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 zoology sustainable agriculture microbes and farming biopesticide environmental protection

Bacillus thuringiensis forms protein crystals which contain insecticidal protein. This protein 

  1. Binds with epithelial cells of mid gut of the insect pest ultimately killing it

  2. Is activated by acidic pH of the gut of the insect pest

  3. Does not kill the carrier bacterium which is itself resistant to this toxin

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

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco dudworm, armyworm), coleopterans (beetals) and dipterans (files, mosquitoes).Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as inactive toxin and is coverted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores which cause cell swelling and lysis and finally cause death of the insect.

So, the correct answer is 'Binds with epithelial cells of midgut of the insect pest ultimately killing it'

Multiple choice zoology sustainable agriculture microbes and farming biopesticide environmental protection

Bt toxin protein crystals present in bacterium Bacillus thuringiensis, do not kill the bacteria themselves because

  1. Bacteria are resistant to the toxin

  2. Toxins occor as inactive protoxins in bacteria

  3. Bacteria enclose toxins in a special sac

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

Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause the death of the insect.

So, the correct answer is 'Toxins occur as inactive protoxins in bacteria'.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Identify the correct statement regarding enzymes.

  1. Enzymes are specific biological catalysts that possess well defined active sites.

  2. Enzymes are normally heterogeneous catalysts that are very specific in their action.

  3. Enzymes are specific biological catalysts that cannot be poisoned.

  4. Enzymes are specific biological catalysts that can normally function at very high temperature (T=1000K).
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Enzyme catalysis is unique in its efficiency and a high degree of specificity.

There are various characteristics are exhibited by enzyme catalysts-
  • Most highly efficient: One molecule of an enzyme may transform one million molecules of the reactant per minute.

  • Highly specific nature: Each enzyme is specific for a given reaction, i.e., one catalyst cannot catalyse more than one reaction. 

  • Highly active under optimum temperature: The rate of an enzyme reaction becomes maximum at a definite temperature, called the optimum temperature.

  • Highly active under optimum pH: The rate of an enzyme-catalysed reaction is maximum at a particular pH called optimum pH, which is between pH values 5-7.

  • Enzymes are normally homogeneous catalysts.

Hence, options A is the correct answers

          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Some drugs do not bind the enzyme's active site, instead, bind to a different site of an enzyme. This site is called:

          1. allosteric site

          2. substrate site

          3. ionic site

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

          A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

          In their catalytic activity, enzymes perform two major functions:

          (i) The first function of an enzyme is to hold the substrate for a chemical
          reaction. Active sites of enzymes hold the substrate molecule in a
          suitable position, so that it can be attacked by the reagent effectively.
          (ii) The second function of an enzyme is to provide functional groups
          that will attack the substrate and carry out chemical reaction.
           Drugs inhibit any of the above mentioned activities of enzymes.
          Drugs inhibit the attachment of substrate on active site of enzymes
          in two different ways;
          (i) Drugs compete with the natural substrate for their attachment
          on the active sites of enzymes. Such drugs are called competitive
          inhibitors.
          (ii) Some drugs do not bind to the enzyme’s active site. These bind to a different site of enzyme which is called allosteric site. This binding of inhibitor at allosteric site changes the shape of the active site in such a way that substrate cannot
          recognise it.

          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Which statement about enzymes is not correct?

          1. Enzymes are in colloidal state.

          2. Enzymes are catalysts.

          3. Enzymes can catalyse any reaction.

          4. Urease is an enzymes.
          Reveal answer Fill a bubble to check yourself
          C Correct answer
          Explanation

          Enzymes are proteins and are giant molecules making them colloidal particles. They are shape selective and catalyzes a specific reaction in which they are suitable.  But they cannot catalyze any reaction.

          Urease is an enzyme and catalyzes the hydrolysis of urea to ammonia and carbon dioxide.

          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Identify the correct statement regarding enzymes.

          1. Enzymes are specific biological catalyst that possess well defined active state.

          2. Enzymes are normally heterogeneous catalyst that are very specific in their action.

          3. Enzymes are specific biological that cannot be poisoned.
          4. Enzymes are specific biological catalyst that can normally function at very high temperature $ ( T \simeq 1000 K).$
          Reveal answer Fill a bubble to check yourself
          A Correct answer
          Explanation
          Enzyme Catalysis - These are catalysts in the living system. Enzymes are substances which by their their presence, alter the rate of anybiological event. These are mainly proteins, and enzyme action is structure specific.
          Enzyme catalysis is the increase in the rate of a chemical reaction by the active site of a protein. The protein catalyst (enzyme) may be part of a multi-subunit complex, and/or may transiently or permanently associate with a Cofactor (e.g. adenosine triphosphate). 
          Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions. A key driver of protein evolution is the optimization of such catalytic activities via protein dynamics.
          They decrease activation energy by providing alternate pathway (enzyme reacts with the substrate to form an intermediate ES complex, which would be impossible in the absence of the enzyme) for the process.
          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Enzymes are ____ specific in action.

          1. highly

          2. not

          3. may be

          4. may not
          Reveal answer Fill a bubble to check yourself
          A Correct answer
          Explanation

          Enzymes are highly specific in action.
          Almost every biochemical reaction is controlled by its own specific enzymes.
          Thus, the enzyme urease catalyzes the hydrolysis of urea. No other enzyme catalyzes this reaction.

          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Active sites are essential for enzyme action.

          1. True

          2. False
          Reveal answer Fill a bubble to check yourself
          A Correct answer
          Explanation
          The active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of residues that form temporary bonds with the substrate (binding site) and residues that catalyse a reaction of that substrate (catalytic site).
          Thus, the active site of the enzyme is responsible for its catalytic action. Thus it is essential for enzyme action.
          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

           Identify the correct statement regarding enzymes:

          1. Enzymes are specific biological catalysts that can normally function at very high temperature

          2. Enzymes are normally heterogeneous catalysts that are very specific in action.

          3. Enzymes are specific biological catalysts that cannot be poisoned

          4. Enzymes are specific biological catalysts that possess well defined active site
          Reveal answer Fill a bubble to check yourself
          D Correct answer
          Explanation

          Enzymes are specific biological catalysts that possess well defined active site.
          Enzymes function at physiological temperature $ \displaystyle \simeq (37 : ^oC)$


          Enzymes can be poisoned using suitable inhibitors.

          Hence, the correct option is $\text{D}$

          Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

          Which of the following statements regarding enzyme inhibition is correct -

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

          2. Non-competitive inhibitors often bind to the
            enzyme irreversibly

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

          4. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate
          Reveal answer Fill a bubble to check yourself
          C Correct answer
          Explanation
          Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme because competitive inhibitor has a similar structure as that of a substrate, so it blocks the active site of an enzyme thereby reducing the production formation.
          Multiple choice bio-chemistry biological molecule lipids and their function some biomolecules lipids

          Identify the incorrectly matched pair.

          1. Ferritin - storage protein

          2. Stearic acid - unsaturated fatty acid

          3. Tyrosine - aromatic amino acid

          4. Vinblastin - alkaloid
          Reveal answer Fill a bubble to check yourself
          B Correct answer
          Explanation

          Fatty acids are of two types based on the single and double bonds in their hydrocarbon chain. The saturated fatty acids have only single bonds in their hydrocarbon chain. These are mostly obtained from an animal source. They exist as solids at room temperature. The unsaturated fatty acids have both the single and double bonds in their hydrocarbon chain. These are mostly derived from plant sources. They exist as a liquid at room temperature.

          A. Ferritin is iron-storing protein.
          B. Stearic acid is a saturated fatty acid made up of 18-carbons.
          C. Tyrosine is an aromatic amino acid with a benzene ring.
          D. Vinblastin is a vinca alkaloid obtained from the plant Vinca rosea.
          Hence, the correct answer is 'Stearic acid- unsaturated fatty acid'

          Multiple choice biology simple nutrients into cells blood and its components components of blood composition of blood

          Most of the blood proteins are

          1. Acidic

          2. Basic

          3. Neutral

          4. All the above in equal proportions
          Reveal answer Fill a bubble to check yourself
          A Correct answer
          Explanation

          Blood proteins are different types of proteins found in blood plasma. These include majorly albumin, globulin, fibrinogen and other regulatory proteins which function as enzymes or hormones. Albumin alone accounts for 55% of the total blood proteins and is acidic in nature. It creates and maintains osmotic pressure of plasma and also helps in the transport of lipids and steroid hormones. Globulin is slightly basic and accounts for 38% of blood proteins. It participates in immune system. Fibrinogen comprises 7% of blood proteins and help in blood clotting.

          Thus, the correct answer is option A. 

          Multiple choice biology simple nutrients into cells blood and its components components of blood composition of blood

          Consider the following four statements and select the correct option stating which ones are true (T) and which ones are false (F)?
          (i) Proteins contribute 6 - 8% of the blood plasma.
          (ii) Plasma contains very high amount of minerals.
          (iii) Plasma without the clotting factors is called serum.
          (iv) Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body.

          1. i - F

            ii - F

            iii - T

            iv - T

          2. i - T

            ii - F

            iii - T

            iv - T

          3. i - T

            ii - T

            iii - F

            iv - F

          4. i - F

            ii - F

            iii - F

            iv - T
          Reveal answer Fill a bubble to check yourself
          B Correct answer
          Explanation

          Blood plasma contains dissolved proteins (6–8%) (i.e.—serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes, hormones, CO$ _2$ and oxygen.

          Though plasma contain substantial amount of minerals but the concentration in terms of percentage can not be defined as 'high amount' in terms of their presence in plasma.
          Blood plasma without clotting factor is called serum.
          Thus, the correct answer is' i - T, ii - F, iii - T, iv - T.'