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

Light energy is not used directly or indirectly in which of the following option?

  1. Splitting of ${ H } _{ 2 }O$

  2. To develop proton gradient during photophosphorylation
  3. ${ CO } _{ 2 }$ reduction in dark reaction

  4. To develop proton gradient during oxidative photophosphorylation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

NADH and FADH$ _{2}$ transfer their electrons to molecules near the beginning of the transport chain. As electrons are passed down the chain, they move from a higher to a lower energy level, releasing energy. Some of the energy is used to pump H$^{+}$ ions, moving them out of the matrix and into the intermembrane space. The energy released in these reactions is captured as a proton gradient, which is then used to make ATP in a process called chemiosmosis. Together, the electron transport chain and chemiosmosis make up oxidative phosphorylation. 

So, the correct option is 'To develop proton gradient during oxidative photophosphorylation'.

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

Which theory explains ATP synthesis in chloroplasts and mitochondria?

  1. Lipman and Lohmann theory.

  2. Lock and Key theory of Fischer.

  3. Induced fit theory of Koshland.

  4. Chemiosmotic theory of Mitchell.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The chemiosmotic theory explains how ATP is generated from mitochondria by electron transport chain. The chemiosmotic theory was developed by the British biochemist, Peter Mitchell, to explain the mechanism of oxidative phosphorylation in mitochondria (and photophosphorylation in chloroplasts). 

So the correct option is 'Chemiosmotic theory of Mitchell.'

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

State whether the following statements are true or false .
ATP is a protein that supplies energy to the cell.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

ATP is not a protein, it is a nucleotide. Proteins are made up of amino acids. While ATP is a nucleotide consisting of an adenine base attached to a ribose sugar, which is attached to three phosphate groups. 

So, the correct option is 'False'.

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

Read the following statements and find out the incorrect statement.

  1. Glucose is prepared at the source by photosynthesis which is converted to sucrose

  2. Loading at the source produces a hypotonic condition in phloem

  3. Loading of the phleom sets up a water potential gradient that facilitates the mass movement in the water

  4. Phloem tissue is composed of sieve tube cells, which form long columns with holes in their end walls called sieve plates
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Loading of sucrose into the phloem at the source creates a hypertonic condition (high solute concentration) rather than hypotonic, drawing water in by osmosis to generate high pressure. Therefore, statement B is factually incorrect and represents the correct choice.

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

Continued evolution of $O _2$ in suspension of an isolated chloroplast in light in the presence of ferric salt, violate dyes, etc. is called

  1. Oxygenation

  2. Blackmans reaction

  3. Hills reaction

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

The Hill reaction is defined as the photoreduction of an electron acceptor by the hydrogens of water, with the evolution of oxygen. In vivo, or in the organism the final electron acceptor is NADP+. We can measure the rate of the Hill reaction in isolated chloroplasts. first demonstrated by Robert Hill in 1939, in which illuminated chloroplasts evolve oxygen when incubated in the presence of an artificial electron acceptor (e.g. Ferricyanide). The reaction is a property of photosystem II. 

So, the correct option is, 'Hills reaction'.

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

State whether the following statements are true or false .
The energy currency of a cell is adenosine triphosphate (ATP). ATP is chemically a lipoprotein.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
lipoprotein is a biomolecule that is a combination of fat and protein. While ATP is a nucleotide consisting of an adenine base attached to a ribose sugar, which is attached to three phosphate groups. 
So, the correct option is 'False'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Which of the following cell organelles in concerned with photophosphorylation?

  1. Mitochondria

  2. Plastochondria

  3. Chloroplast

  4. More than one option is concerned
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The synthesis of ATP is called phosphorylation. If it occurs in the presence of light, it is called photophosphorylation, that occurs during photosynthesis in the chloroplast. Mitochondria perform oxidative and substrate level phosphorylation.

Hence, the correct answer is 'Chloroplast'

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

Which option is not correct for chemiosmotic theory?

  1. ATP synthesis is linked with proton gradient

  2. Break down of proton gradient releases energy

  3. ATPase enzyme act as pump to break proton gradient

  4. It is applicable for photo phosphorylation and oxidative phosphorylation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • There is a proton gradient created across the thylakoid membrane. The breakdown of this gradient is important because it leads to the release of energy. The gradient is broken down due to the movement of protons across the membrane to the stroma through the transmembrane channel ADP ATP of the F0 of the ATPase. 
  • The ATPase enzyme consists of two parts: F0 and F1. This breakdown provides enough energy to cause a conformational change in the F1 particle of the ATPase, which makes the enzyme synthesize ATP.

So, the correct option is 'ATPase enzyme act as a pump to break proton gradient'.

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

The total number of ATP produced when one molecule of glucose is partially oxidised into lactic acid is: 

  1. 2

  2. 10

  3. 8

  4. 36
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During glycolysis, one molecule of glucose is broken down into two molecules of pyruvate, yielding a net gain of 2 ATP. In lactic acid fermentation, the pyruvate is converted to lactic acid without further ATP production.