Tag: bio-chemistry

Questions Related to bio-chemistry

Which of the following cellular metabolic processes can occur both in the presence or absence of ${O} _{2}$?
hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Glycolysis

  2. Fermentation

  3. TCA cycle

  4. Electron transport coupled with chemiosmosis

Show answer
Correct Option: A
Explanation:

Glycolysis is an oxidative process in which one molecule of glucose is partially oxidised into two molecules of pyruvate in a series of enzyme catalysed reactions. Glycolysis, the major pathway for glucose metabolism, occurs in the cytosol of cells. It is a unique pathway that occurs aerobically as well as anaerobically and does not involve molecular oxygen.

Which one requires oxygen?

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Fermentation.

  2. EMP pathway.

  3. Pentose phosphate pathway.

  4. None of the above.

Show answer
Correct Option: D
Explanation:

All the processes occur in the absence of oxygen i.e., anaerobic condition. 

So the correct option is 'None of the Fermentation or EMP pathway or Pentose phosphate pathway.'

Which is not pentose?

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Erythrose

  2. Ribose

  3. Xylose

  4. Arabinose

Show answer
Correct Option: A
Explanation:

The pentose sugars ribose and deoxyribose are part of the nucleotides that make up the crucial nucleic acids like DNA and RNA. So the correct option is 'Erythrose'.

Which one of the following hormone never reaches to cytoplasm?

hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. Estrogen

  2. FSH

  3. Progesterone

  4. Testosterone

Show answer
Correct Option: B
Explanation:

FSH is a proteinaceous hormone. It does not enter its target cells, thus, it never reaches to cytoplasm. Instead, it binds to the receptor present on the cell membrane and activates a membrane bound enzyme that causes conversion of ATP to cAMP. This then alters the activities of enzyme in the cytoplasm.

Last ${e}^{-}$ acceptor during ETS is 
hmp shunt alternative to glycolysis carbohydrate metabolism respiration bio-chemistry

  1. ${O} _{2}$

  2. cyt $a$

  3. cyt ${a} _{2}$

  4. cyt ${a} _{3}$

Show answer
Correct Option: A
Explanation:

In electron transport chain, there are 7 electron acceptors, which are as follows $Co-Q\rightarrow Cyt\,\, b\rightarrow Cyt \,\,{c} _{1} \rightarrow Cyt \,\,c\rightarrow Cyt \,\,a\rightarrow Cyt \,\,{a} _{3}\rightarrow{O} _{2}$. Oxygen is the ultimate electron acceptor. These electron acceptors are present in a specific sequence along inner mitochondrial membrane.

Which is true about the end products of glycolysis?
bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

  1. $2\,pyruvic \,acid+2ATP+{2NADH} _{2}$

  2. $2\,pyruvic \,acid+{2NADH} _{2}$

  3. $1\,pyruvic \,acid+2ATP+{2NADH} _{2}$

  4. $2\,pyruvic \,acid+1ATP+{1NADH} _{2}$

Show answer
Correct Option: A
Explanation:
In glycolysis, two molecules of ATP are consumed during two phosphorylation reactions to form fructose 1, 6-biphosphate. In return, four molecules of ATP are produced by substrate-level phosphorylation (conversion of 1, 3-biphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate to pyruvate). Two molecules of ${NADH} _{2}$ are formed at the time of oxidation of glyceraldehyde 3-phosphate to 1, 3-biphosphoglycerate. The net reaction of glycolysis is as follows:

$Glucose+{2NAD}^{+}+2ADP+{2H} _{3}{PO} _{4}\rightarrow2Pyruvate+2NADH+{2H}^{+}+2ATP$

Each NADH is equivalent to 3 ATP, so the net gain in glycolysis is 8 ATP.

So the correct answer is '$2\,pyruvic \,acid+2ATP+{2NADH} _{2}$'.

In glycolysis, glucose molecule is converted into which substance?

bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

  1. Lactic acid

  2. Ethanol

  3. Pyruvate

  4. Amino acid

Show answer
Correct Option: C
Explanation:

The process by which the glucose (6C compound) is split into two molecules of pyruvic acid (3C compound) is called glycolysis or EMP pathway. It occurs in the cytoplasm. In glycolysis, 4ATP and 2NADH$ _2$ molecules are formed and 2ATP molecules are consumed in hexose phase

So, the correct answer is 'Pyruvate'

For the start of respiration, a living cell requires

bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

  1. Glucose

  2. Glucose + $O _2$

  3. $O _2$

  4. Glucose + ATP

Show answer
Correct Option: D
Explanation:

The mechanism of respiration is initiated by breaking down glucose to pyruvic acid without the help of oxygen. The initial process occurs in the cytosol of cells which requires glucose as well as ATP molecules which provide energy for the process to start. This initial process is known as glycolysis and it takes place in 10 steps in which total 4 ATP molecules are produced and 2 ATP molecules are consumed. Thus, these are the net production of 2 ATP molecules. 

Thus, the correct answer is option D. 

How many ATP are produced in mitochondria on complete oxidation of glucose?

bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

  1. $24$

  2. $30$

  3. $34$

  4. $38$

Show answer
Correct Option: A
Explanation:
Name of process   Site  Total ATP formation
 Glycolysis  Cytoplasm  2NADH(i.e. 6ATP)+ 2ATP = 8ATP 
 Conversion of pyruvate to acetyl CoA  Cytoplasm  2NADH = 6ATP
 Kreb's cycle  Mitochondria  6NADH + 2 FADH + 2GTP= 18ATP +4ATP + 2ATP  = 24 ATP

 1 NADH = 3 ATP, 1 FADH = 2 ATP

So, the correct answer is '$24$'

When one molecule of sucrose is subjected to phosphorylation how many ATPs are consumed?

bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

  1. 2

  2. 6

  3. 3

  4. 4

Show answer
Correct Option: A
Explanation:

During the conversion of fructose-1,6-bis-phosphate to lactate, the pathway generates a total of four molecules of ATP, resulting in a net yield of two ATP per glucose consumed.

correct answer is A.