Q.1. Explain the characteristics of living organisms. Ans: Characteristics of living organisms are as follows: i. Growth: All living organisms exhibit growth. In living organisms growth is from inside, whereas in non-living organisms growth occurs due to accumulation of material on the surface. ii. Reproduction: Organisms reproduce asexually or sexually and produce their own kind. iii. Metabolism: Various biochemical reactions occur inside all living organisms. The sum total of all the reactions occuring in the body of an organism is called metabolism. iv. Cellular organization: Cell is the basic unit of life. All living organisms show cellular organization. v. Ability to sense and respond: All living organisms have ability to respond to the stimulus. Consciousness, is thus, one of the characteristics of living organisms.
Q.2. Why growth and reproduction cannot be the defining characteristics of living organisms? Ans: i. Growth is also exhibited by non-living objects. It is by accumulation of material on the surface. Thus, it cannot be taken as the defining property of living organisms. ii. Living organisms like mules, sterile worker bees, infertile human couples, etc. cannot reproduce. Thus, reproduction also cannot be the defining character of living organisms. 1.1 Diversity in living organisms.
Q.3. Explain diversity in living organisms. Ans: i. There are various types of living organisms existing on the earth, ranging from unicellular microscopic organisms to large multicellular plants and animals. ii. Some of them are prokaryotic in nature, while some are eukaryotes. iii. There are about 5 − 30 million species of plants and animals on earth. iv. They exhibit a great deal of variation in shape, size, structure, mode of nutrition, mode of reproduction, etc. v. They live or grow in different climatic conditions.
Q.4. Why are living organisms classified? Ans: Living organisms are classified due to following reasons: i. Study of fossils ii. Study of organisms of different areas iii. For easy identification iv. Grouping based on the similarities and differences v. Evolution of various taxon, etc.