Biology

Cellular Respiration and Enzymes

1,721 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 parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Which is required in glycolysis?

  1. ATP, ADP, $NAD^+$, Glucose, cytoplasmic enzymes
  2. $FAD^+$, ADP, ATP, Glucose, cytoplasmic enzymes
  3. $NADP^+$, ATP, GTP, Glucose, cytoplasmic enzymes
  4. $NAD^+$, $NADP^+$, ATP, Glucose, cytoplasmic enzymes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Glycolysis occurs in the cytoplasm of the cell and is present in all living organisms. In this process, glucose undergoes partial oxidation to form two molecules of pyruvic acid.
  • Glycolysis requires specific ingredients to work. The inputs of glycolysis include a living cell, cytoplasmic enzymes, glucose, and energy transfer molecules nicotinamide adenine dinucleotide (NAD+) and adenosine triphosphate (ATP).ADP.
  • Hence ATP, ADP, $NAD^+$, Glucose, cytoplasmic enzymes are required in glycolysis.
  • So, the correct answer is 'ATP, ADP, $NAD^+$, Glucose, cytoplasmic enzymes'.
Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

EMP is also known as

  1. Glycolysis.

  2. Krebs cycle.

  3. ETS.

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

Glycolysis is also known as E.M.P. pathway which stands for Embden - Meyerhof - Parnas Pathway, which was discovered by Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. Glycolysis splits a 6-carbon sugar, glucose, into two molecules of 3-carbon pyruvate in a series of steps, each catalyzed by a particular enzyme. Glycolysis takes place in the cytoplasm (cytosol) of all living cells, not in mitochondria, and does not require the presence of oxygen. Therefore, glycolysis is also known as cytoplasmic respiration. 

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

1 molecule of glucose and 6 molecules of $O _2$ and 38 ADP combined to form $6 H _2O,\, 6 CO _2$ and 

  1. 38 molecules of ATP

  2. 28 ATP

  3. 38 ADP

  4. 28 ADP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During aerobic respiration, one molecule of glucose is oxidized with the help of six oxygen molecules to produce six molecules of carbon dioxide. Six molecules of water are also produced in the process. During aerobic respiration ATP is produced by the processes of substrate level phosphorylation and oxidative phosphorylation. Combined together these processes produce 38 molecules of ATP by phosphorylating 38 molecules of ADP.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Which of the following is incorrect about glycolysis?

  1. Glycolysis converts a single molecule into two molecules of pyruvate.

  2. Glycolysis can produce a net total of 2 ATP for each glucose.

  3. The end product of glycolysis can form ethanol, lactate, or acetyl CoA.
  4. During glycolysis $FADH _{2}$ is produced.

  5. During glycolysis, NADH is produced.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Glycolysis produces NADH, but it does not produce FADH2. FADH2 is produced in the Krebs cycle.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

In animal cells, the first stage of glucose breakdown is

  1. Krebs cycle

  2. Glycolysis

  3. Oxidative phosphorylation

  4. Electron transport chain
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cellular respiration is a complex process that involves multiple pathways. The first step is the glycolysis of glucose which is then followed by Krebs' cycle and ETS in the end. The end products of respiration is CO$ _2$ and H$ _2$O along with release of energy in the form of ATP. Glucose breakdown first starts with glycolysis.

So, the answer is 'Glycolysis'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Glycolysis is conversion of

  1. Glucose to glycogen

  2. Glycogen to glucose

  3. Glucose to pyruvic acid

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

The first step of cellular respiration is the process of glycolysis, a process in which there is breakdown of an organic substance like glucose to pyruvic acid. There is stepwise oxidation of the substrate with the release of energy.

So, the correct answer is 'Glucose to pyruvic acid.'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Glycolysis

  1. Occurs in mitochondria.

  2. Has no connection with ETC.
  3. Reduces 2 molecules of NAD$^+$ per glucose.

  4. Produces no ATP.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In glycolysis, glucose undergoes partial oxidation to form two molecules of pyruvic acid in a multi-step process catalyzed by various enzymes. In which 2 ATP molecules are obtained and NAD$^+$ into 2 molecules NADH when 2 moles of 1,3-diphosphoglyceraldehyde converts into two moles of 1,3 diphosphoglyceric acid.

So the correct option is 'Reduces 2 molecules of NAD+ per glucose.'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

The energy releasing metabolic process in which substrate is oxidised without an external electron acceptor is

  1. Fermentation

  2. Aerobic respiration

  3. Photorespiration

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

Cellular respiration aims at producing energy in the form of ATP and occurs in every living cell. The respiration starts with glycolysis, a stepwise process that oxidises respiratory substrate like glucose. Oxidation is in the form of removal of hydrogen and there is no external electron acceptor present.

So the answer is 'Glycolysis'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Which of the following is formed from phosphorylation?

  1. Fructose 1,6-bisphosphate

  2. Phosphoglyceric acid

  3. PEP

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

Phosphorylation is the addition of a phosphate group to an organic molecule.

During the glycolysis in the 3rd step, Fructose-6-phosphate is converted into Fructose1,6- bisphosphate. Here one ATP is consumed and converted to ADP as the phosphate group gets attached to the fructose. Here the enzyme used is phosphofructokinase.
So, the correct option is 'Fructose 1,6-bisphosphate'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

For bacteria to continue growing rapidly when they are shifted from an environment containing $O _{2}$ to an anaerobic environment, they must

  1. Produce more ATP per mole of glucose during glycolysis

  2. Produce ATP during oxidation of glucose

  3. Increase the rate of glycolysis

  4. Increase the rate of TCA cycle
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For bacteria to continue growing rapidly when they are shifted from an environment containing O2 to an anaerobic environment, they must increase the rate of glycolysis. Although the amount of ATP produced by anaerobic glycolysis (2) is very less as compared to ATP produced by aerobic glycolysis (38), glycolysis under anaerobic condition is very quick process. It generates ATP very quickly. 

Thus, the correct answer is 'Increase the rate of glycolysis.'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

How many molecules of oxygen are used during the glycolysis of one glucose molecule?

  1. 2

  2. 32

  3. 38

  4. Zero

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Glycolysis is the process of partial oxidation of glucose into two molecules of pyruvic acid through the enzyme-mediated reaction series.
  • Here two molecules of ATP are utilized. First during the conversion of Glucose to Glucose-6-phosphate and second during the conversion of Fructose-6-phosphate to Fructose-1,6-biphosphate.
  • 4 molecules of ATP are synthesized during 2 substrate based phosphorylated reaction. 
  • First 2 molecules of ATP released during the conversion of 2 molecules of 1,3 bisphosphoglyceric acid to 2 molecules of 3 phosphoglyceric acids. Next 2 molecules are released during the conversion of 2 molecules of phosphoenolpyruvate to 2 molecules of pyruvic acid. 
  • In splitting of one glucose molecule into two pyruvates only the enzymes present in the cytoplasm are used and no oxygen is required. 
  • It is an anaerobic process.
So, the correct option is D ' zero'.
 

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Choose the correct answers from the alternatives given :
Which of these processes occurs in the cytosol?

  1. Krebs cycle

  2. Glycolysis

  3. Electron transport system

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

The process of cellular respiration occurs into three steps :

  1. Glycolysis
  2. Krebs cycle 
  3. Terminal oxidation
Glycolysis is the basic step of respiration where glucose is broken down into two molecules of pyruvate which occurs in the cytoplasm and does not require oxygen while other processes like Krebs cycle, electron transport system and transition reaction occurs in the mitochondria of the cell.
So, the correct option is ' Glycolysis'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

The inner membrane of mitochondrion is very selective in respect to entering, molecule. Name a molecule that regularly enters in it

  1. Pyruvic acid

  2. Glucose

  3. ATP

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

Cellular respiration occurs firstly in the cytoplasm and then in mitochondria. Glycolysis occurs in the cytoplasm in which glucose breaks into two pyruvates which are transported to mitochondria through an inner mitochondrial membrane which performs the Krebs cycle. This pyruvate regularly enters the mitochondria to start the Krebs cycle and complete cellular respiration.

So, the correct option is ' pyruvic acid'.