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

Catabolite repression allows cells to save energy by

  1. inactivating catabolic enzymes

  2. inhibiting synthesis of total RNA

  3. regulating expression of genes required for utilization of less-efficient metabolites

  4. inhibiting translation of mRNAs encoding catabolic enzymes
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

A new isolate of a facultative anaerobe utilizes either oxygen or pyruvate as terminal electron acceptor. This bacterium was grown either anaerobically with glucose as sole carbon source; or aerobically with lactose as the sole carbon source. Net increase in ATP production (per mole of the carbon source) during the aerobic growth would be

  1. 2 - fold

  2. 4 - fold

  3. 19 - fold

  4. 38 - fold
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aerobic respiration via oxidative phosphorylation yields approximately 36 to 38 ATP molecules per mole of glucose, compared to only 2 ATP molecules produced via anaerobic glycolysis. Thus, the net increase in ATP production during aerobic growth is a 19-fold increase (38 divided by 2).

Multiple choice respiration and excretion in animals human respiratory system evs respiration in human beings respiratory organs in humans respiration in humans

Respiratory quotient for three different substrates was calculated and tubulated as shown here.

Substrate R.Q.
XYZ 0.911.3

Identify X, Y and Z and select the correct option regarding them.

  1. X - Protein, Y - Fats, Z - Glucose

  2. X - Glucose, Y - Protein, Z - Organic acid

  3. X - Protein, Y - Glucose, Z - Organic acid

  4. X - Organic acid, Y - Protein, Z - Fats
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Respiratory quotient if the protein is 0.8-0.9

For glucose- 1
For  organic acids -1.3
So, the correct option is 'X - Protein, Y - glucose, Z - organic acids'.

Multiple choice

What molecule is produced when lipids break down?

  1. ATP

  2. DNA

  3. Starch

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

Lipids are broken down into fatty acids and glycerol, which then enter metabolic pathways to produce ATP, the primary energy currency of the cell.

Multiple choice botany mineral nutrition in plants mechanism of absorption mineral absorption significance of transpiration

Metabolic water is the one

  1. Used during transamination

  2. Used during photosynthesis

  3. Produced during aerobic utilization of glucose

  4. Produced during condensation or polymerisation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metabolic water is water produced by the body through metabolic processes. The aerobic respiration of glucose (C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy) releases water as a byproduct.

Multiple choice botany mineral nutrition in plants mechanism of absorption mineral absorption significance of transpiration

In feedback inhibition, a metabolic pathway is switched off by

  1. Lack of a substrate

  2. Accumulation of the end product

  3. A rise in temperature

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

Accumulation of the end product triggers inhibition or switching off of the metabolic pathway in feedback inhibition mechanism. 

So, the correct option is 'Accumulation of the end product'. 

Multiple choice biology the respiratory system anaerobic respiration in organisms anaerobic and aerobic respiration cellular respiration

The end product of anaerobic respiration, in plants, is

  1. Pyruvic acid

  2. Malic acid

  3. Ethyl alcohol

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

Anaerobic respiration refers to the type of respiration that takes place without oxygen. In plants, the glucose is anaerobically converted to ethyl alcohol, ATP and carbon dioxide.

Therefore, the correct answer is option C.

Multiple choice biology the respiratory system anaerobic respiration in organisms anaerobic and aerobic respiration cellular respiration

ATP is stored on the myosin cross bridges for immediate energy After 5 to 6 seconds, this supply is exhausted and the muscle must rely on to quickly produce more ATP.

  1. Phosphocreatine

  2. Lactic acid

  3. Acetyl choline

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

  • Myofibril activity is required for muscle contraction on the molecular level. 
  • When ATP binds to myosin, it separates from the actin of the myofibril, which causes a contraction.
  • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
  • ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
  • When ATP is exhausted lactic acid is produced 
So, the correct option is 'lactic acid'.

Multiple choice botany water absorption and ascent of sap in plants active transport and passive transport types of plant transport atp

ATP is required for

  1. Active process

  2. Passive process

  3. All types of processes

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

Active transport processes move substances against their concentration gradient, which requires energy in the form of ATP. Passive processes, such as diffusion or osmosis, occur spontaneously without the expenditure of metabolic energy.

Multiple choice botany water absorption and ascent of sap in plants active transport and passive transport types of plant transport atp

Which of the following shows that metabolic energy is required in the absorption of ions

  1. More ions absorption in presence of oxygen

  2. Less absorption of ions in presence of oxygen

  3. More ions absorption in presence of ATP

  4. More ions absorption in presence of NAD
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The absorption of ions, involving use of metabolic energy is called active absorption. Energy is generally obtained from ATP.Therefore active absorption is linked to hydrolysis of ATP

Multiple choice botany water absorption and ascent of sap in plants active transport and passive transport types of plant transport atp

Choose the correct answer from the alternatives given.
Active transport from outside to inside of molecules across a membrane requires:

  1. cyclic AMP

  2. acetyl chlorine

  3. ATP

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

Active transport, which is the movement of ions or molecules across a cell membrane in the direction opposite that of diffusion, that is, from an area of lower concentration to one of higher concentration, requires the assistance of a type of protein called a carrier protein, using energy supplied by ATP. So, the correct option is 'ATP'.

Multiple choice biology respiration in living organisms breathing in plants mode of respiration in plants process of respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O+ ATP
The given equation indicates which of the following activities in plants?

  1. Digestion

  2. Respiration

  3. Transpiration

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

Aerobic respiration takes place in the mitochondria and requires oxygen and glucose, and produces carbon dioxide, water, and energy. The chemical equation is 

C6H12O6 + 6O2 → 6CO2 + 6H2O+ ATP (glucose + oxygen -> carbon dioxide + water + ATP).
So, the correct option is 'Respiration'.

Multiple choice biology respiration in living organisms breathing in plants mode of respiration in plants process of respiration

Which of the following is the respiratory product in plants?

  1. Glucose

  2. Carbon dioxide

  3. Oxygen

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

The process by which cells obtain chemical energy by the consumption of oxygen and the release of carbon dioxide is known as respiration. In order to carry on respiration, plant cells need oxygen and a means of disposing of carbon dioxide just as animal cells do. In plants, each part such as root, stem performs respiration because plants do not possess any specialized organs like animals for the exchange of gases. 

Glucose + Oxygen → Carbon Dioxide + Water (+ Energy)We can conclude same from the above equation as well that respiration uses oxygen and produces carbon dioxide.

So, the correct option is 'Carbon dioxide'.

Multiple choice biology respiration in living organisms breathing in plants mode of respiration in plants process of respiration

During respiration in plants, the glucose is broken down into 

  1. Carbon dioxide

  2. Water

  3. Energy

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

The process by which cells obtain chemical energy by the consumption of oxygen and the release of carbon dioxide is known as respiration. In order to carry on respiration, plant cells need oxygen and a means of disposing of carbon dioxide just as animal cells do. In plants, each part such as root, stem performs respiration because plants do not possess any specialized organs like animals for the exchange of gases.

The process of respiration is expressed as:

Glucose + Oxygen → Carbon Dioxide + Water (+ Energy)

So, the correct option is 'All of the above'.