Tag: carbohydrate metabolism

Questions Related to carbohydrate metabolism

The pentose monophosphate shunt is more advantageous than Krebs cycle as

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. It yields more ATP

  2. Ribose sugar is released, which helps in nucleic acid formation

  3. It releases more oxygen

  4. It utilizes less oxygen

Show answer
Correct Option: B
Explanation:

Pentose phosphate pathway is also known as HMP shunt. This pathway provides an alternative route for carbohydrate breakdown. HMP shunt produces some glycolytic intermediates like glyceraldehyde-3-phosphate and fructose-6-phosphate. These intermediates can directly involve in the glycolysis pathway and then in the Krebs cycle. The cycle provides ribose sugar which can be used for the synthesis of nucleic acids. This pathway is considered as advantageous since the ribose sugar is made available. 

Thus, the correct answer is option B. 

Phosphogluconate shunt occurs in

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Mitochondria

  2. Chloroplasts

  3. Cytoplasm

  4. Both A and B

Show answer
Correct Option: C
Explanation:

The reactions of hexose monophosphate shunt occur exclusively in the cytoplasm and is an additional pathway of glucose metabolism which starts with glucose-6-phosphate. About 10-25% of glucose is metabolised by this pathway. In plants, it occurs both in cytosol and plastids. This pathway involves both oxidative and nonoxidative steps. The oxidative steps generate NADPH and ribose-5-phosphate and then non-oxidative steps convert ribose-5-phosphate back into glucose-6-phosphate which can be further utilized for NADPH generations by means of oxidative steps. 

Thus, the correct answer is option C. 

A respiratory cycle where mainly ${NADPH _2}$ are produced is 

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Calvin cycle

  2. Kreb's cycle

  3. EMP pathway

  4. HMP shunt

Show answer
Correct Option: D
Explanation:

During Calvin cycle, $NADH _2$ are not produced. 
During Krebs cycle, 2 $NADH _2$, 1 $FADH _2$, 1GTP are produced. 
During EMP pathway 2 NADH, 2 ATP are produced. 
During HMP pathway, $NADPH _2$ are produced. So, in respiratory cycle  mainly $NADPH _2$ are produced is HMP pathway. Thus, option D is correct.

Pentose phosphate pathway is a mode of

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Amphibolic pathway

  2. Anabolic pathway

  3. Aerobic respiration

  4. Anaerobic respiration

Show answer
Correct Option: C
Explanation:

Pentose phosphate pathway is an alternative pathway to glycolysis which involves the oxidation of glucose-6-phosphate to 6-phosphogluconic acid which in turn gets converted into pentose phosphates. This pathway involve the direct oxidation of glucose-6-phosphate without entering glycolysis and hence is termed as direct oxidation. 

Thus, the correct answer is option C. 

Which of the following is generated in the oxidative phase of pentose phosphate pathway?

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. NADPH

  2. FADH

  3. GTP

  4. None of the above

Show answer
Correct Option: A
Explanation:

The Pentose Phosphate Pathway is an alternative pathway to glycolysis and TCA cycle. It occurs in both prokaryotes and eukaryotes in their cytoplasm

Glucose is broken down by a series of pathways.
The pathway has 2 phases- Oxidative and Non-oxidative.
In the oxidative stage, there are 2 steps where NADP⁺ gets converted to NADPH.
1. Glucose 6-phosphate converts to 6-phosphogluconolactone
2. 6-phosphogluconate converts to Ribulose 5- phosphate
So, the correct option is 'NADPH'

Pentose phosphate pathway takes place only in the

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Cytoplasm

  2. Mitchondria

  3. Peroxisome

  4. Chloroplast

Show answer
Correct Option: A
Explanation:

The pentose phosphate pathway is a metabolic pathway which is carried out in most of the organisms. This pathway occurs parallel to glycolysis. This pathway produces pentoses from glucose 6-phosphate. The pathway takes place in the cytoplasm in most of the organisms. In the case of plants, there are certain reactions which occur in the plastids.

Thus, the correct answer is option A. 

Pentose phosphate pathway takes place only in the

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Cytoplasm.

  2. Mitochondria.

  3. Peroxisome.

  4. Chloroplast.

Show answer
Correct Option: A
Explanation:
The pentose phosphate pathway is a metabolic pathway which is carried out in most of the organisms. This pathway occurs parallel to glycolysis. This pathway produces pentoses from Glucose 6-phosphate. The pathway takes place in the cytoplasm in most of the organisms. In the case of plants, there are certain reactions which occur in the plastids.
Thus, the correct answer is option A. 

An enzyme used in pentose phosphate pathway is

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. RUBP.

  2. Aldolase.

  3. Pyruvate kinase.

  4. Phosphogluconate dehydrogenase.

Show answer
Correct Option: D
Explanation:

In the pentose phosphate pathway 6-Phosphogluconate dehydrogenase (6PGD) is an enzyme that produces NADPH by converting 6-phosphogluconate to ribulose 5-phosphate. NADPH is used for lipid production. Thus the correct answer is option D.

Consider the following statements.


a. The Pentose Phosphate Pathway supplies Erythrose-$4$-Phosphate which is the starting material the synthesis on lignin.
b. The Pentose Phosphate pathway also occurs in plastids.
c. NADPH is generated by the Pentose phosphate pathway

Which of the statements given are correct?

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. $a$ and $b$ only

  2. $a$ and $c$ only

  3. $b$ and $c$ only

  4. $a, b$ and $c$

Show answer
Correct Option: A

The substrate for pentose phosphate pathway is

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Glucose 6-phosphate.

  2. Glucose 1-phosphate.

  3. Fructose 6-phosphate.

  4. Fructose 1-phosphate.

Show answer
Correct Option: A
Explanation:

Pentose Phosphate Pathway runs parallel to glycolysis and takes place in the cytoplasm. The oxidation steps, utilizing glucose-6-phosphate (G6P) as the substrate, occur at the beginning of the pathway and are the reactions that generate NADPH and also give five carbon compound for glycolysis.

So the correct option is 'Glucose 6-phosphate'.