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 biology life processes in living organisms- part 1 fermentation cell respiration living organisms and energy production

Buchner was successful in extracting a respiratory enzyme complex

  1. ATP

  2. NADH

  3. Zymase

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

Eduard Buchner was a German chemist who won the Noble prize in chemistry for his chance discovery in 1907. His brother Hans Buchner was a physician who conducted early research on blood proteins that could destroy bacteria. Eduard Buchner assisted his brother in his research. He produced yeast cell-free extracts for his brother who wanted to use them for immunological applications. In order to preserve the protein extract from yeast cells, he added sugar and while doing this he noticed the formation of bubbles. This meant that carbon dioxide and alcohol were being produced. Buchner had obtained an enzyme mixture called zymase from yeast that caused glycolysis and transformed the sugar into alcohol. Thus he discovered zymase, a complex of the enzyme that caused glycolysis in 1903. 

Thus, the correct answer is option C. 

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

In respiratory process which step is not related with decarboxylation?

  1. Alcoholic fermentation

  2. TCA cycle

  3. Oxidative decarboxylation of Pyruvate

  4. Lactic acid fermentation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
 Name of process   Decarboxylation occurence
 Alcoholic fermentation  Pyruvate (3C) $\rightarrow$  Acetaldehyde (2C)
 TCA cycle  Isocitrate$\rightarrow$ $\alpha$ ketoglutarate
 Oxidative decarboxylation Pyruvate $\rightarrow$ Acetyl CoA
 Lactic acid fermentation  No decarboxylation process occurs

So, the correct answer is ' Lactic acid fermentation '.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

In anaerobic respiration of yeast

  1. ${ O } _{ 2 }$ is given out
  2. ${ CO } _{ 2 }$ is given out
  3. ${ CO } _{ 2 }$ is taken in
  4. ${ O } _{ 2 }$ is taken in
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yeast respires anaerobically (in the absence of oxygen) . The process is known as fermentation. Glucose is the respiratory substrate.

The glucose is converted to pyruvate by the process of glycolysis. This process is independent of oxygen. If oxygen is absent, the pyruvate is broken by yeast into ethanol releasing carbon dioxide along with the production of 2 ATP.
So, the correct answer is 'CO$ _2$ is given out'.

Multiple choice biology life processes in living organisms- part 1 fermentation cell respiration living organisms and energy production

During fermentation what does not occurs ___________________.

  1. Oxidation of glucose into pyruvate

  2. Substrate level phosphorylation
  3. Oxidation of $NADH _2$

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

Answer is option D i.e. "Oxidative phosphorylation"
Fermentation occurs only when there is no oxidative phosphorylation to maintain the production of ATP by glycolysis. During fermentation, pyruvate is metabolized to various compounds such as lactic acid, ethanol and carbon dioxide or other acids. Also, fermentation reactions occur in the cytoplasm while oxidative phosphorylation occurs in mitochondria.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

Select the number of incorrect statements for the process of fermentation.
A . It involves only partial breakdown of glucose.
B $NADH _2$ is oxidized to NAD by reduction of organic compound.
C. No ATP are produced during fermentation as it is extracellular process in some microbes.
D. There is no ETS and Kreb's cycle.
E. Maximum concentration of alcohol in alcohol in alcoholic brevarage is 100 %.

  1. 2

  2. 3

  3. 4

  4. 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Fermentation can be defined as the partial breakdown of glucose to produce ethyl alcohol and carbon dioxide.
  • It releases energy in form of  ATP molecules.
  • 2 ATP molecules are produced per glucose.
  • 2NADH molecules provide energy which converts pyruvate into lactic acid.
  • The maximum concentration of alcohol in alcoholic beverages is 15%-16%.
  • Option C and E are incorrect statements.
  • So, the correct answer is'2'.
Multiple choice biology life processes in living organisms- part 1 fermentation cell respiration living organisms and energy production

The energy releasing metabolic process in which substrate is oxidized without an external electron acceptor is called as

  1. Photorespiration

  2. Glycolysis

  3. Fermentation

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

Fermentation is incomplete oxidation of food substances in absence of oxygen (external electron acceptor) into alcohol or lactic acid with the small amount of energy being released. Aerobic respiration uses oxygen as an electron acceptor for oxidation of substrates. Glycolysis is the first common stage of both fermentation and aerobic respiration. Photorespiration is oxidation of RuBP by enzyme RUBISCO and does not produce energy. Thus, the correct answer is option C.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

Glucose is oxidised to ethyl alcohol during the process of

  1. Respiration.

  2. Aerobic respiration.

  3. Anaerobic respiration.

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

The process of anaerobic respiration takes place in the absence of oxygen. In this type, glucose is oxidized to ethyl alcohol, and it releases carbon dioxide. For example, breathing in yeast is a type of anaerobic respiration.

So, option C is the correct answer.

Multiple choice biology life processes in living organisms- part 1 fermentation cell respiration living organisms and energy production

The formation of NAD via anaerobic pathway takes place by

  1. Glycolysis.

  2. Fermentation.

  3. Krebs cycle.

  4. Electron transport chain.

  5. Photosynthesis.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In anaerobic conditions, glycolysis produces NADH. To continue glycolysis, NADH must be oxidized back to NAD+, which occurs during the fermentation process.

Multiple choice biology life processes in living organisms- part 1 fermentation cell respiration living organisms and energy production

A sudden change from anaerobic to aerobic process produces ________________.

  1. Pasteur effect

  2. Emerson effect

  3. Blackmans law

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

Answer is option A i.e. "Pasteur effect"
Pasteur effect is exhibited in yeast cells during anaerobic fermentation. Pasteur effect influences the rate of glycolysis and occurs in presence of oxygen which  decreases the rate of sugar breakdown in yeast.
While, Blackman's law and Emerson effect is related to determining the rate of  photosynthesis. Chargraff's rule is a rule for base equivalence in DNA.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

Anaerobic process after glycolysis is known as

  1. TCA cycle

  2. Krebs cycle

  3. Calvin cycle

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

A) Lactic acid fermentation is the process that occurs after glycolysis when there is lack of oxygen.

B) TCA or Krebs cycle occurs glycolysis in the presence of oxygen and converts Acetyl coenzyme into oxaloacetic acid to yield ATP.
C) Calvin cycle is the common pathway for $C _3$ and $C _4$ plants.
So the correct option is 'None of the above'.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

 Anaerobic respiration of animals/humans produces

  1. Glucose and O$ _2$
  2. C$ _2$H$ _5$OH and CO$ _2$

  3. Lactic acid and water
  4. CO$ _2$ and H$ _2$O
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cellular respiration in animals is predominantly aerobic in nature. However in stressful conditions, the respiration turns anaerobic to meet the energy demands. End products of anaerobic respiration are lactic acid and water. End products in plants for aerobic respiration are alcohol and carbon dioxide.

So the answer is 'Lactic acid and water'.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

Three major ways for metabolism of pyruvic acid produced in glycolysis are

  1. Lactic acid fermentation, alcoholic fermentation and aerobic respiration.

  2. Oxaloacetic acid fermentation, lactic acid fermentation, aerobic fermentation.

  3. Alcoholic fermentation, oxaloacetic acid fermentation, citric acid fermentation.

  4. Citric acid fermentation, lactic acid fermentation, alcoholic fermentation.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis the common pathway of lactic acid fermentation, alcoholic fermentation and aerobic respiration in which glucose is converted into pyruvic acid in a multi-step reaction which includes ten major steps involve various enzymes.

So the correct option is 'Lactic acid fermentation, alcoholic fermentation and aerobic respiration.'

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

The incomplete breakdown of sugars in anaerobic respiration results in the formation of 

  1. Fructose and water
  2. Glucose and $CO _{2}$
  3. Alcohol and $CO _{2}$
  4. Water and $CO _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Anaerobic respiration involves the incomplete breakdown of glucose. It releases around 5% of the energy released by aerobic respiration, per molecule of glucose. In yeast it can be observed, as alcoholic fermentation. A biological process in which molecules such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products.

Multiple choice biology respiration in plants fermentation cell respiration living organisms and energy production

In anaerobic respiration, acetaldehyde is reduced to form alcohol by utilising $NADH _2$ obtained from

  1. Glycolysis

  2. Terminal oxidation

  3. Krebs cycle

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

Anaerobic respiration starts with the process of glycolysis. The NADH2 thus formed from glycolysis are used to further oxidise acetaldehyde to form alcohol and CO2. The NAD formed are then recycled back to be used in glycolysis.

So the answer is 'Glycolysis'.