Tag: cellular respiration

Questions Related to cellular respiration

State whether the following statements are true or false.
Glycolysis and fermentation are thought to be older processes than the electron transport system and the Krebs cycle 

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

The initial processes for energy generation by prokaryotes included anaerobic processes such as Glycolysis and Fermentation. The latter happening of endosymbiosis was the major revolution in bringing up aerobic respiration with the advent of mitochondria within the cells.

Before that, the energy generation was an anaerobic process without using oxygen in Glycolysis and Fermentation.
So, the correct option is 'True'.

State whether the following statements are true or false.
The most efficient pathway for ATP production in animal cells is by glycolysis.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:
  • Glycolysis is the pathway were one molecule of glucose is broken down to 2 molecules of pyruvate by the phosphorylation and dephosphorylation reactions.
  • 2 molecules of ATP are used in phosphorylation reaction of glycolysis. First while conversion of glucose to glucose-6-phosphate and the second one during conversion of fructose to fructose1,6-biphosphate.
  • While 4 ATP molecules are produced in the dephosphorylation reaction. 2 ATP are produced while conversion of  1,3 bisphosphoglyceric acid to 3-phosphoglyceric acid and another 2 ATP during conversion of phosphophenolepyruvate to pyruvic acid.
  • So the net gain of ATP at the end of one glycolysis reaction is 2. SO glycolysis is not a efficient pathway for the production of ATP in animal cells, in turn it is a part of the chain of reaction which take place before aerobic or anaerobic respiration in animal cells.
  • Glycolysis provided the reaction of aerobic and anaerobic respiration with the substrates to carry the reaction further and produce ATPs in mitochondria where the prominent reactions for production of energy in animal cell takes place.
  • Glycolysis takes place in the cytoplasm of the cell and the product of the glycolysis is transported to the mitochondria.
  • Therefore Glycolysis is not the most efficient pathway for ATP production. So the sentence above is FALSE and therefore the option 'False' is correct.

Choose the correct answers from the alternatives given :
Which of the following does not form during glycolysis?

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

  1. NADH

  2. ATP

  3. Pyruvate

  4. $FADH _2$

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Correct Option: D
Explanation:
  • NADH is formed in the glycolysis after the reaction of conversion Glyceradehyde 3 phosphate to 3 phosphoglyeric acid when electrons re released and are accepted by the NAD.
  • ATP is formed  while conversion of 1,3 bisphosphoglyceric acid to phospoglyceric acid and also while conversion of phosphophenol to pyruvic acid.
  • And pyruvate is the end product of the glycolysis.
  • FADH is the product which is formed  during the the kerb cycle while formation of succunic acid to malic acid.
  • Thereofte the correct answer is '$FADH _2$'
During complete metabolism of glucose, the number of ATP formed is
parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

  1. 2

  2. 12

  3. 36

  4. 44

Show answer
Correct Option: C
Explanation:
There is a gain of $2$ ATP molecules during glycolysis and $2$ ATP(GTP) molecules during double Krebs cycle. A total of $10$ ${NADH} _{2}$ molecules are formed in aerobic respiration. Thus, the net gain from complete oxidation of a molecule of glucose in muscle and nerve cells is 36 ATP molecules ($10$ ${NADH} _{2}=30 ATP, 2{FADH} _{2}=4 ATP$, four formed by substrate-level phosphorylation in glycolysis and Krebs' cycle and two consumed in transport of the ${NADH} _{2}$ molecules into mitochondria). In aerobic prokaryotes, heart, liver and kidneys, $38$ ATP molecules are produced per glucose molecule oxidised. passage of ATP molecules from inside of mitochondria to the cytoplasm is through facilitated diffusion.
Thus, there is a net gain of $36$ or $38$ ATP molecules depending upon the type of aerobic respiration.
[Note: $1{NADH} _{2}=3ATP$ and $1{FADH} _{2}=2ATP$].
So the correct answer is '36'.
Which of the following statements regarding metabolic pathways is incorrect?
parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

  1. Many of the steps of glycolysis can run in reverse

  2. Starch, sucrose or glycogen must be hydrolysed before it can enter the glycolysis.

  3. After fats are digested, glycerol enters glycolysis by forming DHAP.

  4. After fat digestion, fatty acids can no longer participate in cellular respiration.

Show answer
Correct Option: D
Explanation:

After fats are digested into fatty acids and glycerol, the following products can take place in cellular respiration.

So, the correct option is 'After fat digestion, fatty acids can no longer participate in cellular respiration.'.

The balance sheet for ATP production in glycolysis has been given below. Select the option which correctly fills up the blanks for P,Q,R and S. ['X' stands for 'nil'].

Steps ATP Utilisation ATP Production
1. $Glucose\rightarrow Glucose-6-phosphate$ P X
2. $Fructose-6-phosphate\rightarrow Fructose-1, 6-bisphosphate$ 1 Q
3. $1,3-bisphosphoglyceric acid\rightarrow 3-Phospho-glyceric acid$ X R
4. $2-Phosphoenol pyruvic acid\rightarrow Pyruvic acid$ S 2
parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

  1. P-1; Q-X; R-X; S-2

  2. P-1; Q-X; R-2; S-X

  3. P-2; Q-1; R-X; S-1

  4. P-X; Q-1; R-2; S-X

Show answer
Correct Option: B
Explanation:
During glycolysis, the conversion of glucose into glucose-6-phosphate requires the utilization of one ATP molecule and no ATP molecules are produced. Similarly, there is no production of ATP molecules during the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate and only one ATP molecule is utilized. Also, during the conversion of 1,3−bisphosphoglycericacid to 3−Phospho−glycericacid and that of 2−Phosphoenolpyruvicacid to pyruvic acid, tow molecules each of ATP as utilized and no ATP is produced.

So, the correct answer is 'P-1; Q-X; R-2; S-X'.
Which of the following conversions involve ATP synthesis during glycolysis?
parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

  1. Glucose$\rightarrow$Glucose-6-phosphate

  2. Fructose-6-phosphate$\rightarrow$Fructose-1,6-biphosphate

  3. 1,3-bisphosphoglyceric acid (BPGA) $\rightarrow$ 3-phosphoglyceric acid (PGA)

  4. All of these

Show answer
Correct Option: C
Explanation:

In the energy conserving phase of glycolysis, the conversion of BPGA to PGA is catalyzed by phosphoglycerate kinase. The phosphate on carbon 1 is transferred to a molecule of ADP, yielding ATP and 3-phosphoglycerate. This type of ATP synthesis, traditionally referred to as substrate-level phosphorylation, involves the direct transfer of a phosphate group from a substrate molecule to ADP, to form ATP.
$1,3-bisphosphoglycerate+ADP\overset{Phosphoglycerate kinase}{\underset{{Mg}^{2+}}{\rightleftharpoons}}3-phosphoglycerate+ATP$

How much energy is gained directly during glycolysis from one molecule of glucose?

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

  1. 34 kJ

  2. 72 kJ

  3. 68 kJ

  4. 50 kJ

Show answer
Correct Option: C
Explanation:

Glycolysis produces 2 ATP, 2 NADH,2 pyruvate molecules. It is the aerobic catabolic breakdown of glucose, which produces energy of 68KJ in form of ATP, NADH, and pyruvate, which itself enters a citric acid cycle to produce more energy.

So, the correct option is '68KJ'.

The enzymatic machinery to partially oxidise glucose into pyruvic acid without the help of oxygen.

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

  1. Present in prokaryotic as well as eukaryotic organisms

  2. Occurs in mitochondrial matrix of eukaryotes

  3. Produces four ATP as net gain

  4. More than one option is correct

Show answer
Correct Option: A
Explanation:
The enzymatic machinery to partially oxidise glucose into pyruvic acid without the help of oxygen.
 Ans is A
Present in prokaryotic as well as eukaryotic organisms both. 
In eukaryotic  cell like muscle and RBC and many of the prokaryotic cell use this process. 

The major reason that glycolysis is not as energy productive as respiration is that?

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

  1. $NAD^+$ is regenerated by alcohol or lactate production, without the high-energy electrons passing through the electron transport chain

  2. It is the pathway common to fermentation and respiration

  3. It does not take place in a specialized membrane-bound organelle

  4. Pyruvate is more reduced than $CO _2$; it still contains much of the energy from glucose

Show answer
Correct Option: B
Explanation:

Glycolysis, part of cellular respiration, is a series of reactions that constitute the first phase of most carbohydrate catabolism. Catabolism means the breaking down of larger molecules into smaller ones. The word glycolysis is derived from two Greek words and means the breakdown of something sweet. Glycolysis breaks down glucose and forms pyruvate with the production of two molecules of ATP. The pyruvate end product of glycolysis can be used in either anaerobic respiration if no oxygen is available or in aerobic respiration via the TCA cycle which yields much more usable energy for the cell.  When oxygen is present, NADH can pass its electrons into the electron transport chain, regenerating NAD$^+$ for use in glycolysis. When oxygen is absent, cells may use other, simpler pathways to regenerate NAD$^+$ these pathways, NADH donates its electrons to an acceptor molecule in a reaction that doesn’t make ATP but does regenerate NAD$^+$ so glycolysis can continue. This process is called fermentation.

So the correct option is 'It is the pathway common to fermentation and respiration'.