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

What are the end products of aerobic respiration?

  1. Sugar and oxygen

  2. Water and energy

  3. Carbon dioxide and energy

  4. Sugar and carbon dioxide

  5. Carbon dioxide, water and energy
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Aerobic respiration occurs in all cells. It involves oxidation of food to give carbon dioxide, water and energy.

Multiple choice

In an animal cell, the first phase in the breakdown of glucose is

  1. fermentation

  2. ETS

  3. krebs cycle

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

Glycolysis is the first stage of cellular respiration in animal cells, occurring in the cytoplasm. It breaks down one glucose molecule into two pyruvate molecules, producing a net gain of 2 ATP and 2 NADH molecules. This anaerobic process precedes the Krebs cycle and electron transport system.

Multiple choice

In anaerobic respiration, there is a net gain of

  1. 2 ATP

  2. 3 ATP

  3. 38 ATP

  4. 10 ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Anaerobic respiration (glycolysis) yields a net gain of only 2 ATP per glucose molecule. This occurs in the cytoplasm when oxygen is absent. Aerobic respiration produces 36-38 ATP through complete glucose oxidation in mitochondria. The options of 3, 10, or 38 ATP do not match the known yield of anaerobic glycolysis.

Multiple choice

During anaerobic respiration_________.

  1. water and the carbon dioxide are the end products

  2. carbon dioxide and ethyl alcohol are the end products

  3. carbon dioxide and pyruvic acid are the end products

  4. oxygen and water are the end products

  5. only pyruvic acid is formed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbon dioxide and the ethyl alcohol are the end products in anaerobic respiration which occurs in the absence of oxygen.

Multiple choice

Respiration is considered as a ________.

  1. catabolic process

  2. anabolic process

  3. reduction process

  4. synthetic process

  5. metabolic process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is a catabolic process as in this, complex organic molecules are broken down into simple ones releasing large amounts of energy.

Multiple choice

What is being utilized in krebs cycle?

  1. Pyruvic acid

  2. Acetyl coA

  3. Oxaloacetate

  4. Both acetyl coA and oxaloacetate

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

Acetyl coA enters the krebs cycle and reacts with oxaloacetate to form citrate.

Multiple choice

______ is the series of reactions which results in the production of urea.

  1. Krebs cycle

  2. TCA cycle

  3. EMP pathway

  4. Ornithine cycle

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions occurring in many animals. Organisms that cannot easily and quickly remove ammonia usually have to convert it to some other substance, like urea or uric acid, which are much less toxic. Insufficiency of the urea cycle occurs in some genetic disorders (inborn errors of metabolism), and in liver failure. The result of liver failure is accumulation of nitrogenous waste, mainly ammonia, which leads to hepatic encephalopathy.