Biology · Chemistry

Biomolecules and Enzymes

1,501 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Carbonic anhydrase is the best known example of 

  1. Hydrolase

  2. Transferase

  3. Lyase

  4. Coagulative
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lyase are the enzymes which catalyze breakdown reactions without hydrolysis. Lyases are classified as EC 4 in the EC number classification of enzymes. Lyases can be further classified into several subclasses : EC 4.1 includes lyases that cleave carbon-carbon bonds, such as decarboxylases (EC 4.1.1), aldehyde lyases (EC 4.1.2), oxo acid lyases (EC 4.1.3) and others (EC 4.1.99).

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The fastest acting enzyme, in the biological kingdom, is 

  1. Lipase

  2. Amylase

  3. Peptidase

  4. Carbonic anhydrase
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are biological catalysts which catalyze biological reactions. They do not modify the chemical equilibria in any manner but simply make the attainment of equilibrium faster. Carbonic anhydrase catalyzes reversible reaction between carbon dioxide and water to form carbonic acid. This enzyme is one of the fastest enzyme. It is especially abundant in human erythrocytes.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

First discovered enzyme was

  1. Isomerase

  2. Transaminase

  3. Zymase

  4. Transferase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these

  1. Are exclusively synthesized in the body of a living organism as at present.

  2. Enhance oxidative metabolism.

  3. Are conjugated proteins.

  4. Help in regulating metabolism.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
There are more than thousand of biomolecules involve in living organisms in various biological processes. Some are vitamins, hormones, enzymes, ATP, carbohydrates, lipids, nucleic acids and proteins. Out of these main carbohydrates, proteins, lipids and nucleic acid are main biomolecules which play a vital role in living systems and mainly responsible for almost all biochemical processes. The biological molecules or biomolecules are involved in metabolic activities of living bodies such as plants and animals. Most of the biomolecules in the living cell have some broad functions like:
1. They are essential to cellular and body structure.
2. They act as energy-rich fuels during cellular respiration.
3. The molecules are used to carry information of controlling growth and biological characteristics from one generation to another.
4. They are good catalytic agents for the various chemical processes occur in cell and living body.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which one of the following hydrolyze internal phosphodiester bonds in a polynucleotide chain?

  1. Lipase

  2. Protease

  3. Exonuclease

  4. Endonuclease
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Endonucleases hydrolyse internal phosphodiester bonds in a polynucleotide chain. Function of nucleases is to break phosphodiester bond. A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Nucleases are usually further divided into endonucleases and exonucleases, although some of the enzymes may fall in both categories. 

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which enzyme act as chromosomal breaks?

  1. DNA polymerase

  2. DNase

  3. DNA ligase

  4. DNA polymerase II
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The enzyme that cause chromosomal breaks are DNase. A deoxyribonuclease or DNase, is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. Deoxyribonucleases are one type of nuclease, a generic term for enzymes capable of hydrolising phosphodiester bonds that link nucleotides.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which of the following set of three items are true, as each set belongs to the category mentioned against them?

  1. Lysine, glycine, thiamine - Amino acids

  2. Myosin, oxytocin and gastrin - Hormones

  3. Rennin, helicase and hyaluronidase - Enzyme

  4. Optic nerve, oculomotor, vagus - Sensory nerves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rennin is a protease found in rennet. It is produced by newborn ruminant animals in the lining of the fourth stomach to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese.

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
Hyaluronidase is a protein enzyme. It works by causing rapid spreading of injected fluid into the body, which increases the absorption of injected fluids.
Therefore, the correct answer is option C.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which enzyme shows greatest substrate specificity?

  1. Nuclease

  2. Trypsin

  3. Sucrase

  4. Pepsin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Enzymes are highly specific catalysts and show high degree of substrate specificity. Some enzymes names are general and these enzymes act on a type of biomolecules. For example: nucleases means enzymes acting on nucleic acids. Nuclease is a general class of enzyme. Similarly, pepsin and trypsin are protein metabolising enzymes. These enzymes will act on any proteins and not on some specific protein. Sucrase is, however, a specific enzyme which will act on sucrose only.
So, the correct answer 'Sucrase'
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Non-proteinaceous enzyme that acts as a catalyst for the formation of peptide bond is
OR
"All enzymes are proteins." This statement is now modified because an apparent exception to this biological truth is

  1. Spliceosome

  2. Ribozyme

  3. RNA polymerase I

  4. RNA polymerase III
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ribozymes or RNA enzymes are catalytic RNA molecules. The first ribozyme discovered was self splicing group I intron. The second catalytic RNA was RNAase P which separates tRNA from hn RNA at their 5' ends. Peptidyl transferase involved in translation of proteins is also catalytic RNA. Telomerase is a ribonulceoprotein  enzyme. It is involved in replication of terminal DNA or telomeres.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Molecular scissors which cut DNA at specific site is known as

  1. Pectinase

  2. Polymerase

  3. Restriction endonuclease

  4. Ligase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A restriction enzyme or restriction endonuclease or molecular scissors is an enzyme used in genetic engineering that splices DNA at or near specific recognition nucleotide sequences, known as restriction sites. Thus, the correct answer is option C.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which of the following enzyme is not of protein origin?

  1. Hexokinase

  2. Synthetase

  3. Endonuclease

  4. Ribozyme
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are biological catalysts which catalyse the biochemical reactions in living systems. Majority of enzymes are proteins. A small minority of enzymes are catalytic RNA molecules. These catalytic RNA molecules are called ribozymes. These catalytic RNA molecules catalyze reactions like splicing of introns during processing of RNA in eukaryotic mRNA.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which of the following enzymes has/have heme as a prosthetic group?
(i) Catalase                            

(ii) Carboxypeptidase
(iii) Succinic dehydrogenase 

(iv) Peroxidase

  1. (i) Only

  2. (i) and (ii)

  3. (ii) and (iii)

  4. (iii) and (iv)

  5. (i) and (iv)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Co-enzymes tightly or covalently bonded to enzymes are called prosthetic groups, e.g., pyridoxal phosphate, heme, biotin. Heme is a prosthetic group containing ferrous ion. It is important for a number of biologically important hemoproteins such as myoglobin, cytochrome oxidase, catalase and peroxidase. Thus, the correct answer is option E.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

In which one of the following enzymes, is copper necessarily associated as an activator?

  1. Lactic dehydrogenase

  2. Tyrosinase

  3. Carbonic anhydrase

  4. Trytophanase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Some enzymes require metal ions for their activity. Tyrosinase is a copper containing enzyme that catalyzes the production of melanin and other pigments.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

A simple enzyme is 

  1. Succinate dehydrogenase

  2. Urease

  3. Transaminase

  4. Ribozyme
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Simple enzymes consist of only proteins and catalyze their substrate specific reactions. Urease is an enzyme which is only made up of protein and it functions to catalyze the hydrolysis of urea which results in the formation of ammonia and carbon dioxide.

Succinate dehydrogenase is an enzyme complex consisting of four polypeptides (SDH A-D) which catalyses the conversion of succinate to fumarate during cellular respiration.
Transaminase signifies a group of enzymes which catalyze transamination reaction.
Ribozymes are also called catalytic RNAs. These are RNA enzymes catalyzing peptide bonding reaction during protein synthesis.
Thus, the correct answer is 'Urease is a simple enzyme'.