Biology · Chemistry

Biomolecules and Enzymes

1,432 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 botany energy flow in an ecosystem biogeochemical cycle nutrient cycles species, communities and ecosystems

Living organisms require ............. to produce proteins and nucleic acids in their body.

  1. Oxygen

  2. Nitrogen

  3. Carbon

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

Nitrogen is essential for producing proteins (amino acids contain nitrogen) and nucleic acids (DNA/RNA nitrogenous bases). While carbon and oxygen are also crucial, nitrogen is specifically required for these macromolecules. Water is a solvent, not a building block.

Multiple choice zoology movement and locomotion in man bones and movements our skeletal system and the skin human skeleton system

Which one of the following is the correct matching of three items and their grouping category?

  1. Actin, myosin, rhodopsin : Muscle proteins

  2. Cytosine, uracil, thiamine : Pyrimidines

  3. Malleus, incus, cochlea : Ear ossicles

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Actin and myosin are muscle proteins, while rhodopsin is a photoreceptor protein. 

Cytosine, uracil, and thiamine are pyrimidines, that along with purines make up the genetic material. 
Malleus, incus, and stapes together form the ear ossicles. 

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

Which of the following statements is not correct?

  1. All enzymes are proteins.

  2. All enzymes are biocatalysts.

  3. All proteins are enzymes.

  4. All enzymes are thermolabile.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

All proteins are not enzymes. Proteins are most versatile biochemicals fulfilling a diverse set of structural and functional roles. For example, haemoglobin, keratin, albumin, etc., are all proteins but are not enzymes. Similarly, all enzymes are not proteins. In fact, most of the enzymes, are proteinaceous in nature. But ribozymes are not proteins in nature, they are catalytic RNAs.

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

Enzymes are basically _________.

  1. Fat

  2. Protein

  3. Nucleic acid

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

Enzymes are the specialized proteins which are capable of catalyzing reactions in the living cells.

These enzymes are structurally different and have specific sites which helps the enzyme to bind to a substrate for the catalyzation.
But there are some exceptions, that enzymes such as Ribozymes are not made up of proteins and they are made up of Nucleic acids.
Therefore, enzymes are basically proteins.

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

Three of the following statements about enzymes are correct and one is wrong. Which one of the following is wrong?

  1. Enzymes require optimum pH for maximal activity.
  2. Enzymes are denatured at high temperature but in certain exceptional organisms they are effective even at temperatures 80-90$^o$C.

  3. Enzymes are highly specific.

  4. Most enzymes are proteins but some are lipids.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are the biological catalyst which catalyzes biological reactions within a narrow range of temperature and pH. Certain thermophiles have enzymes which remain functional even at very high temperatures. Most of the enzymes are proteins in nature but a few enzymes are RNA in nature. They are called as catalytic RNAs or ribozymes.

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

Part of enzyme which combines with non-protein part of form functional enzyme is

  1. Apoenzyme

  2. Coenzyme

  3. Prosthetic group

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

The conjugate protein consists of two parts protein and non-protein part. Non-protein part is the cofactor and protein part is apoenzymes. Complete conjugate protein is known as Holoenzymes. Apoenzyme is an inactive enzyme. Thus, the correct option is D.

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

Which one value is required for better enzymatic action?

  1. High K$ _i$
  2. Low K$ _i$
  3. Low K$ _m$
  4. High K$ _m$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A constant indicating the substrate concentration at which an enzyme catalysed reaction attains half its maximum velocity or 1/2 V$ _{max}$ is known as Michaelis-Menten constant or K$ _m$. Lower K$ _m$ indicates more affinity between the enzyme and substrate and consequently higher reaction rates.

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

Enzymes are basically made of

  1. Nucleic acids

  2. Proteins

  3. Fats

  4. Vitamins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated by the addition of an organic or inorganic cofactor. The holoenzyme is defined as apoenzyme in combination with the cofactor. 
So, the correct answer is option B.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Which is not a trait of enzymes?

  1. Proteinaceous nature

  2. Specific in nature

  3. Speed up rate of biochemical reaction

  4. Used up in reaction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated by the addition of an organic or inorganic cofactor. It is specific in nature as specific substrate bind at the active site of a particular enzyme. It increases the rate of chemical reactions without being used up. The enzymes lower the activation energy and lead to the formation of activated complex, which is also known as transition state and finally changes to the product.

So, the correct answer is option D.

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

Which is wrong about enzymes?

  1. Enzymes are mostly proteins but some are lipids also

  2. Enzymes are highly specific

  3. Enzymes require optimum pH and temperature for maximum activity

  4. Enzymes are denatured at high temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Enzymes are made up of proteins which accelerates the rate of the reaction. It lowers the activation energy and converts the reactants into the substrate. The increased temperature increases the kinetic energy of the enzymes which further accelerates the activity of the enzyme but at the higher temperature, it gets denatured as the peptide bonds between the proteins molecules breaks which disrupts the structure of enzymes. 
Enzymatic activity depends on specific pH. pH at which the enzyme has maximum activity is known as optimum pH. The change in pH changes the shape of the enzyme which prevents the attachment of the substrate at the active site and terminates the reaction. 
Enzymes are specific in nature. It forms an enzyme-substrate complex by attaching to the active site of the enzyme which depends specifically on the shape of the active site and the substrate molecules.
So, the correct answer is option A.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Which is true about enzymes?

  1. All enzymes are not proteins

  2. All enzymes are vitamins

  3. All enzymes are proteins

  4. All proteins are enzymes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are protein in nature. But some enzymes like ribozymes and ribonuclease are RNA based enzymes. It is also known as ribonucleic acid enzymes. These are RNA molecules which helps in the catalysis of a particular reaction. It was discovered in year 1982. The RNA can act as both genetic material and can act as a biocatalyst but different from protein-based enzymes. It acts as a part of ribosome which attaches to the amino acid during protein synthesis. Thomas R. Cech and Sidney Altman discovered catalytic properties of RNA. So, the correct answer is option A.

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

Enzyme generally have?

  1. Same pH and temperature optima

  2. Same pH but different temperature optima

  3. Different pH but same temperature optima

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

The optimum temp of enzymes is 20-35°C. They become inactivated at very low temperature and denatured (destroyed) at very high temp i.e. greater than 45°C. Low molecular weight enzymes are comparatively more heat stable. In archaebacterium Pyrococcus furiosus, the optimum temperature of hydrogenase is greater than 95°C. This heat-stable enzyme enables Pyrococcus to grow at 100°C. The optimum pH of most endoenzyme is pH 7.0 (neutral pH). However, digestive enzymes can function at different pH. For example, salivary amylase act best at pH 6.8, pepsin act best at pH2 etc. Any fluctuation in pH from the optimum causes ionization of R-groups of amino acids which decrease the enzyme activity.

So the correct option is 'different pH but same temperature optima' 

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

Serine proteases are called so because they

  1. They require serine for their activity

  2. cleave after serine residues in the substate

  3. Are inhibited by the presence of free serine

  4. Have a serine residue at their active sire
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Serine proteases are enzymes that cleave peptide bonds in proteins, in which serine serves as a nucleophilic amino acid at enzyme's active site. Serine proteases are responsible for coordinating various physiological functions including digestion, immune response, blood coagulation, and reproduction. Hence, serine proteases are called so because they require serine for their activity.

So, the correct answer is 'They require serine for their activity'.