Biology

Cellular Respiration and Enzymes

1,551 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 biology respiration in living organisms breathing in plants mode of respiration in plants process of respiration

Consider the following statements.
a. Acetaldehyde is an electron acceptor during respiration
b. In Critic Acid Cycle, pyruvate is transported from cytosol to mitochondrial matrix
c. The Pentose Phosphate Pathway occurs in cytosol
Which of these statements are correct?

  1. $1, 2$ and $3$
  2. $1$ and $2$
  3. $2$ and $3$
  4. $1$ and $3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology concept of life living organism living vs nonliving living vs non living

Growth occurs when 

  1. Anabolism is higher than catabolism

  2. Catabolism is higher than anabolism

  3. Protoplasmic synthesis is more than apoplasmatic synthesis

  4. Apoplasmatic synthesis is more than protoplasmic synthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Growth occurs when the anabolic (Constructive activities) exceed the catabolic activities (destructive activities).

So the correct option is A.

Multiple choice biology concept of life living organism living vs nonliving living vs non living

Growth occurs when

  1. Anabolism is higher than catobolism

  2. Catabolism is higher than anabolism

  3. Protoplasmic synthesis is more than apoplasmatic synthesis

  4. Apoplasmatic synthesis is more than protoplasmic synthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The irreversible permanent increase in size, volume or weight of the body is called Growth. It is the cumulative effect of cell division, cell elongation and cell differentiation. During growth, in the cells, rate of metabolism is high. So, synthesis and breakdown of biomolecules takes place. In this synthesis of biomolecules is higher than breakdown of biomolecules. So the rate of anabolism is greater than catabolism.

So, correct option is ‘Anabolism is higher than catabolism’.

Multiple choice factors affecting respiration living organisms and energy production life processes in living organisms- part 1 respiration biology

Consider the following statements w.r.t. respiration 
a. Cyt-b is a mobile electron carrier
b. $CO _2$ is end product of all types of respiration
c. Five atoms of oxygen are required for complete oxidation of one molecule of pyruvate
d. Conversion of succinate to fumarate produces a reduced coenzyme.

  1. a & c are incorrect

  2. Only d is correct

  3. a & d are correct

  4. b & d are correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cyt-b is part of ETS which act as an electron carrier and formation of ATP whereas CO$ _2$ is the only end product of anaerobic respiration. conversion from succinate to fumarate produces a reduced coenzyme known as succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR).

So the correct option is 'a & c are incorrect'

Multiple choice factors affecting respiration living organisms and energy production life processes in living organisms- part 1 respiration biology


For aerobic respiration to occur

  1. Pyruvate must be transported to the mitochondrion

  2. Oxygen must be available to the mitochondrion

  3. Hydrogen ions released from the breakdown of pyruvate must be carried to the electron transport system

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

  • Aerobic respiration is the process that takes place in the presence of oxygen.
  • The first part of the process is where the molecule of glucose is broken down to 2 molecules of pyruvate by the process of glycolysis
  • These pyruvate molecules are to enter the mitochondria to under go the reaction of kerb cycle, but the molecule of pyruvate itself cannot enter the mitochondria, it is converted to acetyl CoA so that it can enter inside the mitochondrion membrane.
  • After the kerb cycle molecules of NADH and $FADH _2$are formed which enter the ETS and undergo oxidative phosphorylation.
  • Hydrogen ions are released from the NADH and $FADH _2$ molecules which are transported from inner membrane of mitochondria to the intermembrane matrix of mitochondria, this builds a concentration gradient across the membrane. Also the hydron ions and the electrons that are transported by the complexs of the ETS are in the end accepted by the oxygen molecule forming water that is why it is known as oxidative phosphorylation
  • The concentration gradient that is made is used for the transport of hydronium ions across the ATP synthase complex of the inner mitochrondrial membrane. 
  • With the transport of 2 hydrogen ions one molecule of ATP is formed.
  • Thus glycolysis which takes place in cytoplasm, Kerb cycle that takes place in mitochondria , oxidative phosphorylation and chemisomotic phosphorylation are the parts of aerobic respiration.
  • Therefore the answer 'All of the above' is correct.

















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

Which of the following element participate in oxidation of glucose to form ATP?

  1. Calcium

  2. Sodium

  3. Magnesium

  4. Potassium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Option $(D)$ is correct.
Potassium participates in the oxidation of glucose to form ATP through  ATP-sensitive potassium channel. 
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'.