Question

Bacteria are thought to be primitive organisms because they
A. Are small, microscopic plants, which cannot be seen by naked eye
B. Cause serious diseases in human beings, domesticated animals and crops plants
C. Produce endospores which are very resistant to adverse conditions
D. Possess incipient nucleus and show division similar to amitosis

Answer 1

The biological cellular organisms are the living organism which take part in various processes such as growth, development and reproduction. The various organisms have arisen from simple sources and through various processes and evolved with the changing environment.

Complete answer:
Bacteria are a type of biological cells that are single celled microscopic organisms. The bacteria have various shapes and sizes and are cosmopolitan in distribution. They are known to be found in soil, water, acidic hot springs, radioactive waste and deep biosphere of the earth’s crust.
The bacteria consists of a cell and it is capable of performing all the various activities for development and reproduction. The cellular structure of bacteria shows a cell membrane that surrounds the cell. The bacterial cell lacks large membrane bound structures in their cytoplasm. The cell does not consist of organelles such as mitochondria and chloroplasts and other organelles that are present in the eukaryotic cells.
The nucleus in bacteria, is not a membrane bound nucleus. The genetic material lies freely in the cytoplasm and it includes a single circular bacterial chromosome of DNA. The genetic material consists of an irregular shaped body called the nucleoid.
The reproduction process of bacteria involves the division of the cell into two daughter cells. The division of the cell is related with both growth and reproduction. The bacterial cell divides through the process of binary fission which is a form of asexual reproduction. In this division, the cell division, the daughter cells, are clones of the parent cell. This division is similar to the process of amitosis. This characteristic of the bacterial cells exhibit that they are the first organisms to originate on earth and are primitive organisms.
The bacterial endospores are highly resistant, dormant structures and are produced in some species as a response to survive extreme environmental conditions.
Some species of bacteria are also pathogenic and cause several diseases in humans, animals and plants. They are responsible for various types of infectious diseases and cause damage to the crops.

Hence, the correct answer is option (D).

Note: Bacteria are prokaryotic single celled organisms. They do not contain a well-defined nucleus and the genetic material lies freely in the cytoplasm. They also do not contain membrane bound cell organelles such as mitochondria and chloroplast. The cell division takes place through binary fission which is similar to amitosis. Thus, they are thought to be the primitive organism.