Question

In bacteria the site for respiratory activity found in
A. Episome
B. Microsome
C. Ribosome
D. Cell membrane/ Mesosome

Answer 1

Bacteria are the most primitive organisms and they are the first inhabitants of earth. Bacteria fall under the kingdom monera. They are unicellular, colonial or filamentous prokaryotic organisms. The enzymes which are used in the respiration are present in the plasma/cell membrane.

Complete answer:
In bacteria the site for respiratory activity is found in the cell membrane/ mesosome. Mesosomes are the folded invaginations in the plasma membrane of the bacteria which are produced by the chemical fixation technique. The mesosomes are invaginations of the plasma membrane first observed in the gram positive bacteria. Mesosomes help in the cell division, DNA replication and increase the surface area for the cellular respiration. Mesosomes are analogous to the cristae of the mitochondria. Mesosomes are rich in respiratory enzymes.
On the basis of mode of respiration, the bacteria divided into two main groups:
- Aerobes
- Anaerobes
Obligate aerobes: These bacteria live only in the presence of oxygen. They possess enzymatic systems for respiration, e.g., Bacillus subtilis.
Facultative aerobes: These bacteria normally respire anaerobically but they perform aerobic respiration in the presence of oxygen. Most of the photosynthetic bacteria are facultative aerobes, e.g., Chlorobium.
Obligate anaerobes: These bacteria respire through anaerobic respiration because they lack enzymes which are responsible for aerobic respiration, e.g., Clostridium botulinum.
Facultative anaerobes: They respire through aerobically but they are capable of switching over to anaerobic respiration to get energy for survival, e.g., Pseudomonas.

So the correct answer is option D.

Note: Bacteria are very economically important for human beings.
These help in the vinegar production (Acetobacter aceti).
There are some bacteria which help in the nitrogen fixing (Azotobacter and clostridium).
Bacteria produce antibiotics (Bacitracin: Bacillus licheniformis).