Tag: carbohydrate metabolism

Questions Related to carbohydrate metabolism

What is ATP?

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

  1. A hormone

  2. A protein

  3. An enzyme which brings about oxidation

  4. A molecule which contains high energy bond

Show answer
Correct Option: D
Explanation:

  • Adenosine triphosphate (ATP) is a nucleotide with three phosphates. The ATP is produced by the addition of phosphorous to nucleoside adenosine.
  • The first phosphate is attached by an ester bond. This bond is a normal covalent bond and not a high energy bond. 
  • The two-terminal phosphates are bonded by high energy acid anhydride bonds. 

Thus one molecule of ATP contains two high energy bonds.

ATP stands for which of the following?

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

  1. Adenosine phosphate

  2. Adenine triphosphate

  3. Adenosine diphosphate

  4. Adenosine triphosphate

Show answer
Correct Option: D
Explanation:

Chemically ATP is a nucleotide. In fact it is a higher order nucleotide because it contains not one but three phosphates. Compounds made up of (pentose) sugar and a nitrogenous base are called nucleosides. If the base is adenine, the nucleoside will be called adenosine. 

If one phosphate is attached to adenosine through an ester bond then the compound becomes a nucleotide and in this case it is called adenylic acid or adenosine monophosphate.
When second phosphorous is attached to the first phosphorous, through an acid anhydride bond, the nucleotide is called adenosine diphosphate. When third phosphorous is attached to the second phosphate through another acid anhydride bond, the nucleotide is called adenosine triphosphate or ATP.

$\sim P$ in ATP represents

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

  1. Two bonds with high energy

  2. Two moles of phosphorus

  3. Three atoms of high energy phosphate

  4. None of the above

Show answer
Correct Option: A
Explanation:
ATP is known as energy currency of the cell and it is a nucleotide formed by the combination of adenine as a nitrogenous base, ribose sugar, and triphosphate. It is found in free cells which breaks to form energy by breaking it's high energy phosphate bonds. The high energy phosphate bonds break to form ADP and AMP. It is a hydrolysis reaction which occurs at extreme pH. It dephosphorylates to provide energy for metabolic function.
ATP has three phosphate out of which one is directly attached to the ribose with phosphate ester bond and it is low energy bond. The bond between two phosphate groups is a phosphoanhydride bond which is considered as high energy bond. So ATP has only two high energy bond phosphoanhydride bond.
So, the correct answer is option A.

Conversion of ATP to ADP releases

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

  1. Energy

  2. Enzyme

  3. Hormone

  4. Electricity

Show answer
Correct Option: A
Explanation:

Adenosine Triphosphate or ATP has stored energy in its bond with the third phosphate group. However when required, ATP loses its third phosphate group to release energy and gets converted back to ADP. The energy released is in the form of chemical energy that the cells can use.

So the answer is 'Energy'.

How many ATPs are required by $C _4$ plants in synthesis of one molecule of glucose

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

  1. 18 ATP

  2. 30 ATP

  3. 12 ATP

  4. None of the above

Show answer
Correct Option: B
Explanation:

Most of the plants that are adapted to dry tropical regions have the $C _{4}$ pathway. e.g. Sugarcane, Maize, Sorghum,etc. These plants are known as $C _{4}$ plants.For the formation of sugars, $C _{4}$ plants undergo $C _{4}$ cycle as well as $C _{3}$ cycle or Calvin cycle. In these plants double fixation of carbon dioxide occurs.

ATP consumed in $C _{4}$ plants:
$C _{4}$ cycle - 2 ATP per $CO _{2}$ fixed
$C _{3}$ cycle - 3 ATP per $CO _{2}$ fixed 
Total - 5 ATP per $CO _{2}$ fixed
Thus, to form one molecule of glucose or to fix 6 $CO _{2}$, 6 X 5 = 30 ATP are consumed.

One mole of glucose on metabolism, liberate how many kilo calories of energy ?

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

  1. 180

  2. 80

  3. 160

  4. 380

Show answer
Correct Option: D
Explanation:

On complete combustion of glucose (1 mole) to CO$ _{2}$ & H$ _{2}$O, approx. 686 kcal of energy is released. When 1 g of glucose respires aerobically by ETS, Glycolysis and  Krebs cycle, around 38 ATP molecules are generated. The terminal group of a mole of ATP has around 10 kcal. Thus, 38 ATP molecules represent a yield of 380 kcal of energy.  

So the correct option is '380'

How many ATP and NADPH molecules are respectively required to make one molecule of glucose through the Calvin cycle?
bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

  1. 3 and 2

  2. 9 and 6

  3. 18 and 12

  4. 12 and 18

Show answer
Correct Option: C
Explanation:

For every $CO _{2}$ molecule entering the Calvin cycle, $3$ molecules of $ATP$ and $2$ molecules of NADPH are required. To make one molecule of glucose, $6$ turns of the cycles are required 

$(6\times 3 ATP =18 ATP$ and $6\times 2 NADPH=12 NADPH)$.

In                            Out   
$6$ $CO _{2}$ $1\,\, glucose$
$18 ATP$ $18 ADP$
$12 NADPH$  $12 NADP$ So, the correct answer is '

18 and 12'.

If two moles of glucose are oxidized in the body through respiration, the number of moles of ATP produced are.

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

  1. 19

  2. 38

  3. 57

  4. 76

Show answer
Correct Option: D
Explanation:
Cellular respiration can be an anaerobic or aerobic respiration, depending on whether or not oxygen is present. Anaerobic respiration makes a total of 2 ATP. Aerobic respiration is much more efficient and can produce up to 38 ATP with a single molecule of glucose.
Anaerobic respiration consists of two steps.
               1. Glycolysis (2 ATP)
               2. Fermentation 
               Total = 2 ATP
Aerobic respiration consists of three steps.
               1. Glycolysis (2 ATP)
               2. Krebs Cycle (2 ATP) 
               3. Electron Transport Chain (34 ATP)
               Total = 38 ATP
If two moles of glucose is oxidized in the body through respiration, the number of moles of ATP produced are 38 x 2 = 76.
So the answer is option D '76'. 

The number of ATP molecules produced during the oxidation of $1$ molecule of glucose is 

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

  1. $12$

  2. $18$

  3. $32$

  4. $38$

Show answer
Correct Option: D
Explanation:
1. Glycolysis: 
 C$ _{6}$H$ _{12}$O$ _{6}$ +  2 ATPs  → 2 Pyruvic Acid + 4 H$ _{2}$ + 4 ATPs
2. Formation of Acetyl CoA:
 2 Pyruvic Acid + 2 CoA → 2 Acetyl CoA + 2 CO$ _{2}$ + 2 H$ _{2}$
3. Krebs Cycle:
 2 Acetyl CoA + 3 O$ _{2}$ → 6 H$ _{2}$ + 4 CO$ _{2}$ + 2 ATPs
4. Electron Transport System:
 12 H$ _{2}$+ 3 O$ _{2}$ → 6 H$ _{2}$O + 34 ATPs
Overall Reaction:
C$ _{6}$H$ _{12}$O$ _{6}$ + 6 O$ _{2}$→ 6 CO$ _{2}$ + 6 H$ _{2}$O + 38 ATPs
So, the correct option is '38'.

At the end of Krebs cycle, but before the electron transport chain, the oxidation of glucose has produced a net gain of -

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

  1. $ 3CO _2 , 5 NADH _2 , 1 FADH _2 , 2 ATP$

  2. $ 6CO _2 , 10 NADH _2 , 2 FADH _2 , 4 ATP$

  3. $ 6CO _2 , 10 NADH _2 , 2FADH _2 , 38 ATP$

  4. None of these

Show answer
Correct Option: B
Explanation:

One molecule of the glucose that enters in the glycolysis produces 2 molecules pyruvate and 2 molecules of NADH$ _{2}$ and 2 ATP.  2 molecules of pyruvate will form 2 molecules of Acetyl Co-A and this will release 2 molecules of CO$ _{2}$ and 2 NADH$ _{2}$. These 2 Acetyl Co-A will enter into Kreb's cycle and will release 4CO$ _{2}$, 6NADH$ _{2}$, 2FADH$ _{2}$ and 2ATP.

so, the total gain before the ETC comes out to be 6 CO$ _{2}$, 10NADH$ _{2}$, 2FADH$ _{2}$ and 4ATP.
Hence, the correct answer is '6CO$ _{2}$, 10NADH$ _{2}$, 2FADH$ _{2}$, 4ATP'.