Some examples from this set of practice questions
1.
What organism falls under the phylum porifera, and describe the 3 distinct groups within this phylum (7 marks).
Answer: Organism is sponges. The 3 distinct groups are: 1. Hexactinellid – glass sponges 2. Demospongiae – cartilaginous sponges 3. Calcarea – calcareous sponges
2.
Using a labelled diagram show the typical cross section of a poriferan (10 marks).
Answer: The diagram must be drawn neatly, with label lines ending at the same point and none criss-crossing each other (1 mark). The drawing must include the following labels (9 marks): - Osculum - Pinacocytes - Gelatinous matrix - Spicules - Water flowing in through the pores - Collar Cell showing: - Flagella - Choanocyte - Amoebocyte
3.
List and explain the 3 types of body structures sponges can have (6 marks).
Answer: 1. Asconoid sponges - they have a simply tube shape. 2. Synconoid sponges - they have a slightly more complex tube shape with simple canals between the pores. 3. Leuconoid sponges - these are the largest and most complex sponges, with multiple canals and chambers within the tissue of the sponge.
4.
What are the particles called which make up a sponges skeleton, and what are the 3 different groups of these particles (based on what they\'re made from)? (4 marks)
Answer: The particles are called spicules, and they can be calcareous, siliceous, or made from spongin.
5.
Where does the name \'Cnidaria\' come from and what does it mean? (2 marks)
Answer: Cnidaria is a Latin word, derived from the term for \'stinging cells\'.
6.
Provide 5 characteristics of the phylum Cnidaria. (5 marks)
Answer: 1. They are bell-shaped/tubular animals 2. Their body has layers: - Outer protective epidermis - Mesoglea - Gastrodermis - Inner endoderm layer – secretes juices and enzymes directly into gastrovascular cavity (GVC). 3. They possess radial symmetry 4. Their mouth is surrounded by tentacles connected to GVC. 5. They have no circulatory, respiratory, or excretory organs. 6. Reproduction has two phases = sexual budding (polyps) and sexual reproduction (medusa). 7. All are aquatic – mostly marine species. 8. They have 2 basic body forms during their life cycle: - Polyps – mouth directed upwards, tubular/flower-like, sessile. - Medusa – mouth directed downwards, jellyfish/umbrella shape, mobile. 9. Muscle fibres & nerve fibres can contract and expand which results in directional movement. 10. Polyps are sessile (stay in one place) = e.g. sea anemones 11. Medusas are mobile (float or swim in a water column) = e.g. jellyfish 12. Tentacles form a ring around the mouth & can reach out and grasp prey that has been stung by cnidocytes. 13. Gaseous exchange occurs directly across the body surface. 14. Waste is released either through gastrovascular cavity (GVC) or through the skin.
7.
Draw a labelled diagram showing the structure of a cnidocyte (8 marks).
Answer: The drawing should be neat with the label lines ending at the same point (1 mark). The labels must include the following (7 marks): - Nematocysts - Unfired stinging cell - Trigger hair - Open lid to stinging cell - Fired stinging cell - Barb - Nematocs
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