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SS1: BIOLOGY - 1ST TERM

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  1. Introduction to Biology | Week 1
    6 Topics
    |
    1 Quiz
  2. Recognizing Living Things | Week 2
    3 Topics
    |
    1 Quiz
  3. Organisation of Life | Week 3
    3 Topics
  4. Classification of Living Organisms | Week 4
    7 Topics
    |
    1 Quiz
  5. Kingdom Prokaryotae / Monera & Kingdom Protista | Week 5
    3 Topics
    |
    3 Quizzes
  6. Kingdom Fungi & Kingdom Plantae | Week 6
    9 Topics
    |
    2 Quizzes
  7. Kingdom Animalia I | Week 7
    6 Topics
    |
    1 Quiz
  8. Kingdom Animalia II | Week 8
    5 Topics
    |
    1 Quiz
  9. The Cell | Week 9
    3 Topics
    |
    1 Quiz
  10. The Cell Structure and Functions | Week 10
    4 Topics
    |
    1 Quiz
  11. The Cell and its Environment | Week 11
    4 Topics
    |
    1 Quiz
  12. Nutrition in Plants | Week 12
    4 Topics
    |
    1 Quiz



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corals
Corals (Phylum Coelenterata)

Characteristics of Phylum Coelenterata:  

1. They are mostly aquatic organisms. 

2. They are diploblastic organisms i.e they have two distinct body layers (ectoderm and endoderm) separated by a mesogloea.

3. They exhibit tissue level of organization.

4. They are radially symmetrical

5. They have only one body cavity called enteron or gut (gastrovascular cavity) with only one opening, the mouth, and no anus. The mouth also serves as an anus.

6. They have tentacles surrounding the mouth. 

7. They also possess stinging cells called nematocysts, found on the tentacles, used for capturing their prey.

8. Digestion is both intracellular and extracellular.

9. They lack nervous and circulatory systems.

10. They reproduce asexually through budding. Sexually, they are hermaphrodites. The sexual mode of reproduction is seen only in a few Coelenterates.

11. They exhibit polymorphism i.e. they exist in two structural forms, polyp and medusa. The medusa is umbrella-shaped and motile e.g. Jellyfish, while the polyp is cylindrical and sessile e.g. Hydra and Sea-anemone.

12. The polyp and the medusa may alternate in the life cycle of some Coelenterates (Cnidarians).

Coelenterata
Coelenterata body forms. Cnidarians have two distinct body plans, the medusa and the polyp. All cnidarians have two membrane layers, with a jelly-like mesoglea between them.

Cross section of a Hydra Polyp.
Cross section of a Hydra Polyp.

13. Live in colonies (corals) as well as solitary (Sea anemone).

cover14
Coral reefs are made up of colonies of coral polyps held together by calcium carbonate.

14. Examples of Phylum Coelenterata are Hydra, Obelia, Jellyfish, Sea anemone, and corals.

Classification of Phylum Coelenterata:

Coelenterates are classified into three different classes:

a. Hydrozoa e.g. Hydra
b. Scyphozoa e.g. Jellyfish
c. Anthozoa e.g. Sea Anemone

hydra
Hydra.
Phylum Coelenterata jellyfish
Jellyfish.
Sea anemone
Sea anemone.

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