does a competitive inhibitor reduce enzyme activity?	By competing with the substrate for the active site, preventing substrate binding.
160	Which enzyme is inhibited by malonate?	Succinic dehydrogenase.
161	Which substrate does malonate resemble structurally?	Succinate.
162	Competitive inhibitors are often used in the control of what?	Bacterial pathogens.
163	Into how many major classes are enzymes divided?	Six classes.
164	What are oxidoreductases/dehydrogenases?	Enzymes catalysing oxidation-reduction reactions between substrates.
165	What are transferases?	Enzymes catalysing transfer of groups other than hydrogen between substrates.
166	What are hydrolases?	Enzymes catalysing hydrolysis of ester, ether, peptide and other bonds.
167	What are lyases?	Enzymes that remove groups from substrates without hydrolysis, leaving double bonds.
168	What are isomerases?	Enzymes catalysing interconversion of optical, geometric or positional isomers.
169	What are ligases?	Enzymes catalysing the linking together of two compounds.
170	What are cofactors?	Non-protein constituents bound to enzymes to make them catalytically active.
171	What is an apoenzyme?	The protein portion of an enzyme.
172	Name the three kinds of cofactors.	Prosthetic groups, co-enzymes and metal ions.
173	What are prosthetic groups?	Organic compounds tightly bound to the apoenzyme.
174	Which prosthetic group is present in peroxidase and catalase?	Haem (which is part of the active site).
175	What reaction is catalysed by peroxidase and catalase?	Breakdown of hydrogen peroxide into water and oxygen.
176	What are co-enzymes?	Organic compounds loosely associated with apoenzymes during catalysis.
177	How are co-enzymes different from prosthetic groups?	Co-enzymes are transiently associated, while prosthetic groups are tightly bound to apoenzymes.
178	What are the essential chemical components of many co-enzymes?	Vitamins.
179	Which vitamin is present in NAD and NADP?	Niacin.
180	Why are metal ions important for some enzymes?	They are required for enzyme activity.
181	Which metal ion acts as a cofactor for carboxypeptidase?	Zinc.
182	What happens when cofactors are removed from enzymes?	Catalytic activity is lost.
183	Which chemical is the most abundant in living organisms?	Water.
184	What is the molecular weight range of small biomolecules?	Less than 1000 daltons (Da).
185	Name some small biomolecules mentioned in the summary.	Amino acids, monosaccharides, disaccharides, fatty acids, glycerol, nucleotides and nucleosides.
186	How many types of amino acids are present in living organisms?	20 types.
187	How many types of nucleotides are present in living organisms?	5 types.
188	What are fats and oils chemically called?	Glycerides (monoglycerides, diglycerides, and triglycerides) in which fatty acids are esterified to glycerol.
189	What additional component is present in phospholipids?	A phosphorylated nitrogenous compound.
190	Which three true macromolecules are found in living systems?	Proteins, nucleic acids and polysaccharides.
191	Why are lipids found in the macromolecular fraction?	Due to their association with membranes.
192	What are biomacromolecules made of?	Different building blocks forming polymers.
193	What are proteins made of?	Amino acids.
194	What are nucleic acids composed of?	Nucleotides.
195	What are the four hierarchical structures of biomacromolecules?	Primary, secondary, tertiary and quaternary structures.
196	What is the function of nucleic acids?	They serve as genetic material.
197	What is the role of polysaccharides in plants and fungi?	They form components of the cell wall.
198	Which polysaccharides serve as storage forms of energy?	Starch and glycogen.
199	Name some functions of proteins mentioned in the summary.	Enzymes, antibodies, receptors, hormones and structural proteins.
200	Which protein is the most abundant in the animal world?	Collagen.
201	Which protein is the most abundant in the biosphere?	Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO).
202	What are ribozymes?	Nucleic acids with catalytic power.
203	What conditions are required for maximal enzyme activity?	Optimum temperature and optimum pH.
204	What happens to enzymes at high temperatures?	They become denatured.
205	How do enzymes affect activation energy?	They lower activation energy and increase reaction rate.
206	What is the function of nucleic acids in heredity?	They carry hereditary information from parents to progeny.