Question

In which of the following respiration takes place in absence of oxygen?
A) Man
B) Potato
C) Yeast
D) Spirogyra

Answer 1

Hint:Respiration is defined as the process through which organisms obtain energy. This energy is then used by the organism to carry out different metabolic processes.

Complete answer:
Respiration is broadly classified into two types-
1) Aerobic respiration, that occurs in the presence of oxygen.
2) Anaerobic respiration that occurs in the absence of oxygen.

Aerobic respiration requires oxygen to produce ATP, which is the primary energy source of the cells. The process begins with glycolysis where complex carbohydrates are broken down to simple ones and finally to pyruvate. This pyruvate is then oxidised in the mitochondria through the citric acid cycle to finally give carbon dioxide and water along with ATP produced by substrate level phosphorylation as well as $FADH_2$ and NADH. $FADH_2$ and NADH then undergoes the electron transport chain where oxygen is the terminal electron acceptor and ATP is produced by oxidative phosphorylation. Aerobic respiration takes place in man, plants, algae like Spirogyra, few bacteria such as Bacillus sp, Mycobacterium sp.

Anaerobic respiration is where electron acceptors other than oxygen are used such as sulphate, nitrate, fumarate, etc. the pyruvate produced by glycolysis enters into the cytoplasm instead of the mitochondria and generates ATP. Though the number of ATP generated in anaerobic respiration is less as compared to aerobic respiration. Anaerobic respiration takes place in Actinobacteria, yeast, Clostridium, Fusobacterium, etc.

Hence the correct answer is option (C) Yeast.

Note: Respiration is one of the most important phenomena in organisms since it provides them with energy. Few organisms are capable of anaerobic respirations when conditions are not favourable for aerobic respiration. They are known as facultatives and this property gives them a survival advantage over the obligate ones.