Tag: biomolecules: chemical constituents of living cells

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Questions Related to biomolecules: chemical constituents of living cells

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

Biocatalysts were found accidently in Yeast extract by

  1. Sumner

  2. Kuhne

  3. Buchner

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

Biocatalysts were found accidentally in yeast extract by Buchner in 1897. He prepared a yeast extract and added sugar solution to it. After sometime he noticed the alcohol formation in the extract which was a sign of fermentation which took in presence of enzyme. Later on, Sumner crystallized an enzyme known as urease and reported that all enzymes are protein.

So, the correct answer is option C.

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

Enzyme action comes to a stop when hydration decreases in maturing seeds to

  1. $50 - 60$%
  2. $30 - 45$%
  3. $25 - 30$%
  4. $10 - 20$%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

As seeds mature, they undergo dehydration. Enzyme activity is significantly reduced or stopped when the moisture content drops to a very low level, typically around 10-20 percent, to induce dormancy.

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

The action of lysozyme is

  1. Physiological

  2. Anatomical

  3. Morphological

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

Lysozyme are also reffered as muramidase. They are glycoside hydrolases. They catalyzes hydorlysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetly-D-glucosamine residues in peptidoglycan thus they can dissolve bacterial cell wall. It is present  in a number of secretions, such as tears, saliva, human milk and mucus. So, its function is physiological.
Thus, the correct answer is option (A).

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

Select the correct option: 

Enzymes catalyze the biochemical reactions by .......... the activation energy.

  1. lowering

  2. increasing

  3. unaltering

  4. either (a) or (b)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are macromolecular biological catalysts. which accelerates chemical reactions. Catalysts lower the activation energy (energy required to start a reaction.) for reactions. The lower the activation energy for a reaction, the faster the rate.

So, the correct answer is 'lowering'.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology
Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, and addition of groups to double bonds, are called

  1. Ligase

  2. Lyase

  3. Hydrolase

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

Lyases enzymes catalyse the breakage of specific covalent bonds and removal of group with out hydrolysis producing double bonds or removal of double bonds by adding group,e.g., histidine decarboxylase that splits $C-C$ bond of histidine,forming $CO _2$ and histamine.

${\overset{X}{\overset{|}C}}-{\overset{Y}{\overset{|}C}} \xrightarrow{lyase}X-Y+C=C$

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

Relationship between genes and enzymes was discovered by

  1. Waldeyer

  2. W. Johannsen

  3. Bridges

  4. Beadle and tatum
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sir Archibald Garrod proposed that one enzyme is encoded by one gene. This hypothesis called One gene One enzyme hypothesis, was experimentally proved by Beadle and Tatum by using bread mould Neurospora. Beadle and Tatum showed bread mould mutants that were unable to make specific amino acids. In each one, a mutation had disrupted an enzyme needed to build a certain amino acid. This was caused due to specific gene mutation.

Hence, the correct answer is 'Beadle and Tatum'

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

The hydrolytic enzymes acting at low pH are

  1. $\alpha$-amylases

  2. Hydrolases

  3. Proteases

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

A protease (also called peptidase or proteinase) is any enzyme that performs proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein. Proteases may be classified by the optimal pH in which they are active: acid proteases or neutral proteases or basic proteases.