Tag: bio-chemistry

Questions Related to bio-chemistry


In aerobic cellular respiration, most of the ATP is synthesized during:

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

  1. Electron transport

  2. Glycolysis

  3. Krebs cycle

  4. Oxidation of pyruvic acid

Show answer
Correct Option: C
Explanation:

Cellular respiration occurs in three steps :

  1. Glycolysis 
  2. Krebs cycle 
  3. Terminal oxidation 
Glycolysis is the breakdown of glucose into two molecules of pyruvate where 2 NADH and 2 ATP molecules are formed which in total is 8 ATP molecules as 1 NADH = 3 ATP, While in Krebs cycle reaction occurs in mitochondria where 10 NADH molecules, 2 FADH, and 4 ATP molecules are formed, in total 38 ATP molecules are formed .
So, the correct option is ' Krebs cycle'.

Choose the correct answers from the alternatives given :
Which one of the following is the energy currency of the cell?

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

  1. AMP

  2. ADP

  3. ATP

  4. NADP

Show answer
Correct Option: C
Explanation:

ATP ( Adenosine triphosphate ) is the energy currency of the cell, it helps in the completion of all the metabolic processes by utilization of its phosphorus molecule. It is generated by mitochondria. One molecule of ATP releases around 30.5 kJ /mol of energy.

So, the correct option is ' ATP'.

Choose the correct answers from the alternatives given :
Of the 36 ATP molecules that are produced during the complete breakdown of glucose, most are due to the action of 

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

  1. substrate-level phosphorylation

  2. electron transport system

  3. chemiosmotic phosphorylation

  4. both (b) and (c)

Show answer
Correct Option: D
Explanation:
  • Substrate level phosphorylation is the part of glycolysis reaction whihc will give the cell 2 molecules of ATP at the end of the reaction.
  • Electron transport system is the transport system that is present in the mitochondrial membrane where it transports the electrons and hydronium ions from NADH and FAD through various complex of the chain.
  • In chemiosmotic phosphorylation the $F _1$-$F _0$ complex is used for the synthesis of one molecule of ATP for every 2 hydronium ion that is transported through the complex from the intermembrane matrix.
  • For each NADH transported through the chain 3 times 2 hydronium ions are released which means every molecule of NADH produces 3 molecules of ATP. For every FADH molecules passed 2 times 2 hydronium are released which means that every molecule of FADH gives 2 ATP molecules.
  • Therefore when per pyruvic acid after going under kerb cycle gives 4 NADH and 1 FADH molecule that gives the cell with  12 ATP and 2 ATP molecules respectively per cycle.
  • Therefore ETS and the chemisomotic phosphorylation give the major contribution in the formation of ATP i.e. 15 ATP per cycle.
  • Therefore the answer option 'both (b) and (c)' is correct.

Choose the correct answers from the alternatives given :
The greatest contributor of electrons to the electron transport system is

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

  1. oxygen

  2. transition reaction

  3. glycolysis

  4. Krebs cycle

Show answer
Correct Option: D
Explanation:
  • Electron transport system is the transport system that is present in the mitochondrial membrane where it transports the electrons and hydronium ions from NADH and FAD through various complex of the chain.
  • In chemiosmotic phosphorylation the $F _1$-$F _0$ complex is used for the synthesis of one molecule of ATP for every 2 hydronium ion that is transported through the complex from the intermembrane matrix.
  • For each NADH transported through the chain 3 times 2 hydronium ions are released which means every molecule of NADH produces 3 molecules of ATP. For every FADH molecules passed 2 times 2 hydronium are released which means that every molecule of FADH gives 2 ATP molecules.
  • Therefore when per pyruvic acid after going under kerb cycle gives 4 NADH and 1 FADH molecule that gives the cell with  12 ATP and 2 ATP molecules respectively per cycle.
  • Therefore it can be said that kerb cycle is the major contributor to the electron that are provides to the ETS for the production of ATP.
  • Therefore option 'Krebs cycle' is the correct answer.
Amount of energy released during hydrolysis of a high energy bond of ATP is
bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. $73 Kcal \,{mol}^{-1}$

  2. $0.73 Kcal \,{mol}^{-1}$

  3. $3.4 Kcal\, {mol}^{-1}$

  4. $7.3 Kcal \,{mol}^{-1}$

Show answer
Correct Option: D
Explanation:
Adenosine triphosphate(ATP) is the energy currency of the cell. It is the most important energy carrier which carries energy in the two terminal phosphate bonds(called as high energy bonds or energy-rich bonds). Equal amounts of usable energy are released per mole of ATP or ADP hydrolysis:
$ATP+{H} _{2}O\rightleftharpoons ADP+Pi+7.3Kcal{\,\,mol}^{-1}$
$ADP+{H} _{2}O\rightleftharpoons AMP+Pi+7.3Kcal{\,\,mol}^{-1}$
So the correct answer is '$7.3 Kcal \,{mol}^{-1}$'.

How many ATP molecules will be generated in a plant system during complete oxidation of $40$ molecules of glucose?

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

  1. $180$

  2. $360$

  3. $1440$

  4. $3040$

Show answer
Correct Option: C
Explanation:

$36 $ ATP molecules are produced during complete oxidation of one molecule of glucose.
So, $40$ molecules of glucose will produce $(36 \times 40) ATP= 1440$ ATP.

So the correct option is C.

Which one of the following equations represents the Aerobic respiration?

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

  1. $6CO _2\,+\,6H _2O\,\rightarrow \,C _6H _{12}O _6\,+\,6O _2$

  2. $C _6H _{10}O _2\,+\,6O _2\,\rightarrow\,6CO _2\,+\,5H _2O\,+\,674Kcal$

  3. $C _6H _{12}O _6\,+\,6O _2\,\rightarrow\,6CO _2\,+\,6H _2O\,+\,674Kcal$

  4. $C _6H _{12}O _2\,+\,6O _2\,\rightarrow\,6H _2CO _3$

Show answer
Correct Option: C

The net yield of ATP, except substrate-level phosphorylation, from Krebs cycle per glucose molecule is

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

  1. $12$

  2. $24$

  3. $22$

  4. $36$

Show answer
Correct Option: C
Explanation:

From one molecule of glucose, 38 ATP molecules can be produced during cellular respiration. Glycolysis produces net 2 ATP molecules by substrate level phosphorylation. Kreb cycle produces 2 ATP molecules by substrate level phosphorylation. About 34 ATP are produced from oxidative Phosphorylation. During Kreb cycle, 6 molecules of NAD$^+$ are reduced to NADH and 2 molecules of FAD are reduced to FADH$ _2$. Now 6 NADH produce 6 x 3 = 18 ATP molecules. Similarly, 2 FADH$ _2$ produce 2 x 2 = 4 ATP molecules. Hence, total 18 + 4 = 22 molecules of ATP are produced per glucose molecule from Kreb cycle except substrate level phosphorylation.

Thus, the correct answer is '22.'

If one triose phosphate completely oxidized inside prokaryotic cell than gain of ATP of energy equal to?

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

  1. $5$ ATP

  2. $4$ ATP

  3. $20$ ATP

  4. $19$ ATP

Show answer
Correct Option: D
Explanation:

Triose phosphate is another name of glyceraldehyde 3- phosphate

Total NADH and ATP are produced in the cycle are as follows as -

 Name of process  Gain of ATP
 Glycolysis: glyceraldehyde 3- phosphate $\rightarrow$pyruvate  1 NADH ( each NADH is equal to 3 ATP) + 1 ATP3ATP+ 1ATP = 4ATP
 Oxidative decarboxylation pyruvate $\rightarrow$acetyl CoA  1 NADH = 3 ATP
 Tricarboxylic acid cycle  3NADH +1 FADH (each FADH is equal to 2ATP) + 1 GTP(equivalent to ATP) =  12 ATP

Total gain of ATP, when one triose phosphate is completely oxidised =  4 ATP =3 ATP =12 ATP $\rightarrow$  19 ATP

So, the correct answer is ' 19 ATP '

Mark the incorrect statement

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

  1. The breaking of c-c bonds of complex organic molecules by oxidation cells leading to the release of a lot of energy is called cellular respiration

  2. Initial stage of cellular respiration takes place in cytoplasm

  3. Incomplete oxidation of pyruvate by stepwise removal of all the hydrogen atoms leaving 3 molecules of CO2

  4. TCA cycle starts with condensation of acetyl group with OAA and water to yield citric acid

Show answer
Correct Option: A
Explanation:

Aerobic respiration is comprised by

1) The complete oxidation of pyruvate by stepwise removal of all hydrogen atoms leaving 3 molecules of CO$ _2$. 
2) The passing of the electrons removed as apart of the hydrogen atoms to molecular O$ _2$with the simultaneous synthesis of ATP.
So, the incorrect statement is ' Incomplete oxidation of pyruvate by stepwise removal of all hydrogen atoms leaving 3 molecules of CO$ _2$'.
rest all are correct statements w.r.t. Respiration.