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 respiration-the energy producing system anaerobic respiration in organisms anaerobic and aerobic respiration cellular respiration

Glycolysis yields approximately ___ percent of the total energy of glucose.

  1. 5%

  2. 10%

  3. 15%

  4. 2%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis is the initial stage of glucose breakdown, occurring in the cytoplasm. It yields a small amount of energy compared to the complete oxidation of glucose in the Krebs cycle and electron transport chain, accounting for approximately 5% of the total energy.

Multiple choice respiration-the energy producing system anaerobic respiration in organisms anaerobic and aerobic respiration cellular respiration

How many PGAL are produced by glycolysis of three molecules of glucose? How many ATP are released by respiration of these PGAL till formation of $CO _2$ and $H _2O$ 

  1. 4 PGAL 40 ATP

  2. 6 PGAL 120 ATP

  3. 4 PGAL 80 ATP

  4. 5 PGAL 160 ATP
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

One glucose molecule produces 2 PGAL (G3P) during glycolysis. Therefore, 3 glucose molecules produce 6 PGAL. The complete respiration of 6 PGAL (via Krebs cycle and ETC) yields 120 ATP (since 1 glucose yields 38 or 36 ATP, and 3 glucose yields roughly 114-120 ATP).

Multiple choice zoology molecular genetics one gene - one enzyme hypothesis component of the cell cell and cell organelles

Activator of phsphofructokinase enzyme is:

  1. AMP

  2. ATP

  3. CN

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

AMP is known as Adenosine monophosphate which is involved in many biological processess. It is a type of nucleotide phosphate. It  consists of phospate group and nucleobase adenine. It is used to regenerate ATP.

So, the correct option is 'AMP'.

Multiple choice bio-chemistry digestive system of human absorption mechanism absorption digestion


Which of the following pathways would increase its activity level during starvation?

  1. Fatty acid degradation

  2. Amino acid synthesis

  3. Fatty acid synthesis

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • During starvation the priority of the metabolism in body is to provide sufficeint glucose to the brain and other tissues that are absolutely dependent on this fuel,. 
  • However precursors of the glucose are not abundant at the time of starvation and most of the stored fatty acid is utilised at times like this.
  • These fatty acid cannot be converted to glucose because acetyl CoA cannot be transformed to pyruvate.
  • Therefore the fatty acid that are stored in the body are converted to acetyl CoA and are used in the metabolism to provide energy to the body in the state of starvation.
  • Therefore the answer option 'Fatty acid degradation' is correct.
Multiple choice zoology respiration in organisms respiration in human beings respiration and associated structures respiration in humans

Select the wrong statement(s) about respiration.
a) It consists of breathing, oxidation of food and energy storage in the form of ATP.
b) Cytoplasm and mitochondria are necessary for the completion of aerobic respiration.
c) Complete oxidation of food into ethanol or lactic acids, $CO _2$ and few molecules of ATP are seen in anaerobic respiration.
d) In the older portions of woody plants, the gaseous exchange takes place through stomatal apertures.
Statements that are entirely wrong are

  1. a) and b)

  2. b) and c)

  3. a) and d)

  4. c) and d)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Anaerobic respiration takes place in the absence of oxygen. So, oxidation of food does not take place. So, statement c is wrong. Gaseous exchange occurs through leaves that have minute tiny apertures over them called stomata. 

Statement a and b are true. We know that respiration consists of breathing, which includes inhalation and exhalation, oxidation of food and also it stores energy the form of ATP. The cytoplasm is the jelly-like fluid matrix that contains different cell organelles like mitochondria. All the steps of cellular respiration occur inside mitochondria.
So, statement (c) and (d) are wrong statements and option D is the correct answer.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

Which of the following statements is false ?

  1. ${\text{M}}{{\text{g}}^{{\text{2 + }}}}$ ion form a complex with ATP
  2. ${\text{C}}{{\text{a}}^{{\text{2 + }}}}$ on are important in blood clotting
  3. ${\text{C}}{{\text{a}}^{{\text{2 + }}}}$ ion are not important in maintaining the regular beating of the heart.
  4. ${\text{M}}{{\text{g}}^{{\text{2 + }}}}$ ion are important in the green parts of plants.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Calcium ions (Ca2+) are crucial for muscle contraction, including the rhythmic contraction of cardiac muscle (heartbeat). Therefore, the statement that they are not important in maintaining the regular beating of the heart is false.

Multiple choice zoology heredity and variation effects of smoking smoking tobacco drugs

Smokers metabolize nicotine to form

  1. Uric acid

  2. Urea

  3. Cotinine

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nicotine is a major constituent of tobacco, which plays a critical role in smoking addiction. In humans, nicotine is primarily metabolized to cotinine, which is further metabolized to trans-3'-hydorxycotinine.
Thus, the correct answer is option (C), 'Cotinine'.

Multiple choice zoology respiratory system experiments on photosynthesis cellular respiration introduction to respiration

Which of the following options contains the end products formed during anaerobic respiration in yeast?

  1. $H _2O, CO _2$ and energy
  2. $H _2S, C _6H _{12}O _6$ and energy
  3. $CO _2, C _2H _5OH$ and energy
  4. $H _2O$ and $CO _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Anaerobic respiration in yeast results in the production of ethyl alcohol, carbon dioxide and energy. $C _6H _{12}O _6 \xrightarrow[Complex]{Zymase} \underset{Ethyl \, alcohol}{2C _2H _5OH} + 2CO _2 + $

Multiple choice zoology respiratory system experiments on photosynthesis cellular respiration introduction to respiration

Respiration oxidizes

  1. Glucose

  2. Carbon

  3. Nitrogen

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Respiration is a catabolic process that takes place in living organisms. In this glucose is broken down in presence of oxygen to generate ATP along with the production of water and evolution of carbon dioxide. It is an exergonic process. Thus the correct answer is option A.

Multiple choice zoology respiratory system experiments on photosynthesis cellular respiration introduction to respiration

In respiration the energy is produced during the process of

  1. Glycolysis

  2. Krebs cycle

  3. Glycolysis and Krebs cycle

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

Glycolysis is the first step of respiration which converts the glucose molecules into two molecules of pyruvate along with the production of 8 ATP. The two pyruvate molecules produced by the glycolysis enters the Krebs cycle. Each molecule of pyruvate produces 15 ATP. So total 30 ATP is formed during the Krebs cycle. Total 38 ATP is formed during the aerobic respiration.

So, the correct answer is option C.

Multiple choice zoology respiratory system experiments on photosynthesis cellular respiration introduction to respiration

The common immediate source of energy in cellular activity is

  1. ADP

  2. ATP

  3. FAD

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

ATP is an Adenosine triphosphate (ribose sugar, adenine base, and three phosphate groups), where a high energy bond attaches the third phosphate group to the molecule. The highly unstable bonds break to release the inorganic phosphate to fulfill the energy required for the metabolism.

Hence, the correct answer is option B.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Movement of ten electrons from mitochondrial NADH molecules produces water molecules

  1. 20

  2. 15

  3. 10

  4. 5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the electron transport chain, each NADH molecule provides 2 electrons. 10 electrons (from 5 NADH molecules) react with oxygen to form 5 water molecules (since 4 electrons are required for 1 O2 to form 2 H2O).

Multiple choice bio-chemistry organization of life concept of metabolism metabolism in animals metabolism

Respiration is a

  1. Anabolic process

  2. Deamination process

  3. Catabolic process

  4. Both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The breaking of the C-C bonds of complex compounds through oxidation within the cells, leading to the release of a considerable amount of energy is called as respiration. As carbon-carbon covalent bonds are broken, it is a catabolic process. Respiration involves the synthesis of energy in form of ATP. The synthesis of ATP leads to the formation of several covalent linkages of phosphates. There is synthesis which are included in the anabolic processes.

Thus, the correct answer is option D.

Multiple choice bio-chemistry organization of life concept of metabolism metabolism in animals metabolism

Catabolic and anabolic pathways are often coupled in cell because

  1. Both the paths have the same energy

  2. The free energy released from one pathway is used to drive other

  3. The intermediates of a catabolic pathway are used in the anabolic pathway

  4. Their enzymes are controlled by their activators and inhibitors.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Anabolic pathways are those that require energy to synthesize larger molecules. Catabolic pathways are those that generate energy by breaking down larger molecules. Both types of pathways are required for maintaining the cell's energy balance.
  • Catabolic and anabolic pathway are coupled because catabolic reactions furnish the energy required for anabolism. Catabolic reactions transfer energy from complex molecules to ATP. Anabolic reactions transfer energy from ATP to complex molecules.
  • Hence Catabolic and anabolic pathways are often coupled in the cell because the free energy released from one pathway is used to drive other.
  • So, the correct answer is 'the free energy released from one pathway is used to drive other'.
Multiple choice bio-chemistry organization of life concept of metabolism metabolism in animals metabolism

Which of the following activity is catabolic in nature?

  1. Cell repair

  2. Protoplasm synthesis

  3. Degradation of amino acid in liver

  4. Conversion of glucose to glycogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Catabolism involves the breakdown of a substance, often to release energy or during excretion for removal of waste. Degradation of amino acids in the liver is such an example where amino acids are broken down into inorganic substituents for recycling or removal.

Cell repair, protoplasm synthesis and conversion of glucose to glucose are all examples of anabolism which involves the synthesis of a product.
So the correct answer is 'Degradation of amino acids in the liver'.