12.2.2

Anaerobic Respiration

Test yourself on Anaerobic Respiration

Test your knowledge with free interactive questions on Seneca — used by over 10 million students.

Anaerobic Respiration

The end product of glycolysis is pyruvate and this can then be used in aerobic or anaerobic respiration. There are two types of anaerobic respiration: ethanol fermentation and lactate fermentation.

Ethanol fermentation

Ethanol fermentation

  • Ethanol fermentation is the conversion of pyruvate to ethanol under anaerobic conditions.
  • This process only takes place in plants and yeast.
Pyruvate → ethanol

Pyruvate → ethanol

  • Pyruvate is first converted to ethanal by the enzyme pyruvate decarboxylase.
    • CO2 is produced as a by-product.
  • Ethanal is then reduced to ethanol.
    • This reaction is catalysed by ethanol dehydrogenase.
    • NADH is oxidised to NAD.
Rice

Rice

  • Rice plants grow with their roots submerged in water. Their roots depend on ethanol fermentation to get a lot of their energy.
  • The roots of rice plants are able to withstand high levels of ethanol.
  • Rice stems also contain aerenchyma tissue.
    • This is a spongy tissue that allows easy, low-resistance gas exchange between the above water and submerged parts of the plant.
  • This allows the roots to get access to some oxygen even though they are submerged.
Lactate fermentation

Lactate fermentation

  • Lactate fermentation is the conversion of pyruvate to lactate.
  • This process takes place in animals and some bacteria. It is common in skeletal muscle when there is an insufficient oxygen supply, such as during exercise.
  • The lactate is converted back to pyruvate when there is sufficient oxygen present.
    • The amount of oxygen required after exercise to do this is called an "oxygen debt".
Pyruvate → lactate

Pyruvate → lactate

  • Pyruvate is reduced to lactate.
    • This reaction is catalysed by lactate dehydrogenase.
    • NADH is oxidised to NAD.
Jump to other topics
1

Cell Structure

2

Biological Molecules

3

Enzymes

4

Cell Membranes & Transport

5

The Mitotic Cell Cycle

6

Nucleic Acids & Protein Synthesis

7

Transport in Plants

8

Transport in Mammals

9

Gas Exchange

10

Infectious Diseases

11

Immunity

12

Energy & Respiration (A2 Only)

13

Photosynthesis (A2 Only)

14

Homeostasis (A2 Only)

15

Control & Coordination (A2 Only)

16

Inherited Change (A2 Only)

17

Selection & Evolution (A2 Only)

18

Classification & Conservation (A2 Only)

19

Genetic Technology (A2 Only)

Practice questions on Anaerobic Respiration

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
  2. 2
Answer all questions on Anaerobic Respiration

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium