Question

What are the characteristics of anaerobic respiration?
A. Oxygen is not required.
B. Takes place in mitochondria.
C. End products are lactic acid or ethanol and carbon dioxide.
D. Both A and C.

Answer 1

Hint: Anaerobic respiration is a mode of respiration where sugar molecules are broken down in absence of oxygen to produce energy and other products.

Complete Answer:
- Respiration is a cellular process of energy generation from sugar or fat molecules. This energy is produced in the form of ATP and can be stored or used by cells. Different electron acceptors take part in the respiration process.

- Respiration is of 2 types: Aerobic and Anaerobic respiration.
(I) Aerobic respiration requires oxygen and mostly occurs in the mitochondria of a cell whereas anaerobic respiration does not require oxygen and takes place in the cell cytoplasm.
Cells in bacteria and Archaea perform anaerobic respiration in the cytoplasm. It is faster and uses sulphur or nitrate as electron acceptors instead of oxygen.
(II) Anaerobic respiration is majorly of two types: Lactic acid fermentation and alcoholic fermentation. During lactic acid fermentation in human muscle cells and bacterial cells, a glucose molecule is split into 2 lactic acid molecules and two molecules of ATP whereas in alcoholic fermentation a glucose molecule is broken down to produce 2 molecules of ethanol, 2 molecules of carbon dioxide and 2 molecules of ATP.

Thus, the correct answer is Option D: Both A and C.

Note: During prolonged and strenuous exercise, muscle cells of our body perform lactic acid fermentation for faster production of ATP. Buildup of lactic acid can cause cramping and sore muscles. Yeast cells perform alcoholic fermentation to produce wine and whiskey. This is applied in alcohol industries.