Tag: enzymes

Quizzes (4) Questions (199)

Questions Related to enzymes

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

Who discovered the coenzymes?

  1. James Sumner

  2. Fritz Lipmann

  3. Mayerhoff

  4. Eduard Buchner
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Coenzymes are small organic molecules that can be loosely or tightly bound to an enzyme. 
  • Tightly bound coenzymes can be called as prosthetic groups. Coenzymes were discovered by Fritz Lipmann. 
  • His work on the coenzyme was awarded Nobel Prize in Physiology or Medicine, in 1953, for his discovery of coenzyme A and its importance for intermediary metabolism. 
    Hence, option B is the answer.
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

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'.