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 bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Maximum energy becomes available per mole of glucose when it is metabolised through

  1. Glycolysis in skeletal muscle of a sprinter.

  2. Fermentation into ethanol by yeast.

  3. Fermentation into methanol by enteric bacteria.

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

Cells performing aerobic respiration synthesize much more ATP, but not as part of glycolysis. 

So the correct option is 'Aerobic respiration'.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

In aerobic respiration one glucose produces

  1. $8 NADH + 2 FADH _2 + 2 ATP$
  2. $12 NADH + 2 FADH _2 + 38 ATP$
  3. $12 NADH + 30 ATP + H _2O$
  4. $10 NADH + 2 FADH _2 + 2 ATP + 2 GTP$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
| Process |  Site |  Energy Release | | --- | --- | --- | |  Glycolysis(breakdown of glucose into pyruvic acid) |  In cytoplasm |  2 ATP 2 NADH | | Decarboxylation(conversion of pyruvic acid into Acetyl co enzyme) | mitochondria |  2 ATP | |  Citric Acid Cycle(Oxidation of acetyl co enzyme)(when the cycle runs twice) | mitochondria |  8 NADH 2 FADH 2 GTP   | |  Total |   |  10+28=38 |
So the correct option is  $ 10NADH$+ $2 FADH _2$ +$2ATP$+ $2GTP$
Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Oxidation of one molecule of glucose in aerobic respiration produces

  1. 2 ATP

  2. 30 ATP

  3. 36 ATP

  4. 38 ATP
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
 Product  Molecule  ATP
 Glycolysis  2 ATP2NADH  8ATP
 Krebs cycle NADH  3 (in two cycle)  18 ATP
 FADH$ _2$  2 (in two cycle)  4 ATP
 GTP  2 (in two cycle)  2ATP
 Oxidative decarboxylation  2 NADH (in two cycle)  6ATP
 Total    38
Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Number of ATP molecules produced from 1 glucose molecule in aerobic respiration

  1. 38

  2. 32

  3. 30

  4. 28
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
 Product  Molecule  ATP
 Glycolysis  2 ATP2NADH  8ATP
 Krebs cycle NADH  3 (in two cycle)  18 ATP
 FADH$ _2$  4 (in two cycle)  4 ATP
 GTP  2 (in two cycle)  2ATP
 Oxidative decarboxylation  2 NADH (in two cycle)  6ATP
 Total    38
Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

The energy consumed during the conversion of ADP into ATP is 

  1. 73000 cal/mole

  2. 686000 cal/mole

  3. 8000 cal/mole

  4. 7300 cal/mole
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Adenosine-5'-triphosphate (ATP) is comprised of an adenine ring, a ribose sugar, and three phosphate groups. ATP is often used for energy transfer in the cell. ATP synthase produces ATP from ADP or AMP + Pi. The energy consumed during the conversion of ADP into ATP is 7300 cal/mole.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Net gain of ATP in prokaryotes from a molecule of glucose when oxidized is

  1. 40

  2. 38

  3. 36

  4. 34
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A total 38 ATP molecules (2 ATP molecules from glycolysis, 2 from Kreb's cycle and 34 from electron transport system) are produced per molecule of glucose oxidised in aerobic prokaryotes. Whereas, the net gain in most of the eukaryotes is 36 ATP molecules (as 2 ATP molecules are consumed intransporting $NADH _2$ into mitochondria). 

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

 Energy produced during aerobic respiration of glucose 

  1. 637 kcal

  2. 640 kcal

  3. 686 kcal

  4. 693 kcal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Aerobic respiration takes place through a series of reactions such as Glycolysis, Oxidative decarboxylation of pyruvates, Citric acid cycle and Oxidative phosphorylation. Being efficient in extracting chemical energy, the total free energy produced during the process is 686 kcal. Thus, the correct answer is option C.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

The net gain of energy from one molecule of glucose during aerobic respiration is 

  1. 2 ATP

  2. 36 ATP

  3. 38 ATP

  4. 15 ATP
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

38 molecules can be made per oxidised glucose molecule during cellular respiration. It is possible by the yield of ATP molecules from Krebs cycle, glycolysis and electron transport system. 

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

The net gain of ATP from one molecule of glucose in aerobic respiration is

  1. 18 ATP

  2. 38 ATP

  3. 60 ATP

  4. 80 ATP
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If the food substances in living cells are oxidized in presence of oxygen, it is called aerobic respiration. It is the step-wise complete breakdown of the respiratory substrates like glucose into simpler molecules like $CO _2$ and water with the release of ATP. It is mostly seen in eukaryotic type of organisms. Each glucose molecule on complete oxidation gives 38 ATP molecules. 

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

How many PGAL are produced by glycolysis of 3 molecules of glucose? How many ATP are released by respiration of these PGAL till formation of $O _2$ and $H _2O$?

  1. 4 PGAL-80 ATP

  2. 6 PGAL-160 ATP

  3. 4 PGAL40 ATP

  4. 6 PGAL-120 ATP
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Glycolysis of one molecule of glucose produces 2 PGAL, thus of three molecules will produce 6 PGAL.
Respiration of one molecule of glucose or 2 PGAL produces 38 ATP molecules, thus, of 6 PGAL will produce 114 ATP molecules. Out of the given options 120 ATP is the nearest correct answer. Thus the correct answer is option D.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Which of the following is not an electron transferring molecule?

  1. ATP
  2. NAD$^{+}$

  3. Fe-S protein

  4. Co-enzyme Q
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Adenosine triphosphate is a nucleoside triphosphate used in cells as a coenzyme. It is often called the molecular unit of currency of intracellular energy transfer. ATP transports chemical energy within cells for metabolism. It is one of the end products of photophosphorylation, cellular respiration and fermentation and used by enzymes and structural proteins in many cellular processes, including biosynthetic reactions, motility and cell division. One molecule of ATP contains three phosphate groups.