Biology

Cellular Respiration and Enzymes

1,721 Questions

Explore key concepts of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain. These questions also cover ATP production, anaerobic respiration, and essential metabolic pathways. This topic forms a core part of the biology syllabus for many competitive examinations.

Glycolysis and metabolic pathwaysKrebs cycle processesElectron transport chainATP production countAnaerobic respiration products

Cellular Respiration and Enzymes Questions

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

Select the correct option:

Study the following statements regarding chemiosmotic hypothesis in mitochondria and select the correct ones.
(i) ${F} _{1}$ headpiece contains the site for the syntesis of ATP from ADP+Pi.
(ii) ${F} _{0}$ part forms the channel through which protons cross the inner membrane.
(iii) For each ATP produced, ${2H}^{+}$ pass through ${F} _{0}$ from the intermembrane space to the matrix down the electrochemical proton gradient.

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iii)

  4. (i),(ii) and (iii)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  In the given question, the correct statements are as follows:

(i) F1 headpiece contains the site for the synthesis of ATP from ADP+Pi.

(ii) F0 part forms the channel through which protons cross the inner membrane.

(iii) For each ATP produced, 2H+ pass through F0 from the intermembrane space to the matrix down the electrochemical proton gradient.

So, the correct answer is '(i),(ii) and (iii)'.

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


During chemiosmotic synthesis of ATP, protons diffuse through $CF {0}$ channels that activates ATPase enzyme. As a result, one molecule of ATP is formed when _______ passes through ATPase. 

  1. $4H^{+} $
  2. $H^{+} $
  3. $2H^{+} $
  4. $6H^{+} $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During chemiosmotic synthesis of ATP, protons diffuse through CFo channels that activates ATPase enzyme. As a result, one molecule of Atp is formed when two hydrogen ions pass through ATPase.

So, the correct option is '$2H^+$.

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

Which one respiratory complex is coupled with ETS for ATP synthesis?

  1. Complex I

  2. Complex III

  3. Complex IV

  4. Complex V
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

ATP synthase is also called complex V. It is the final enzyme in the oxidative phosphorylation pathway and utilizes the energy stored in a proton gradient across a membrane to drive the synthesis of ATP from ADP and phosphate (Pi).

So, the correct option is 'Complex V'.

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 .
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 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.

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

Read the following statements : 
a) $F _0$ part of ATPase is associated with breakdown of proton gradient.
b) A H - carrier contributes in creation of proton gradient.
c) Movement of electrons in ETS is coupled to pumping of protons into the lumen.
d) Formation of $NADPH + H^+$ is related with the creation of proton gradient.
How many of the above statements are correct ?

  1. Two

  2. One

  3. Four

  4. Three
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

How many ATP molecule could maximally be generated from one molecule of glucose, if the complete oxidation of one mole of glucose to $CO _{2}$ and $H _{2}O$ yields $686$ kcal and useful chemical energy available in the high energy phosphate bond of one mole of ATP is $12\ kcal$.

  1. Fifty-seven

  2. One

  3. Two

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

Using the same calculation as before: 686 kcal / 12 kcal/ATP = 57.16. The maximal number of ATP is 57.

Multiple choice biology ecology carbon cycling mineral coal carbon cycle

Biochemical cycle with gaseous phase is

  1. Carbon

  2. Sodium

  3. Phosphorus

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

Carbon is a gaseous cycle because it circulates through the atmosphere primarily as carbon dioxide. Elements like sodium, phosphorus, and magnesium are sedimentary cycles with no significant gaseous phase.

Multiple choice blackman's principle of limiting factors photosynthesis in higher plants biology

Starch of guard cells is converted into PEP through

  1. Hydrolysis

  2. Oxidation

  3. Dephosphorylation

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

(A) Hydrolysis is the breaking of the bond due to reaction with water. Starch in plants is converted into PEP through the breaking of bonds as it reacts with water.

(B) Oxidation is the process of gaining electrons.
(C) Dephosphorylation is the removal of a phosphate group by hydrolysis.
(D) Decarboxylation is the process of removal of the carboxyl group.
So, the correct answer is 'Hydrolysis'.

Multiple choice botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
ATP is considered a high-energy compound because under cellular conditions, 7.3 kcal per mole of energy is released when a bond is broken between the

  1. base adenine and the sugar ribose

  2. adenosine and the phosphate groups

  3. base adenine and the phosphate groups

  4. adenosine diphosphate and the third phosphate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Energy is stored in the covalent bonds between each phosphate group which makes up the tail of the molecule. The last phosphate bond holds the most energy (approx. 7.3 kcal/mole). It is called the pyrophosphate bond. In order to release it's energy to the body, ATP breaks down into ADP [Adenosine Diphosphate(2 phosphates)] and an inorganic phosphate group and releases energy from the pyrophosphate bond.

So, the correct option is 'Adenosine diphosphate and the third phosphate'.

Multiple choice botany organisms and their environment energy flow in food chain food chain and energy flow energy flow in ecosystem

Choose the correct answers from the alternatives given .
Which of the following metabolic processes can occur without a net influx of energy from some other process ?

  1. ADP $^+$ P $\rightarrow$ ATP $^+$ H2O
  2. $C _6$$H _{12}$$O _6$ $^+$ $6O _2$ $\rightarrow$ $6CO _2$ $^+$ $6H _2O$
  3. $6CO _2$ $^+$ $6H _2O$ $\rightarrow$ $C _6$$H _{12}$$O _6$ $^+$ $6H _2O$
  4. $CO _2$ + $2H _2O$ $\rightarrow$ $CH _4$ $^+$ $2O _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
C$ _6$H$ _1$$ _2$O$6$ + 6O$2$ $\rightarrow$ 6CO$2$ +6H$2$O in this process glucose breaks down to give its hydrogens to the oxygen, it really does not need a lot of energy to begin and to keep going. It simply needs a small spark and then it can keep going until its done.
So, the correct option is 'C$ _6$H$ _{12}$O$ _6$ + 6O$ _2$ $\rightarrow$ 6CO$ _2$ +6H$ _2$O'
Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

The product of hill reaction are

  1. ATP and $NADPH _{2}$ in chloroplast
  2. ATP and $NADPH _{2}$ in mitochondria

  3. Only oxygen
  4. $NADPH _{2}$, ATP and $O _{2}$ in chloroplast
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Experiments with isolated chloroplasts, in presence of oxidants like ferricyanides and benzoquinone (Hill reagents) were conducted by Hill in 1937 and 1939. By placing the isolated chloroplasts in sunlight, he noticed evolution of oxygen from water. Hill concluded that if there was suitable hydrogen acceptor in the medium it would have been reduced. Arnon 1951 and 1954 repeated the experiment of isolated chloroplast and concluded that, the hydrogen acceptor present in plants is NADP (Nicotinamide adenine dinucleotide phosphate). It is reduced to $NADPH _2$ and an ADP molecule is converted to ATP in light by utilizing inorganic phosphate. This phenomenon is called as photophosphorylation.