CBSE Class 9 Answered
1. The important divisions of Plantae are Thallophyta, Bryophyta, Pteridophyta, Gymnospermae and Angiospermae.
2. Thallophytes, Bryophytes and Pteridophytes possess inconspicuous reproductive organs and are called Cryptogams, Gymnosperms and Angiosperms are grouped under Phanerogamae, because they possess well-differentiated, seed-producing reproductive tissues.
3. Thallophytes (or algae) are the simplest plants lacking well-differentiated body design. They are autotrophic and lack mechanical and conducting tissues. Example: Spirogyra.
4. Bryophytes, such as moss and Riccia, show a differentiated plant body lacking true vascular tissues. They are simple land plants confined to shady damp places. They are also called amphibians of the plant kingdom.
5. Gymnosperms, such as pines and deodar, are phanerogams bearing naked seeds. The xylem lacks vessels and the phloem lacks companion cells.
6. In Angiosperms or flowering plants, the seeds are enclosed in fruits.
7. Cotyledons are present in the embryos of seeds. Cotyledons are called seed leaves because in some cases they emerge and become green when the seed germinates.
8. Monocotyledons possess seeds with a single cotyledon, whereas dicotyledons are plants with two cotyledons in the seeds.
9. Monocots show fibrous root system, parallel venation of leaves and flowers with three (or multiple of three) petals.
1. Animals are further divided into ten groups: Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, Protochordata and Vertebrata
2. In Porifera or sponges, the body is perforated by numerous pores and shows a cellular level of organisation. In addition, a hard exoskeleton and canal system are present. Sponges are non-motile. Mouth, digestive cavity and anus are absent. Example: Sycon.
3. Coelenterates are radially symmetrical and show a cavity called coelenteron between the epidermis and the gastrodermis. Some like Hydra are solitary forms, whereas others like corals live in colonies.
4. Platyhelminthes includes the flat worms which are bilaterally symmetrical, dorsoventrally flattened, triploblastic and acoelomate. They may be free-living (Planaria) or parasitic (tape worm).
5. Annelids are triploblastic, bilaterally symmetrical with true coelom and found in diverse habitats. Segmentation and extensive organ differentiation are seen. The alimentary canal is tube-like, complete and extends straight from the mouth to the anus. Examples: Earthworm and Nereis.
6. Arthropoda is the largest phylum of the Animal Kingdom and contains triploblastic, bilaterally symmetrical and segmented animals. These animals possess jointed legs and an open circulatory system. Examples: Butterfly, centipede, crab, spider etc.
7. In Mollusca, organisms show bilateral symmetry, soft body, open circulatory system and reduced coelom. Examples: Chiton, Pila.
8. Echinodermata includes spiny skinned organisms with calcareous skeleton. They are triploblastic, coelomate, marine and free-living. Examples: Starfish and Holothuria.
9. Vertebrates show a true vertebral column and endoskeleton. Complex body organisation and differentiation are seen.
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10.The five classes of vertebrates are Pisces, Amphibia, Reptilia, Aves and Mammalia.
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