Chapter 1, Problem 1SQ

Summary Introduction

Introduction:

To characterize an organism as living, it must perform certain functions like growth and development, carry out different metabolic processes like respiration, digestion, excretion and more, and also it must reproduce and carry out functions essential for life.

Answer to Problem 1SQ

Correct answer:

All the living organisms are not multicellular. Rather, the majority of living beings are unicellular. Therefore, option b is correct.

Explanation of Solution

Reason for the correct statement:

Life on Earth started as a single cell. Over a period of billions of years, these unicellular organisms gave rise to multicellular beings. However, this advent of multi-cellular organisms did not cease the existence of unicellular organisms. Moreover, two of the five kingdoms are completely composed of unicellular organisms (monera prokaryotes. and protista eukaryotes). Single-celled organisms are present in other kingdoms too.

Option b is given as “composed of multiple cells”.

As “being a multicellular organism is not an essential characteristic of life,” it is the right answer.

Hence, option b is correct.

Reasons for the incorrect statements:

Option a is given as “growth and development”.

All organisms grow and develop. It is the elementary purpose of life. Thus, it is a characteristic of life seen in all organisms. So, it is a wrong answer.

Option c is given as “complex yet organized”.

Though a lot of organisms are primitive like the bacteria, they still are organized and complex. Thus, it is a life characteristic of all the organisms. So, it is a wrong answer.

Option d. is given as “uses energy”.

All living organisms perform metabolic processes to survive for which they have to utilize energy. Thus, this is a characteristic of life seen in all the living beings. So, it is wrong answer.

Hence, options a., c. and d. are incorrect.

Conclusion

Multicellularity is not a characteristic of life evident in all the organisms. Most of the organisms on Earth are unicellular and thus they can sustain life with just a single cell.