Chapter 8, Problem 1A

Summary Introduction

Introduction:

Pathogens are those organisms that have the capability of causing disease. Virus, bacteria or any other organisms are called as the pathogens.

Answer to Problem 1A

Correct answer:

The pathogen that possesses a plasmid is called as a bacterium. Therefore, option (c) is correct.

Explanation of Solution

Reasons for the correct statement:

A bacterium comes under the category of a prokaryotic cell, which does not have a nucleus. It possesses some circular, small pieces of DNA that are called as plasmids. There is presence of double stranded DNA in the nucleoid of bacteria.

Option (c) is given as “bacterium”.

“The pathogen that possesses a plasmid is called as a bacterium”, it is the right answer.

Hence, option (c) is correct.

Reasons for the incorrect statements:

Option (a) is given as “virus”.

The genetic material of viruses need not be DNA (deoxyribonucleic acid) or double stranded DNA only; it can even be RNA (ribonucleic acid). It does not have plasmid. So, it is a wrong answer.

Option (b) is given as “prion”.

Prions are the particles that are infectious and are comprised of proteins that degenerates the nervous system. So, it is a wrong answer.

Option (d) is given as “All of these are correct”.

Prions, viruses and bacteria, altogether do not possess plasmids. So, it is a wrong answer.

Hence, options (a), (b) and (d) are incorrect.

Conclusion

The pathogen that possesses a plasmid is called as a bacterium.