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

Which one of the following is energy currency of the cell?

  1. Phosphate

  2. ATP

  3. ADP

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

The major energy currency molecule of the cell is ATP. This complex  molecule is critical for all life froms, the simplest to the most complex. It is one of the end products of photophosphorylation, cellular respiration and fermentation and used by enzymes and structural proteins in many cellular processes.

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

Number of ATP molecules formed during complete oxidation of fructose 1, 6-diphosphate is 

  1. 20

  2. 32

  3. 36

  4. 40
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fructose-1, 6-bisphosphate is formed during glycolysis as an intermediate product when glucose-1,6-bisphosphate is converted into fructose-1, 6-bisphosphate and enzme phosphofructokinase is used for this. Fructose generally results in the formation of a higher amount of energy after oxidation and in this case, it is more than glucose.

So, the correct option is '40'

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

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

  1. 2 ATP

  2. 4 ATP

  3. 38 ATP

  4. 40 ATP.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If a cell is undergoing aerobic respiration then it will first undergo glycolysis which is the first breakdown of glucose in the cell and then Krebs cycle.

The net gain of ATP in glycolysis is 8 and the net gain of ATP in Krebs cycle including the substrate phosphorylation and oxidative phosphorylation is 30. So, the total gain of ATP is 38 from one molecule of glucose.
So, the correct option is '38 ATP'

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

Common immediate source of energy in cellular activity is 

  1. DNA

  2. ATP

  3. RNA

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

ATP stands for adenosine triphosphate. The energy released by oxidation of organic molecules is transferred into high energy phosphate bonds of ATP, which can be readily utilised when a cell needs energy. One of the three phosphates of ATP is broken down to release energy. Thus, ATP is the intermediate energy transferring compound. 

So, the correct option is  'ATP'

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

Energy currency (reservoir) of the cells is

  1. AMP

  2. ATP

  3. ENA

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

ATP or adenosine triphosphate is considered to be the energy currency of the cell as it has three high energy phosphate bonds.

When the cell needs energy on of the first bond of the ATP is broken down and energy is used for cellular needs.
In the entire body wherever energy or heat generation takes place it results in the conservation of energy in the form of ATP so that the minimum amount of heat is lost and the body can store ATP for future use.
So, the correct option is 'ATP'

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

Oxidation of a molecule of acetyl CoA produces

  1. 12 ATP

  2. 15 ATP

  3. 6 ATP

  4. 19 ATP.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The acetyl CoA produced from pyruvic acid as a result of link reaction enters Krebs' cycle by forming citric acid from oxaloacetic acid. When 1 molecule of acetyl CoA completes 1 round of Krebs' cycle, it produces 3 NADH+H+, 1 FADH2 and 1 ATP. So after going through ETS, a total of 12 ATP is yielded ( 3*3  + 1*2  + 1 ).

So the answer is '12ATP'.

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

Maximum amount of energy/ATP is liberated on oxidation of

  1. Fats

  2. Proteins

  3. Starch

  4. Vitamins
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Fats are complex molecules composed of fatty acids and glycerol. The body needs fats for growth and energy.
Fats are the slowest source of energy but the most energy-efficient form of food. Each gram of fat supplies the body with about 9 grams of energy. 
The oxidation of fats releases the maximum amount of energy.
So, the correct option is 'Fats'
Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Number of ATP molecules which can be built on complete oxidation of pyruvic acid is

  1. 6

  2. 2

  3. 15

  4. 30
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The breakdown glucose takes place during glycolysis in which there is a net gain of 8 ATP. The pyruvic acid so formed undergoes oxidative decarboxylation and thus forms acetyl CoA. This reaction leads in the formation of 2 NADH₂ molecules. It results in the formation of 6 ATP.

Therefore if the complete oxidation of pyruvic acid takes place when there is a net gain of 15 ATP.
So, the correct option is '15ATP'

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

Out of 36 ATP molecules produced per glucose molecule during respiration

  1. 2 are produced outside glycolysis and 34 during respiratory chain

  2. 2 are produced outside mitochondria and 34 inside mitochondria

  3. 2 during glycolysis and 34 during Krebs cycle

  4. All are formed inside mitochondria
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

2 ATP from glycolysis which takes place in the cytoplasm and other cellular respiration processes takes place in mitochondria which gives 34 ATP.

So, the correct option is '2 are produced outside mitochondria and 34 inside mitochondria.'

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