Tag: biomolecules: chemical constituents of living cells

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Questions Related to biomolecules: chemical constituents of living cells

Multiple choice bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

Two important processes in a cell, which take place outside the membrane bound organelles, are

  1. Enzyme synthesis and DNA replication

  2. Nucleotide synthesis and mutation

  3. Fatty acid synthesis and spindle assembly

  4. Glycolysis and photophosphorylation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The process of fatty acid synthesis takes place in the cytoplasm and not in a membrane-bound organelle. Also, spindle assembly takes place in the centrioles which also lack a membrane.

So, the correct answer is 'fatty acid synthesis and spindle assembly'.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Vitamin as a building block is present in ___________.

  1. Apoenzyme

  2. Alloenzyme

  3. Metallic ion

  4. Lipoprotein

  5. Coenzyme
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The vitamins act as part of coenzymes, small molecules that combine with an enzyme to make it active.

Vitamin B 6 assists in the synthesis of new proteins in the cell by assembling protein building blocks called amino acids.

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

Biological catalysts are called as

  1. Auxins

  2. Gibberellins

  3. Enzymes

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

Enzymes are biocatalyst. These are proteinaceous substances that are capable of catalysing chemical reactions of biological systems without themselves undergoing any change. The term enzymes were first used by Kuhne in 1877.

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

What is common among amylase, renin and trypsin?

  1. These are all proteins

  2. These are proteolytic enzymes

  3. These are produced in stomach

  4. These act at a pH lower than 7
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Amylase is a protein-based enzyme that is secreted by the salivary glands of mouth and is involved in the breakdown of starch. It functions in a neutral pH (pH 7). Renin is also a protein enzyme secreted in the stomach and involved in the coagulation of milk. It functions in a acidic pH. Trypsin is also a protein enzyme that is produced in the small intestine and is a proteolytic enzyme. It also functions in acidic pH. So, the correct answer is 'These are all proteins'.

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

At boiling temperature, an enzyme is

  1. Denatured

  2. Unaffected

  3. Inactivated

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

The activity of an enzyme can be affected by a change in the conditions which can alter the tertiary structure of the protein. These include temperature, pH, change in substrate concentration or binding of specific chemicals that regulate its activity. Enzymes generally function in a narrow range of temperature and pH. Each enzyme shows its highest activity at a particular temperature and pH called the optimum temperature and optimum pH. Activity declines both below and above the optimum value. Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat. At boiling temperature all proteins including enzymes are denatured.

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.