Tag: bio-chemistry

Quizzes (82) Questions (1918)

Questions Related to bio-chemistry

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

In oxidative phosphorylation, oxidation and phosphorylation take place simultaneously and forms:

  1. NADP

  2. DPN

  3. Pyruvic acid

  4. ATP

  5. Both B and D
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Oxidative phosphorylation refers to synthesis of ATP by ADP and Pi driven by energy released from oxidation of reducing powers NADH and FADH2 by transfer of their electrons through electron trasnport chain to oxygen. Electron trasnport chain is present in inner mitochondrial membrane and passes the electrons down a series of carriers and pump protons into the intermembrane space. Oxygen serves as final electron acceptor in oxidation of NADH and FADH2 and the resulting proton gradient serves as energy source for the enzyme ATP synthase to synthesize ATP. So final products of oxidative phosphorylation are ATP, NAD and FAD. DPN (diphosphopyridine nucleotide), also called as NAD. Correct answers are D and B. NADP is coenzyme of photosynthetic light reactions. Puruvic acid is product of glycolysis. 

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Oxidative phosphorylation is the formation of 

  1. NADPH$ _{2}$ in respiration

  2. ATP in respiration
  3. NADPH$ _{2}$ in photosynthesis

  4. ATP in photosynthesis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxidative phosphorylation is the metabolic pathway in which the mitochondria in cells use their structure, enzymes and energy released by the oxidation of nutrients to reform ATP in respiration.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Biological phosphorylation is the formation of 

  1. $N _{2}$
  2. $CO _{2}$
  3. $ATP$
  4. $SO _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Biological phosphorylation is of two types- protein phosphorylation and oxidative phosphorylation. In protein phosphorylation, the proteins get attached with a phosphate group. Oxidative phosphorylation is the metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

$FAD^+$ is reduced during conversion of 

  1. Citric acid to isocitric acid
  2. Isocitric acid to $ \alpha - $ ketoglutaric acid
  3. $ \alpha - $ ketoglutaric acid to succinyl CoA

  4. Succinic acid to fumaric acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During one of the steps of Krebs cycle, succinic acid is converted to fumaric acid. The reaction is accompanied by coenzyme FAD (flavin adenine nucleotide). This oxidation reaction liberates less free energy as compared to other oxidation reactions. FAD$^+$ is the hydrogen acceptor in this reaction as there is very less free-energy change. In this reaction, succinic acid is oxidized to fumaric acid. At the same time, FAD$^+$ is reduced to FADH$ _2$. 

Thus, the correct answer is option D.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

During aerobic respiration, the substrate level phosphorylation takes place in.

  1. Cytoplasm only

  2. Mitochondria only

  3. Cytoplasm and mitochondria

  4. Cytoplasm and Golgi complex
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Substrate-level phosphorylation occurs in the cytoplasm during glycolysis (e.g., conversion of 1,3-bisphosphoglycerate and phosphoenolpyruvate) and in the mitochondria during the Krebs cycle (e.g., succinyl-CoA to succinic acid). Therefore, it takes place in both cytoplasm and mitochondria.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis


Within the mitochondrion, the proton gradient develops across the

  1. Outer membrane

  2. Inner membrane

  3. Intermembrane space

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

The electrons from NADH AND FADH$ _2$ flows through the inner mitochondrial membrane, thus forming a proton gradient i.e; building an H+ pump which flows through the membrane enzyme complex. An enzyme responsible for this process and energy generation is ATP synthase.

So, the correct option is ' inner membrane'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Choose the correct answers from the alternatives given :
Chemiosmotic phosphorylation is dependent upon

  1. the ability of ADP? to join with P even in the absence of a supply of energy
  2. the establishment of an electrochemical hydrogen ion $(H^+)$ gradient

  3. an outside supply of phosphate and other chemicals

  4. the diffusion of waste across a differentially permeable membrane
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Chemiosmotic phosphorylation is the process where ATP is formed by the ATP synthase complex which is present in the inner membrane of the mitochondria.
  • The formation of ATP by this complex takes place when 2 hydronium ions are transported across the complex from the inter membrane space down its concentration gradient.
  • Thus the formation of ATP in this process takes place due to the concentration gradient that is formed by the presence of hydronium ion that is formed by the ETS Chain when the electron along with hydronium ions are transported from the NADH and FADH.
  • Therefore the answer 'the establishment of an electrochemical hydrogen ion (H+) gradient' is correct.










Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Choose the correct answers from the alternatives given :
Substrate-level phosphorylation takes place in 

  1. Krebs cycle and the transition reaction

  2. glycolysis and the electron transport system

  3. electron transport system and the transition reaction

  4. glycolysis and the Krebs cycle
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Substrate level phosphorylation is the reaction where ATP is formed by the phosphate molecule that is taken from the substrate in the reaction.
  • In glycolysis during the conversion of 1,3 bisphosphoglyceric acid to 3 phosphoglyceric acid and coversion of phosphophenol to pyruvic acid; one molecule of ATP is formed during each reaction.
  • In kerb cycle during the formation of succinic acid from succinyl CoA GTP is formed which is a substrate level phosphorylation, afterwards this GTP is converted to ATP in a coupled reaction.
  • No substrate level phosphorylation takes place in oxidative phosphorylation or ETS
  • Therefore the answer 'glycolysis and the Krebs cycle' is correct.
Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Choose the correct answers from the alternatives given :
Which of the following occurs only in aerobic conditions?

  1. Glycolysis

  2. Lactate respiration

  3. Oxidative phosphorylation

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

  • Glycolysis is the first part of the reaction that provides substrate for the further reaction of aerobic and anaerobic reaction. IT takes place in cytoplasm and does not require any oxygen.
  • LActate respiration and fermentation both are the reaction that take place in the cells or the tissues which respiration in anaerobic conditions or when there is not enough oxygen.
  • Oxidative phosphorylation is the process that takes place in the in the inner mitochondrial membrane where the electrons and hydronium ions are transported through a series of complexs and at the end the electrons and hydronium are accepted by the oxygen and water is formed, this is the process in the aerobic respiration where the oxygen is used and it cannot be completed with it.
  • Therefore the answer option 'Oxidative phosphorylation' is correct.