EasyBiologyHigh School (11–12)Diversity of Living Organisms › Basis of Animal ClassificationConceptualBoard Exam
Ritu describes four animals from a pond…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Ritu describes four animals from a pond.
- A sponge whose cells form loose groups, with some cells doing special jobs.
- A Hydra, whose cells form true tissues but no organs.
- A flatworm with tissues grouped into organs.
- A water snail whose organs work together in systems.
Give the level of organisation of each.
Need a reminder? The key ideaShow
Levels of organisation: cellular (Porifera), tissue (coelenterates), organ (Platyhelminthes), organ system (annelids, arthropods, molluscs, echinoderms, chordates). An incomplete gut has one opening; a complete gut has a mouth and an anus. Open circulation bathes the tissues in blood (arthropods, molluscs); closed circulation keeps it in vessels (annelids, chordates). Symmetry: asymmetrical, radial or bilateral.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Loose groups of cells with no true tissues: the cellular level.
Step 2. (b) Tissues but no organs: the tissue level.
Step 3. (c) Tissues grouped into organs: the organ level.
Step 4. (d) Organs working in systems: the organ system level.
Answer: (a) cellular; (b) tissue; (c) organ; (d) organ system.
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