Tag: bio-chemistry

Quizzes (82) Questions (1918)

Questions Related to bio-chemistry

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Oxidative phosphorylation refers to

  1. Anaerobic production of ATP

  2. The citric acid cycle production of ATP

  3. Production of ATP by chemiosmosis

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

Oxidative phosphorylation is the process where ATP is formed as a result of the transfer of electrons from NADH or FADH2 to O2 by a series of electron carriers, coupled with chemiosmosis.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP synthesis in cell requires

  1. $H^+$ gradient across the membrane
  2. $K^+$ gradient across the membrane
  3. $PO^{3-} _4$ gradient across the membrane
  4. $Ca^{2+}$ gradient across the membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A) A ${ H }^{ + }$ gradient or proton pump is developed in the lumen of the thylakoid which helps in ATP synthesis.
B) ${ K }^{ + }$ does not play a role in ATP synthesis.
C) ${ PO } _{ 4 }^{ 3- }$ does not play a role in ATP synthesis.
D) ${ Ca }^{ 2+ }$ is involved in the photolysis of water.
So the correct answer is '${ H }^{ + }$ gradient across the membrane'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

The chemiosmotic coupling hypothesis of oxidative phospohorylation proposes that adenosine triphosphate is formed because

  1. A Proton gradient forms across the inner membrane

  2. There is a change in the permeability of the inner mitochondria membrane toward adenosine diphosphate

  3. High energy bonds are formed in mitochondrial proteins

  4. ADP is pumped out of the matrix into the intermembrane space
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The chemiosmotic hypothesis states that the energy stored in a proton gradient across the inner mitochondrial membrane drives the synthesis of ATP by ATP synthase.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmotic mechanism of ATP synthesis was proposed by 

  1. Warburg

  2. Dickens

  3. Krebs

  4. P. Mitchell
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis. Peter D. Mitchell proposed the chemisomotic hypothesis in 1961. The theory suggests essentially that most ATP synthesis in respiring cells  comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of $NADH _2$ and $FADH _2$ formed from the breaking down of energy-rich molecules such as glucose.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on

  1. Membrane potential

  2. Accumulation of K ions

  3. Proton gradient

  4. Accumulation of Na ions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The chemiosmotic theory, proposed by Peter Mitchell, explains that ATP synthesis in both chloroplasts and mitochondria is driven by the electrochemical gradient of protons across the membrane.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

With reference to photosynthesis, what is the $CF _0$ - $CF _1$ complex?

  1. ATP synthetase

  2. Ferredoxin-NADP reductase
  3. Cytochrome $b6$/f complex

  4. RuBP carboxylase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The CF0-CF1 complex is the ATP synthase enzyme found in the thylakoid membrane of chloroplasts, responsible for synthesizing ATP during the light reactions.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP is known as energy currency of a cell. ATP is synthesized from ADP and Pi. The reaction is catalyzed by an enzyme called as ATP synthase. When the enzyme and substrate (ADP) are distant inside the cell, the reaction cannot take place spontaneously. Which of the following statements best explains the cause for the ATP synthase and ADP to interact?

  1. Electronegativity of ADP attracts ATP synthase

  2. ADP will be actively pumped to ATP synthase

  3. Random movements will bring ADP to ATP synthase

  4. ADP and ATP synthase always remain bound to oxysomes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Inside a living cell, molecules are in constant thermal motion, leading to random collisions. These random movements eventually bring the enzyme ATP synthase and its substrate ADP into contact so that catalysis can occur.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

How many ATP molecules could maximally be generated from one molecule of glucose, if the complete oxidation of one mole of glucose to $CO _2$ and $H _2O$ yields $686$kcal and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is $12$kcal?

  1. $1$
  2. $2$
  3. $30$
  4. $57.1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Calvin cycle has three stages.
$1$. Reduction during which carbohydrate is formed at the expense of photochemically made ATP and NaDPH.
$2$. Regeneration during which carbon dioxide acceptor $1, 5$-RuBP is formed.
$3$. Carboxylation during which $CO _2$ combines with $1, 5-$RuBP.
Identify the correct sequence.

  1. $3, 1, 2$
  2. $3, 2, 1$
  3. $1, 2, 3$
  4. $2, 1, 3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Calvin cycle consists of: 1. Carboxylation (CO2 + RuBP), 2. Reduction (using ATP/NADPH to form sugar), and 3. Regeneration (reforming RuBP). The sequence is 3, 1, 2.