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 biology the life cycle of animals how do animals reproduce? excretory, nervous and reproductive system structure and functions of living organisms -ii

Cry gene which synthesize crystal protein is isolated from

  1. Bacillus thuringiensis

  2. Rhizobium

  3. Bacillus polymyxa

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

Bacillus thuringiensis (Bt) is a Gram-positive bacterium that produces crystals during sporulation. These crystals comprise ~130 kDa protoxins called crystal proteins which are potent and highly specific insecticides. Once ingested by specific host, these crystals dissolve in the alkaline conditions of the gut thereby activating the protoxins. The active toxins then bind to receptors on midgut epithelial cells, become inserted into the plasma membrane where they form pores leading to cell death through osmotic lysis. Option A is the correct answer.

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology
Biomolecules are

  1. inorganic materials

  2. organic materials

  3. all the carbon compounds obtained from living tissues

  4. only DNA and RNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Biomolecules are basically all the carbon compounds obtained from the living tissue. All the major components that make up a living being that is the carbohydrate, proteins, lipids contain carbon in one form or the other.

Carbon is the structural as well as the functional unit of the basic framework of the cell.

So, the correct option is 'all the carbon compounds obtained from living tissues'

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

Cellular micromolecules are

  1. Amino acids, Water, Minerals and Sugars

  2. Glycogen, Amino acids, Minerals and Nucleotides

  3. Water, Minerals, Nucleic acids, Amino acids and Nucleotides

  4. Sugars, Water, Minerals, Proteins and Nucleotides
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The cellulose micromolecules are small in size and have low molecular weights which is less than 1000 daltons. They have simple molecular structure and often high solubility in the intracellular fluid. These include inorganic compounds such as water, mineral salts, and gases as well as organic compounds such as sugars, lipids, amino acids and nucleotides. The small molecules are the substrates and products of metabolism in the cell. The micromolecules act as building blocks for the macromolecules. 

Thus, the correct answer is option A. 

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

Pick out the wrong statement.

  1. Amino acids are substituted methanes.

  2. Is a trihydroxy propane.

  3. Lysine is a neutral amino acid.

  4. Lecithin is a phospholipid.

  5. Adenosine is a nucleoside.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Amino acids are amphoteric compounds having a carboxylic group, amino group, hydrogen and a substituent group bonded to same carbon atom called the $\alpha$-carbon atom. The substituent group may be having one or more carboxylic groups or amino groups. In case the substituent group is having an extra amino group, the amino acid will be having more than one amino groups and will be positively charged at neutral pH and will be a basic amino acid like lysine and arginine.

Similarly if substituent group carries extra carboxylic group, the amino acid will carry negative charge at neutral pH and will be an acidic amino acid like aspartic acid and glutamic acid.
In case the substituent group does not carry extra carboxylic or amino groups the amino acid is neutral amino acid example glycine, alanine, valine.

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

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

  1. Decrease metabolism.

  2. Are conjugated proteins.

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

  4. Help in regulating metabolism.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes, vitamins and hormones are critical to the central role of these elements in the metabolism. Some enzymes in addition to the proteinaceous part require an additional organic molecule coenzyme. Most of the coenzymes are derived from vitamins. Hormones are chemically a diverse group. They may be amines or steroids or peptides. The hormones regulate body metabolism over a longer duration and slowly effect the developmental changes during the development of an organism. The main difference between the enzyme (coenzyme) and hormones is the time scale of their operation. Both are similar in their role in regulating body metabolism.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Protein rich pulses have R.Q. will be

  1. One

  2. More than one

  3. Less than one

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

The respiratory quotient (R.Q) is the ratio of $CO _2$ produced to $O _2$ consumed, while food is being metabolized.
RQ = $CO _2$ eliminated / $O _2$ consumed
R.Q for proteins is less than 1. Because, amount of $O _2$ consumed is higher than amount of $CO _2$ eliminated. So, protein rich pulses have R.Q less than 1. Thus, option C is correct and other options are incorrect.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

The value of R.Q. for proteins is

  1. Equal to one.

  2. More than one.

  3. Less than one.

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

During aerobic respiration, $O _2$ is consumed and $CO _2$ is released. The ratio of the volume of $CO _2$ evolved to the volume of $O _2$ consumed in respiration is called the respiratory quotient (R.Q) or respiratory ratio. The respiratory quotient depends upon the type of respiratory substrate used during respiration. When carbohydrates are used as substrate and are completely oxidised, the RQ will be 1, because equal amounts of $CO _2$ and $O _2$ are evolved and consumed, respectively. When fats are used in respiration, the RQ is less than 1. When proteins are respiratory substrates the ratio would be about 0.9.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Which statement regarding enzyme inhibition is correct?

  1. Competitive inhibition occurs when a substrate competes with enzyme for binding to inhibitor protein

  2. Competitive inhibition occurs when the substrate and the inhibitor compete for active site on the enzyme

  3. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate

  4. Non-competitive inhibitors often bind to the enzyme irreversibly
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A molecule similar to substrate competes with the substrate for active site. Such molecules are known as inhibitor. The presence of the inhibitor decreases availability of the active site for the substrate and further decreases the rate of reaction. This inhibition is known as competitive inhibition.
For example, malonate acts as a inhibitor which  competes with the succinate and prevents its attachment to the enzyme succinate dehydrogenase.
So, the correct answer is option B.
Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Identify the correct statement regarding enzyme inhibition.

  1. Non-competitive inhibition of an enzyme can be overcomed by adding large amount of substrate.

  2. Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.

  3. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.

  4. Non-competitive inhibitors often bind to the enzyme irreversibly.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Competitive inhibition is the inhibition of an enzyme by an inhibitor which has structural similarity to the active site and thus competes with the substrate for binding with the active site. Competitive inhibition is a reversible inhibition and depends on the relative concentration of substrate and inhibitor.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Which of the following is true?
Non-competitive inhibitor differs from a competitive inhibitor in that it

  1. Reduces the affinity of substrate for enzymes
  2. Does not alter K$ _m$

  3. May attach it self to the enzyme at a site other than the active site

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A non-competitive inhibitor is one that binds to a site distinct from the site which binds the substrate; inhibitor binding does not block substrate binding or vice versa. The enzyme is inactivated when inhibitor is bound, whether or not substrate is also present. The inhibitor effectively lowers the concentration of active enzyme and hence, lowers the apparent V$ _{max}$. There is often little or no effect on K$ _m$.

Multiple choice biology metabolism, cell respiration, and photosynthesis metabolism enzymes carbohydrate metabolism

Which of the following statements regarding enzyme inhibition is correct?

  1. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate.

  2. Competitive inhibition is seen, when a substrate competes with an enzyme for binding to an inhibitor protein.

  3. Competitive inhibition is seen, when the substrate and the inhibitor compete for the active site on the enzyme.

  4. Non-competitive inhibitors often bind to the enzyme irreversibly.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A competitive inhibitor is a reversible inhibition where the inhibitor competes with the substrate for the active site of an enzyme. While the inhibitor occupies the active site it prevents binding of the substrate to the enzyme. Many competitive inhibitors are compounds that resemble the substrate and combine with the enzyme to form an enzyme inhibitor complex, but without leading to catalysis. Even fleeting combinations of this type will reduce the efficiency of the enzyme. By taking into account the molecular geometry of inhibitors that resemble the substrate, we can reach conclusions about which parts of the normal substrate bind to the enzyme. Competitive inhibition can be analyzed quantitatively by steady-state kinetics.