(a) It would have contributed in disturbing the ecological balance of the pond/lake or any such water bodies.
(b) He is environment friendly because he is conserving biodiversity and not destroying species unnecessarily.
(c) By spreading awareness in the community members about the importance of diversity, by developing empathy and love for all living organisms.

(a) (i) They have a dorsal nerve cord.
(ii) They are triploblastic and have coelom.
(b) Pseudocoelom. The body cavity which is not lined by mesodermal layers and space is filled by large vacuolated cells is called pseudocoelom.
True coelom. It is a large perivisceral cavity between the body wall and alimentary canal. It is lined by parietal epithelium on both the sides.

(i) They are unicellular, eukaryotic organism i.e., they have membrane-bound nucleus and organelles.
(ii) Some of these organism use appandages such as hair-like cilia or whip-like flagella for moving around.
(iii) Their mode of nutrition can be autotrophic or heterotrophic.
Examples: Unicellular algae (like Chlamydomonas, Chlorella), diatoms and protozoans like Amoeba.
(iv) Primarily they are aquatic but can be parasite.

Range of Variations
(i) Life span-Mosquitoes live for a few days whereas cow, dog, etc. live for many years.
(ii) Colour-Some organisms like certain cows, horses, dogs are white but some birds and flowers are brightly coloured.
(iii) Size-Some organisms are so small that we cannot see them with naked eyes. On the other hand, eucalyptus tree is several metre tall.

The basis for grouping organisms into five kingdoms are:
(i) Whether the organisms are made of prokaryotic or eukaryotic cells.
(ii) Whether the organism is unicellular i.e., a cell living singly or organised into multicellular and thus complex organisms.
(iii) Whether the cells have a cell wall or not.
(iv) Whether they prepare their own food or get their food from outside.

We classify organisms due to the following reasons:
(i) Classification makes the study of huge varieties of organisms easy.
(ii) It reveals before us a picture of all forms of organisms at a glance.
(iii) It helps us to understand the interrelationship among different groups of organisms.
(iv) It serves as a base for the development of other pure biological science e.g., biogeography i.e., geographical distribution of plants and animals.
(v) It also helps in understanding and development of other applied branches of science such as agriculture, public health and environmental biology.

Difference between Bryophyta and Pteridophyta:

The primary characteristic on which the first division of organisms is made is the nature of the cell. It is considered to be the fundamental characteristic for classifying all living organisms. Nature of the cell includes the presence or absence of membrane-bound organelles. Therefore, on the basis of this fundamental characteristic, we can classify all living organisms into two broad categories of eukaryotes and prokaryotes. Then, further classification is made on the basis of cellularity or modes of nutrition.