Tag: chemiosmotic hypothesis

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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.

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

The idea that pH gradients could provide energy for ATP formation in chloroplasts and mitochondria was first proposed by ____________.

  1. Bassham

  2. Hill

  3. Mitchell

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

Peter Mitchell proposed the chemiosmotic hypothesis, which states that proton gradients across thylakoid and inner mitochondrial membranes provide the driving force for ATP synthesis.

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

Which of the following step of photosynthesis is not directey involve in ATP synthesis or consumption?

  1. Corboxylation of dark Rection

  2. Reduction of dark reaction

  3. Cyclic photo phosphorylation of light reaction

  4. Regeneration of dark reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carboxylation of the dark reaction (Calvin cycle) does not directly involve ATP synthesis or consumption. The enzyme RuBisCO catalyzes CO2 fixation with RuBP without ATP. Both reduction and regeneration phases consume ATP, and cyclic photophosphorylation produces ATP.

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

Direct gain of ATP from one mole of glucose during glycolysis or EMP pathaway ____________.

  1. 2 ATP

  2. 6 ATP

  3. 36 ATP

  4. 38 ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis (EMP pathway) produces a net gain of 2 ATP molecules per glucose molecule through substrate-level phosphorylation. While 4 ATP are grossly produced, 2 ATP are consumed in the energy investment phase, resulting in a net yield of 2 ATP.

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

Photosynthetic oxygen producing cells differ from non-oxygen producing cells in that the former.

  1. Produce one ATP whereas the latter produce two
  2. Produce no NADPI-$1$ whereas the latter do

  3. Reduce ferredoxin whereas the latter do not

  4. Contain and use both photo systems I and II
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxygen-producing photosynthesis (oxygenic photosynthesis, found in cyanobacteria, algae, and plants) relies on a non-cyclic electron transport chain that requires both Photosystem I and Photosystem II working in series. Non-oxygen producing organisms (like some bacteria) typically use anoxygenic photosynthesis with only a single photosystem.