Question

Bacteria do not have chloroplast but some bacteria are photoautotrophic in nature and perform photosynthesis. Which part of the bacterial cell performs this?
A. Small vesicles associated with plasma membrane
B. Mitochondria
C. Ribosomes
D. None of the above

Answer 1

Hint: The organelles that conduct photosynthesis are called chloroplasts. Bacteria usually do not possess chloroplast but some of them are photoautotrophic and have the ability to perform photosynthesis. Cyanobacteria are examples of these kinds of bacteria. A group of photosynthetic bacteria, some of which are nitrogen-fixing, are called cyanobacteria.

Complete answer:
Option A Small vesicles associated with plasma membrane: Although bacteria cells do not possess chloroplast, some photoautotrophic bacteria are able to perform photosynthesis. The presence of chlorophyll integrated in the cell membrane accomplishes this. In the cell membrane, there are reaction centers embedded which help to absorb light energy. These reaction centers exist in the form of small vesicles or tubes or sheets depending upon the needed surface area. Hence option A is the correct answer.
Option B Mitochondria: The main purpose of mitochondria is to serve as batteries, powering various functions of the cell and the organism as a whole. Although mitochondria are an integral part of the cell, many evidences show that mitochondria have been evolved from primitive bacteria. They also do not have the ability to perform photosynthesis. Hence option B is not correct.
Option C Ribosomes: The main function of ribosomes is to produce proteins from amino acids during the process called protein synthesis or translation. In bacteria and archaebacteria, ribosomes are present. These are smaller ribosomes, which are composed of a small subunit and a large subunit. Since ribosomes cannot perform photosynthesis, option C is not the correct answer.
Option D None of the above: Of the above given option, we have a correct answer which is option A. Hence option D is not correct.

So, Option A. Small vesicles associated with plasma membrane, is the correct answer.

Note:
The photoautotrophic bacteria may perform either oxygenic photosynthesis or anoxygenic photosynthesis. These kinds of bacteria are used in biofertilizers, for bioremediation, waste water treatment and for purification of polluted water. The types of photoautotrophic bacteria are: Oxygenic Photosynthetic Bacteria, Anoxygenic Photosynthetic Bacteria, Purple Sulphur bacteria (PSB), Purple non-Sulphur bacteria (PNSB) and Green Sulphur bacteria (GSB).