Tag: biology

Questions Related to biology

With reference to enzymes, which one of the following statements is true?

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

  1. Apoenzyme = Holoenzyme+ Coenzyme

  2. Holoenzyme= Apoenzyme + Coenzyme

  3. Coenzyme= Apoenzyme + Holoenzyme

  4. Holoenzyme= Coenzyme+ Apoenzyme

Show answer
Correct Option: B
Explanation:
Enzymes work efficiently in association with various factors which enhances it's activity. These factors may be;

Coenzymes are organic molecules that are mostly derivatives of vitamins soluble in water by phosphorylation. Example of coenzyme include thiamine pyrophosphate (TPP), flavin adenine dinucleotide (FAD), biotin

Apoenzyme is an inactive form of enzyme lacking the association of coenzyme and/or cofactors. Activation of the enzyme occurs upon binding of an organic or inorganic cofactor.

Holoenzyme is a complete and catalytically active form of enzyme. An apoenzyme together with its cofactor is holoenzyme.  Examples of holoenzymes include DNA polymerase and RNA polymerase which contain multiple protein subunits.

So the correct option is 'Holoenzyme= Apoenzyme + Coenzyme'.

Arrange the steps of catalytic action of an enzyme in order and select the correct option.
I.   The enzyme release the products of the reaction      and the enzyme is free  to bind to another                substrate.
II.  The active site of enzyme is in close proximity of      the substrate and breaks the chemical bonds of     the subtrate.
III. The binding of sustrate induces the enzyme to          alter its shape fitting more tightly around the           sustrate. 
IV.The substrate binds to the active site of the              enzyme.

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

  1. IV, III, II, I

  2. III, II, I, IV

  3. IV, II, I, III

  4. II, I, IV, III

Show answer
Correct Option: A
Explanation:
Four Steps of Enzyme Action:
1) The enzyme and the substrate are in the same area. Some situations have more than one substrate molecule that the enzyme will change.
2) The enzyme grabs on to the substrate at a special area called the active site. A process called catalysis.
3) The binding of substrate induces the enzymes to alter its shape to fit around the substrate. 
4) The enzyme breaks the chemical bonds of the substrate and releases the product of the reaction and the enzyme is free to bind to another substrate.

So, the correct option is 'IV, III, II, I'.

The inorganic catalyst attached to enzymes is called

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

  1. Apoenzyme

  2. Lysozyme

  3. Activator

  4. Inhibitor

Show answer
Correct Option: C
Explanation:

An activator is an inorganic catalyst attached to enzymes. The bind to the enzyme and increase its activity. 

So, the correct option is 'Activator'. 

In biochemical reactions, the enzymes act by

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

  1. By decreasing the energy of the reactants

  2. By increasing the activation energy of the reaction

  3. By decreasing the activation energy of the reaction

  4. By increasing the energy of the products of the reaction

  5. By decreasing the energy of the products of the reaction

Show answer
Correct Option: C
Explanation:

The minimum energy requirement that must be met for a chemical reaction to occur is called the activation energy. The activation energy is the energy difference between the reactants and the activated complex, also known as transition state. In a chemical reaction, the transition state is defined as the highest-energy state of the system. If the molecules in the reactants collide with enough kinetic energy and this energy is higher than the transition state energy, then the reaction occurs and products form. In other words, the higher the activation energy, the harder it is for a reaction to occur and vice versa. However, if a catalyst is added to the reaction, the activation energy is lowered because a lower-energy transition state is formed. Enzymes can be thought of as biological catalysts that lower activation energy. Enzymes are proteins or RNA molecules that provide alternate reaction pathways with lower activation energies than the original pathways. Enzymes affect the rate of the reaction in both the forward and reverse directions; the reaction proceeds faster because less energy is required for molecules to react when they collide. Thus, the rate constant (k) increases.
So, the correct answer is option C.

Respiratory quotient (R. Q.) is defined as the

biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

  1. Vol. of $O _{2}$ / vol. of $CO _{2}$

  2. Vol. of $CO _{2}$ / vol. of $O _{2}$

  3. Vol. of $O _{2}$ / vol. of $N _{2}$

  4. Vol. of $N _{2}$ / vol. of $CO _{2}$

Show answer
Correct Option: B
Explanation:

The volume of carbon dioxide released and oxygen consumed in the process of respiration is called as respiratory quotient or R.Q of that substrate.

R.Q. stands for

biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

  1. Resistance coefficient

  2. Replicase concentration

  3. Respiratory quotient

  4. Reticular concentration

Show answer
Correct Option: C
Explanation:

Respiratory quotient (RQ) is the ratio of the volume of carbon dioxide released to the volume of oxygen taken in respiration in the given period of time at standard temperature and pressure. 

RQ = CO2 eliminated / O2 consumed

Name of the substance Respiratory Quotient
Carbohydrates 1
Proteins 0.8 - 0.9
Triolein 0.7
Tripalmitin (Fat) 0.7
Malic acid 1.33
Tartaric acid 1.6
Oxalic acid 4.0

Thus, the correct answer is option C. 


Respiratory quotient is expressed as which of the following equations?

biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

  1. $O _2/CO _2$

  2. $CO _2/O _2$

  3. $O _2/H _2O$

  4. $CO _2 - O _2$

Show answer
Correct Option: B
Explanation:

During aerobic respiration, $O _2$ is consumed and $CO _2$ is released. The ratio of the volume of $CO _2$ evolved to the volume of $O _2$ consumed in respiration is called the respiratory quotient (R.Q) or respiratory ratio.  Thus the following expression is used to calculate the value of R.Q.
RQ= volume of $CO _2$ evolved/ volume of $O _2$ consumed.

Which of the following is not a source of fats obtained from animals?

biology a healthy diet minerals and vitamins nutrition and diet role of various nutrients

  1. Butter

  2. Cream

  3. Coconut oil

  4. Cod liver oil

Show answer
Correct Option: C
Explanation:
  • Coconut oil is a source of fat obtained from plants, while rest all i.e. butter, cream, and cod liver oil are obtained from animals. Thus option C is the correct answer. 

Which of the following are sources of fats?

biology a healthy diet minerals and vitamins nutrition and diet role of various nutrients

  1. Oil, ghee, butter

  2. Eggs

  3. Rice, wheat, potato

  4. Iron and calcium

Show answer
Correct Option: A
Explanation:

Oil, ghee and butter source of fats; egg source of proteins; rice, wheat, potato source of carbohydrates; iron and calcium are essential minerals.

Lipids are generally

biology a healthy diet minerals and vitamins nutrition and diet role of various nutrients

  1. A high energy source

  2. Hydrophobic

  3. Composed of fatty acids

  4. All of the above

Show answer
Correct Option: D
Explanation:

Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. They are the most calorigenic among the biomolecules. Chemically lipids are hydrophobic.