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 properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Which of the following is the transition state structure of the substrate formed during an enzymatic reaction?

  1. Permanent but unstable

  2. Transient and unstable

  3. Permanent and stable

  4. Transient but stable
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reactions do not undergo chemical changes automatically. They do so in transition states. Transition state has more free energy than reactants or products. Higher free energy helps in collision of transition state reactants. The enzymes binds to substrate molecules and form an unstable transient state called as transition state. The transition state rapidly undergoes degeneration into products and unchanged enzyme molecule.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

What is true for an enzyme during a biochemical reaction?

  1. It becomes part of the product

  2. It is unchanged

  3. It is broken down into amino acids

  4. It reacts with fatty acids

  5. It becomes a polypeptide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Any chemical reaction includes the formation of transition state between reactant and product. The energy required for formation of the transition state is termed as activation energy. Enzymes enhance the rate of reaction by lowering down the activation energy of transition state but themselves remain unchanged. Thus, the correct answer is option B.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Which of the following is iron porphyrin coenzyme or cofactor?

  1. Cytochrome

  2. FAD

  3. CoA

  4. NAD
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hemes are the iron containing porphyrins. They are extensively found in nature. These are also present in proteins like haemoglobin and myoglobin. Cytochromes are also a haemoproteins. Cytochrome also act as an integral part of membrane protein.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Enzymes which transfer electrons are

  1. Hydrolyses

  2. Hydrogenases

  3. Proteases

  4. Transaminases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Enzymes which helps in the transfer of electrons are known as hydrogenases. It catalyzes the reversible oxidation of hydrogen to protons by the loss of electrons. The electron acceptors like oxygen are reduced in this particular reaction while electron donors like ferredoxin are oxidized.
Hydrolyses are the enzyme which catalyzes the splitting of compounds by addition of water.
Proteases hydrolyze the peptide bond.
Transaminase catalyzes aminotransferase reaction between an amino acid and a α-keto acid.
So, the correct answer is option B.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology
Holoenzyme is the complete enzyme consisting of an apoenzyme and a co-factor. Select the option that correctly identifies the nature of apoenzyme and co-factor.

  1. Apoenzyme - Protein
    Co - factor - Non-Protein

  2. Apoenzyme - Non - Protein
    Co - factor - Protein

  3. Apoenzyme - Protein
    Co - factor - Protein

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conjugated enzymes ( holoenzymes) are formed of two parts a protein part called apoenzyme and a non-protein part named co-factor. The complete conjugated enzyme consisting of an apoenzyme and a co-factor is called holoenzyme. Holoenzyme is the functional unit of enzyme. 

${\underset{(active\,\, enzyme)}{Holoenzyme}}$ $\rightarrow$  ${\underset {(protein\,\, part)}{Apoenzyme}}$ $+ co-factor$
Co-factor may be inorganic or organic in nature. Catalystic activity is lost when co-factor is removed from the enzyme which indicates that it plays a crucial role in catalytic activity of enzymes.
So, the correct answer is 'Apoenzyme - Protein, Co - factor - Non-Protein'.

Multiple choice zoology aids to health immunity and the lines of immunity immune system of the body immunity and blood groups

Which one forms chemical barrier for infections?

  1. Isozyme

  2. Coughing

  3. Lysozyme

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

Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase is an antibacterial enzyme produced by animals and humans that forms part of the innate immune system. Lysozyme is abundant in secretions including tears, saliva, human milk, sweat and mucus. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils. Lysozyme is an enzyme and hence, acts as a chemical barrier of infection.

So, the correct answer is 'Lysozyme'.

Multiple choice biology tissues muscle tissue structure of protein muscle tissues

Which one is both structural and functional (catalytic) protein?

  1. Hexokinase

  2. Myosin

  3. Ribozyme

  4. Acetyl Co-A
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Myosin is found in muscle filaments. The head portion of myosin forms cross linkage with actin filaments during muscular contraction. The cross bridges between actin and myosin are very important for muscular contraction activity. Thus, myosin fulfills both structural and functional roles.

Multiple choice bio-chemistry proteins muscle tissue structure of protein muscle tissues

An example of structural protein is

  1. Myosin

  2. Collagen

  3. Keratin

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Structural proteins are fibrous proteins and form the largest class of proteins measured in terms of their total mass. Structural proteins include myosin, collagen, and keratin. 

Keratins form the protective covering like skin, hair, fur, wool, etc. in all land vertebrates. Equally widespread are the actin and myosin proteins of muscle tissue that play a major role in body movements. In addition, there are the collagens of tendons and hides, which form connective ligaments within the body.
Thus, the correct answer is option (D), 'All of the above'.

Multiple choice zoology immunity phagocytosis cells in immune system immune system, its cells, mediators and antigens

Antigenic determinants are 

  1. Large and complex molecules that are different from those of an organism/host

  2. Proteins or carbohydrates

  3. Recognisable sites over antigens

  4. Specific products of pathogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that binds to the epitope is called a paratope. These epitopes interact with the paratope based on the 3-D surface features and shape or tertiary structure of the antigen.

So, the correct answer is 'Recognisable sites over antigens'.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

In the modern system of nomenclature which one of the following enzyme occupies 6th position _________________.

  1. enzyme occupies 6th position
    (a) Ligase

  2. Isomerase

  3. Lyase

  4. Hydrolase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
According to the modern classification system, enzymes have been classified into six classes:
Class First is Oxidoreductases
Class Second is Transferases.
Class Third is Hydrolase.
Class Fourth is Lyase.
Class Fifth is Isomerase and
Class Sixth is Ligase.
Therefore A is the correct option. 
Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

An organic substance which can withstand environmental extremes and which cannot be degraded by any enzyme is

  1. Sporopollenin

  2. Lignin

  3. Cuticle

  4. Cellulose
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An organic substance which can withstand environmental extremes and which cannot be degraded by an enzyme is sporopollenin. It is the substance present in the exine layer of pollen grains. Due to its presence, fossils of pollen grains can be found. 

So, the correct option is 'Option A'.