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 evs food trends types of ecological pyramids the muscular system and digestive system in human beings introduction to human digestive system

Citrate undergoes dehydration to form unstable compound

  1. iso-citrate

  2. succinate

  3. cis-aconitate

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

In step two, an enzyme called aconitase converts citrate into isocitrate. Next, an isocitrate dehydrogenase enzyme oxidizes isocitrate, a six-carbon molecule, to a five-carbon α-ketoglutarate. The carbon that was lost is released as carbon dioxide and one NADH is also formed.

So, the correct option is, 'Isocitrate'.

Multiple choice bio-chemistry structure and function of cell organelles microbodies living organisms and energy production single membrane bound organelles

The peroxisomes are associated with the phenomenon of

  1. Oxidative anabolism
  2. Degradation of H$ _2$O

  3. Anaerobic respiration
  4. Photorespiration and degradation of H$ _2$O$ _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The peroxisomes are associated with the phenomenon of photorespiration and degradation of H$ _2$O$ _2$. Certain enzymes within the peroxisome, by using molecular oxygen, remove hydrogen atoms from specific organic substrates, in an oxidative reaction, producing hydrogen peroxide.
Photorespiration involves a complex network of enzyme reactions that exchange metabolites between chloroplasts, leaf peroxisomes and mitochondria.

Multiple choice bio-chemistry structure and function of cell organelles microbodies living organisms and energy production single membrane bound organelles

Microbodies resemble mitochondria in 

  1. Using oxygen

  2. Producing reducing power

  3. Having catalase

  4. Formation of ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Microbodies or cytosomes can be defined as cellular organelle found in the plant cells, protozoans and animal cells (liver and kidney cells).
  • The different types of microbodies present within a cell are peroxisomes, glyoxysomes, glycosomes and hydrogenosomes.
  • The main function of microbodies is oxidation of fatty acids, amino acids, purines and alcohol (liver cells) which requires significant amounts of oxygen.
  • Mitochondria are double membrane-bound cellular organelles which are known as the powerhouse of the cell.
  • It creates energy-rich molecules (ATP) for the cell by utilizing oxygen. 
  • So, the correct answer is 'Using oxygen'.
Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

The activity of an enzyme becomes ineffective:

  1. at low temperature

  2. at atmospheric pressure

  3. at high temperature

  4. in aqueous medium.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. 
Enzyme catalysis is unique in its efficiency and high degree of specificity.
  • Enzymes are Highly specific nature.
  • Enzymes are highly active under optimum temperature.
  • Enzymes are highly active under optimum pH.
  • The activity of enzymes gets increased in presence of activators and co-enzymes.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Which of the following is not correct for enzyme catalysis?

  1. The enzyme activity is maximum at optimum pH which is between 5-7.

  2. Each enzyme is specific for a given reaction.
  3. The favourable temperature range of enzyme activity is between 50-60$^{\circ}$C.

  4. The enzymatic activity is increased in presence of certain substances called co-enzymes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. 
Enzyme catalysis is unique in its efficiency and high degree of specificity.
  • Enzymes are Highly specific nature.This says that enzyme is specific for a given reaction.
  • Enzymes are highly active under optimum temperature.The optimum temperature range for enzymatic activity is 298-310K.
  • Enzymes are highly active under optimum pH.Optimum pH level is between 5-7.
  • The activity of enzymes gets increased in presence of activators and co-enzymes.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Enzymes in the living systems:

  1. provide energy

  2. provide immunity

  3. transport oxygen

  4. catalyse biological reactions
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes in the living systems catalyse biological reactions. 


Enzymes speed up the rate of reactions without involving in the reactions. Most enzymes act specifically with only one reactant to produce products. 

Enzymes also regulates from a state of low activity to high activity and vice versa. They acts as a biocatalyst.

Option D is correct.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

The efficiency of an enzyme to catalyse a reaction is due to its capacity to:

  1. Reduce the activation energy of the reaction

  2. Form strong enzyme-substrate complex

  3. Decrease the bond energies of all substrate molecules

  4. Alter the substrate geometry to fit into the shape of the enzyme molecule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are catalysts for biological reactions. Catalysts have the ability to lower the activation energy barrier of the reaction. The more it reduces the activation energy barrier the more efficient it will be.

Hence, option A is correct.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Enzymes in the human body function as a catalyst.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Catalysts increase the rate of a reaction by providing an intermediate to be formed, although the catalyst is left unchanged at the end of the reaction. Catalysts speed up reactions, and without them these reactions might be too slow to sustain life processes.

An enzyme is a protein which has a highly specific amino acid sequence as well as 3D structure allowing it to catalyse reactions. In this sense, they are biological catalysts.

Examples of enzymes are DNA Polymerases (which replicate our DNA to allow our cells to divide) and Kinases (which add phosphate groups to other proteins that might be part of a signalling pathway).

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes
Enzymes also act as a catalyst in biological process.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes also act as catalyst in biological process. Enzymes are biological molecules that act as catalysts and help complex reactions to proceed faster without altering the rate of reaction.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Enzymes, which catalyze biochemical reactions are very complex. They help in the reaction of very specific substances. This suggests that the enzyme and the reacting biochemicals are complementary to one another like a:

  1. dog in his kennel

  2. horse and a rider

  3. lock and key

  4. leaf and a bud
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enzymes are very specific in nature. Only those substrates that can fit into the active site of an enzyme can be bound within it. This specific action is similar to a lock and key where a key(reacting biochemicals) can only be used to actuate a specific lock(enzyme) and not all of them. 

Multiple choice chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

How many molecules of $CO _2$ are formed when one molecule of $C _6H _{12}O _6$ is oxidised in our body?

  1. $4$
  2. $2$
  3. $6$
  4. $8$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In our body, sugar $(C _6H _12O _6)$ is oxidised by the oxygen.WE breath and energy is produced. $CO _2$ is produced which we release into the atmosphere.
The reactioncan be represented by:
$C _6H _12O _6$ $+$ $6CO _2$ $\longrightarrow $  $6CO _2$ $+$ $6H _2O$ $+$ $energy$
Hence, 6 molecules of $CO _2$ is formed.
Multiple choice chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Which step(s) in glycolysis require the input of energy?

  1. The glucose priming step

  2. The phosphorylation of glucose

  3. The phosphorylation of fructose 6-phosphate

  4. All of these steps require the input of energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There are two phases of glycolysis. Priming phase because it requires an input of energy in form of 2 ATPs per glucose molecule and the pay off phase because energy is released in the form of 4 ATPs. The phosphorylation of glucose uses ATP mas the source of phosphate and produce glucose$-6-$phosphate. The second ATP is used in phosphorylation of fructose$-6-$phosphate to fructose$-6-$bisphosphate. All of the given steps requires the input of energy.