Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

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

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

  1. Apoenzyme = Holoenzyme+ Coenzyme

  2. Holoenzyme= Apoenzyme + Coenzyme

  3. Coenzyme= Apoenzyme + Holoenzyme

  4. Holoenzyme= Coenzyme+ Apoenzyme
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

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.

  1. IV, III, II, I

  2. III, II, I, IV

  3. IV, II, I, III

  4. II, I, IV, III
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.

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

In biochemical reactions, the enzymes act by

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  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 $CO _{2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

R.Q. stands for

  1. Resistance coefficient

  2. Replicase concentration

  3. Respiratory quotient

  4. Reticular concentration
Reveal answer Fill a bubble to check yourself
C Correct answer
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. 


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

Respiratory quotient is expressed as which of the following equations?

  1. $O _2/CO _2$
  2. $CO _2/O _2$
  3. $O _2/H _2O$
  4. $CO _2 - O _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Lipids are generally

  1. A high energy source

  2. Hydrophobic

  3. Composed of fatty acids

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