Biology

Cellular Respiration and Enzymes

1,551 Questions

Explore key concepts of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain. These questions also cover ATP production, anaerobic respiration, and essential metabolic pathways. This topic forms a core part of the biology syllabus for many competitive examinations.

Glycolysis and metabolic pathwaysKrebs cycle processesElectron transport chainATP production countAnaerobic respiration products

Cellular Respiration and Enzymes Questions

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The cytochromes are 

  1. Peroxidase

  2. Iron protoporphyrin

  3. Pyridine nucleotides

  4. Metal containing flavoproteins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cytochromes are iron-porphyrin or heme proteins discovered by MacCunn. Cytochromes are bound to inner mitochondrial membrane and are primarily responsible for the generation of ATP via mitochondrial electron transport system. Whereas all other cytochromes have iron only, the cytochrome a possesses both iron and copper. With iron it picks up electrons and through copper it hands over electrons to oxygen.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Which one of them catalyzes oxidation-reduction reactions?

  1. Oxidase

  2. Oxidoreductase

  3. Oxygenase

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

Certain enzymes carry oxidation reduction reactions. Oxidation is defined as the chemical process which involves loss of electron whereas reduction is the process in which a substrate accepts electron.
An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O$ _2$ (as in air) to it.

An oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor.
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction, especially one involving molecular oxygen (O$ _2$) as the electron acceptor.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes that catalyse endergonic synthesis, coupled with exergonic hydrolysis of ATP are

  1. Ligases

  2. Isomerases

  3. Lyases

  4. Transferases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
There are six major classes of enzymes, as follows:
(1) Oxidoreductases - Catalyze oxidationreduction reactions.
(2) Transferases - Catalyze the transfer of a functional group from a donor molecule to an acceptor molecule.
(3) Hydrolases - Catalyze hydrolysis reactions. 
(4) Isomerases - Catalyze conversion of a molecule from one isomeric form to another.
(5) Ligases - Ligases or synthetases are enzymes that catalyse endergonic synthesis, coupled with the exergonic hydrolysis of ATP
(6) Lyases - Catalyze certain reactions in which double bonds form or break.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzyme concerned with transfer of electrons are

  1. Hydrolase

  2. Dehydrogenase

  3. Transaminase

  4. Protease
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Dehydrogenases are the enzymes which catalyze oxidation-reduction reactions by addition or removal of electrons. These reactions are used to synthesize reduced coenzymes like NADH$ _2$ and FADH$ _2$. For example phosphoglyceraldehyde dehydrogenase.

So, the correct answer is 'Dehydrogenase'.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes catalysing removal of groups and formation of double bond are

  1. Transferases

  2. Ligases

  3. Lyases

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

Lyase is the enzyme by which the chemical bonds are broken down by the process other than hydrolysis and oxidation. It allows the formation of new bond. 

Ligase are the enzyme which catalyzes the joining of two large molecules by formation of chemical bonds.
Oxoreductase are the enzyme which catalyzes the oxidation and reduction reaction.

Transferase involves the transfer of functional group from one molecule to the other.
So, the correct answer is option C.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes which catalyse reactions involving changes in structure of a molecule are

  1. Ligases

  2. Isomerases

  3. Hydrolases

  4. Transferases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Enzyme catalyzing optical or geometrical rearrangement of atomic groupings without altering molecular weight or number of atom is isomerase. It converts into from one isomer to the other isomer by changing the intramolecular arrangement by forming or breaking the bond. For, example glucose 6 phosphate is changed to fructose 6 phosphate by enzyme isomerase during the process of glycolysis.
Ligase is a enzyme which is used to join two molecules by establishing covalent bonds. Two DNA molecules are joined together by phosphodiester bond in presence of DNA ligase. The enzyme cannot be used for the blunt end of the DNA fragments. The nature of the bond is covalent as it involves the exchange of electrons.
Hydrolase are the enzyme which catalyses the splitting of compounds by addition of water.
Transferases helps to transfer functional group from one molecule to another.
So, the correct answer is option B.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Name the type of enzyme involved in the following reaction $S-G+{S}^{'} \longrightarrow S-{S}^{'}+G$.

  1. Dehydrogenase

  2. Transferase

  3. Hydrolase

  4. Lyase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transferase is an enzyme that transfers a specific functional groups from one molecule to another. 

Enzyme catalyzing optical or geometrical rearrangement of atomic groupings without altering molecular weight or number of atom is isomerase. It converts into from one isomer to the other isomer by changing the intramolecular arrangement by forming or breaking the bond. 
Dehydrogenase is an enzyme which participates in the oxidoreductase reaction by using a electron acceptor.
Hydrolase are the enzyme which catalyses the splitting of compounds by addition of water.
Lyase is the process by which the chemical bonds are broken down by the process other than hydrolysis and oxidation. It allows the formation of new bond. 
So, the correct answer is option B.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzyme involved in transfer of electrons belongs to 

  1. Hydrolase

  2. Desmolase

  3. Transaminase

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

Dehydrogenase is an enzyme which participates in the oxidoreductase reaction by using an electron acceptor. It is involved in the transfer of electrons because it oxidizes a substrate by reducing it which means it transfers the electron from the substrate to an electron acceptor. Succinate dehydrogenase is an enzyme which is present in the inner mitochondrial membrane. It catalyzes the oxidation of succinate to fumarate.

So, the correct answer is option D.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Lactose metabolising enzyme, produced in the presence of lactose only is

  1. Inducible enzyme

  2. Repressible enzyme

  3. Regulatory enzyme

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

Inducible enzymes are synthesized only in the presence of their specific substrate, such as the enzymes of the lac operon in the presence of lactose.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes catalysing removal of group and formation of double bonds are 

  1. Ligases

  2. Lyases

  3. Transferases

  4. Oxidoreductases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lyases is an enzyme which catalyses the joining of specified molecules or groups by a double bond. Lyases catalyze reactions where functional groups are added to break double bonds in molecules or the reverse where double bonds are formed by the removal of functional groups. So, the correct answer is option B.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The catalytic efficiency of two different enzyme can be compared by the:

  1. The Kim value

  2. The pH optimum value

  3. Formation of the product

  4. Molecular size of the enzyme
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The $K _m$ is also known as Michaelis-Menten constant. It represents the substrate concentration at which the rate of a reaction is half the maximum rate. It is an important parameter to compare catalytic efficiency of two enzymes. Lower the $K _m$ , higher will be the catalytic rate and vice-versa.
Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

The enzyme which has EC number 4.2.1.7 is assigned to which of the following classes of enzyme?

  1. Hydrolases

  2. Lyases

  3. Isomerases

  4. Ligases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The EC number 4.2.1.7 is assigned to the enzyme named altronate dehydratase or D-altronate hydro-lyase. This enzyme catalyses the dehydration of D-altronate and results in the formation of 2-dehydroxy-3-deoxy-D-gluconate and water. 

Thus, the answer is B, i.e., the enzyme which has EC number 4.2.1.7 is assigned to the class of Lyases.

Multiple choice enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Enzymes that catalyse inter-conversion of optical, geometrical or positional isomers are

  1. Ligases

  2. Lyases

  3. Hydrolases

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

Ligases are the enzymes which catalyze joining together of two DNA segments. Lyases catalyze the breaking of chemical bonds without hydrolysis while hydrolases catalyze hydrolytic cleavage of bonds. Isomerases catalyze interconversion of optical, geometrical or positional isomers of a particular enzyme.

Multiple choice bio-chemistry cell structure membrane bound organelles cell: size and differentiation microscopy

In condensed state of mitochondria

  1. ATP Synthesis is reduced

  2. Oxidative phosphorylation and ETS occurs at faster rate

  3. Intermembrane space becomes smaller

  4. Core or matrix is enlarged
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

One of the two morphological forms of a mitochondrion is 'condensed' form observed in mitochondria with high respiratory rates (ATP formation is high with increased rates of Kreb's cycle, ETS, and oxidative phosphorylation). In this type of confirmation, the matrix volume inside inner membrane is not very large causing the inner membrane to move away from outer membrane causing the intermembrane space to swell except at the site of where two are connected. Thus considering all the details about this form of the mitochondrion.

The correct answer is 'Oxidative phosphorylation and ETS occur at a faster rate'.