Biology · Chemistry

Biomolecules and Enzymes

1,501 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 selection and evolution theory of natural selection natural selection evidence for evolution

Nucleoprotein gave most probably the first sign of 

  1. Life

  2. Amino acid

  3. Soil

  4. Sugar
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The giant nucleoprotein molecules were formed by the union of nucleic acid and protein molecules. These nucleoprotein particles were described as free-living genes. Nucleoproteins gave most probably the first sign of life.
  • Hence Nucleoprotein gave most probably the first sign of life.
  • So, the correct answer is 'Life'.
Multiple choice biology selection and evolution theory of natural selection natural selection evidence for evolution

The simple organic compounds that may have first evolved in the direction of origin of life on earth may have been

  1. Protein and amino acid

  2. Protein and nucleic acid

  3. Urea and nucleic acid

  4. Urea and amino acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nucleic acids were formed in a primitive hot soup of sea by the formation of pyrimidine-sugar –phosphate and purine-sugar-phosphate. RNA has the ability of self replication and to catalyze other chemical reactions. Thus, RNA served as an enzyme as well as genetic material in first life forms. Amino acids were formed by condensation, polymerization and redox reactions of hydrocarbons, ammonia and water in Primitive Ocean under influence of energy from UV rays, radiations and lightening. RNA catalyzed polymerization of these amino acids formed polypeptides. The nucleic acid came before proteins. Urea was synthesized as excretory material much later during the evolution of land animals as ammonia is very toxic and requires more water to serve as excretory material. Thus, the correct answer is option B.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Ethylene is metabolic product of

  1. Valine

  2. Serine

  3. Methionine

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

Ethylene is a metabolic product of methionine. It is synthesized from methionine amino acid by methionine cycle or yang cycle. Methionine is first converted to adenosylmethionine. It is then converted to Aminocyclopropane carboxylic acid. It is then oxidized to form ethylene. It is a gaseous plant hormone which stimulates ripening of fruits in plants.

Thus, the correct answer is option C.

Multiple choice parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

What is common among amylase, renin and trypsin?

  1. They are proteins

  2. All these are proteolytic enzymes

  3. These are produced in stomach

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

A) Amylase is produced by buccal cavity, pancreas and intestine and digest starch.

B) Renin is produced by the stomach and helps in the digestion of milk in infants.
C) Trypsin is produced by the pancreas and helps in the digestion of protein.
But one thing is common in all the above three is that they are made up of proteins.
So, the correct option is 'They are proteins'.

Multiple choice parts of the digestive system digestive system of human human digestive system digestion and absorption biology nutrition deficiency diseases digestive system

Semi-indispensible amino acids are

  1. Arginine and histidine

  2. Methionine and threonine

  3. Leucine and isoleucine

  4. Arginine and lysine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Arginine and histidine are considered semi-essential (or semi-indispensable) amino acids because the body can synthesize them, but often not in sufficient quantities during growth or stress.

Multiple choice biology excretion to maintain homeostasis kidney dialysis kidney disorders disorders of kidney

Blackening of urine when exposed to air is a metabolic
disorder in human beings. This is due to

  1. Phenylalanine

  2. Tyrosine

  3. Valine replacing glutamine

  4. Homogentistic acid

  5. Glumine replacing valine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alkaptonuria is an inherited condition that causes urine to turn black when exposed to air. Mutations in the HGD gene cause alkaptonuria. Homogentisic acid, which is produced when phenylalanine and tyrosine are broken down, accumulates in the body. Excess homogentisic acid is deposited in connective tissues, which causes cartilage and skin to darken. Over time, a buildup of this substance in the joints leads to arthritis. Homogentisic acid is also excreted in urine, making the urine turn dark when exposed to air.

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

In what condition hydrolysis of complex organic compounds take place?

  1. Normal conditions

  2. Aerobic Conditions

  3. Anaerobic conditions

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

Hydrolysis of complex organic compounds (like in anaerobic digestion) typically occurs under anaerobic conditions, where oxygen is absent.

Multiple choice zoology excretion and osmoregulation micturition urine and urine formation urine formation

Separation of amino acid into amino and carboxyl group is known as

  1. Deamination

  2. Excretion

  3. Amination

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

Deamination is the process by which amino acids are broken down if there is an excess of protein intake. Deamination takes place in the liver. The amino group is removed from the amino acid and converted to ammonia. Ammonia is toxic to humans, so the enzymes convert it to urea or uric acid by addition of carbon dioxide molecules, which also takes place in the liver. Urea and uric acid is excreted in urine.

Multiple choice evs - i excretion in living organisms other systems in the body excretory system in human human excretory organs

The primary threshold substance are............... .

  1. Urea and uric acid

  2. Potassium and calcium

  3. Glucose and amino acids

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

A substance present in blood is filtered through kidneys. Depending on the concentration they are divided as follows, High threshold substances(such as chlorides or glucose), Low threshold substances (such as phosphates or urea). No-threshold substances (such as creatinine sulfate). The primary threshold substance is Urea and uric acid.

So the correct option is 'Urea and uric acid.'

Multiple choice evs food and health effect on general health diseases caused by changes in lifestyle diet, drugs and disease

The bond that links amino acid to form a protein is known as 

  1. Phosphate bond

  2. Hydrogen bond

  3. Covalent bond

  4. Peptide bond
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The linking of two amino acids is accompanied by the loss of a molecule of water. A series of amino acids joined by peptide bonds form a polypeptide chain, and each amino acid unit in a polypeptide is called a residue.

So, the correct option is 'Peptide bond'.

Multiple choice evs food and health effect on general health diseases caused by changes in lifestyle diet, drugs and disease

An example of conjugated protein is

  1. Albumin

  2. Globulin

  3. Heamoglobin

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

  1. A conjugated protein is a protein that functions in interaction with other (non-polypeptide) chemical groups attached by covalent bonding or weak interactions. Some examples of conjugated proteins are lipoproteins, glycoproteins, metalloproteins etc.
  2.  Haemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of almost all vertebrates as well as the tissues of some invertebrates. 
  3. Haemoglobin contains the prosthetic group known as heme. Each heme group contains an iron ion ($Fe^{2+}$) which forms a coordinate bond with an oxygen molecule ($O _2$), allowing haemoglobin to transport oxygen through the bloodstream. As each of the four protein subunits of haemoglobin possesses its own prosthetic heme group, each haemoglobin can transport four molecules of oxygen. Hence, the example of the conjugated protein is haemoglobin.
So, the correct answer is 'haemoglobin'.

Multiple choice biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

Which of the following is the highest energy rich compound?

  1. Creatinine phosphate

  2. Protein

  3. Carbohydrate

  4. Fat
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Respiration is the oxidation process in which reduced biomolecules like carbohydrates, fats, proteins etc are oxidised to release energy, which can be used for cellular processes. Fats are most reduced biomolecules and their oxidation releases maximum amount of energy. The energy released in oxidation of one gram of fat is twice the energy released in oxidation of one gram of carbohydrate. Hence, carbohydrates are used as an energy reserve biomolecules in living systems.