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Question 1

List the main distinguishing features of the kingdom Animalia and recognise the features that are used in the phylogeny of modern groups of animals

Answer 1

Multicellular
Animal cell have no cell walls
Heterotrophic
Reproduction commonly done sexually
Animals at some point are mobile
Responds rapidly to external stimuli
Calcification done through bilateral or radial symmetry
And if they hold no issue, they are sponges.

Question 2

Distinguish between radial and bilateral symmetry, and give examples of phyla (and representative organisms) that display each of these types of symmetry

Answer 2

Radial - symmetry is placed four ways and the embryo hold 2 germ layers, end/ectoderm: Phylum Cnidarian (sea jellies, anemones, coral) and Phylum Ctenophora (comb jellies)
Bilateral - place of symmetry is split two ways and embryos hold 3 germ layers, endo/ecto/mesoderm: all other invertebrates.

Question 3

Describe the differences among animals characterised as coelomates, pseudocoelomates, or acoelomates, and describe the main differences between the protostome mode of development and the deuterostome mode of development

Answer 3

Coelomates - digestive tract is in a cavity lined completely with mesoderm
Pseudocoelomates - body cavity is partially lined with mesoderm
Acoelomates - no separation between body wall and digestive tract
Protostome development - ‘first mouth’ invagination at gastrula stage becomes the mouth: includes roundworms, flatworms, segmented worms, molluscs, and arthropods
Deuterostome development - ‘second mouth’ invagination of gastrula becomes the anus; mouth forms secondarily: includes echinoderms and chordates

Question 4

Describe the main distinguishing features of the phylum Platyhelminthes

Answer 4

Commonly known as flatworms
Free-living or parasitic
The parasitic are two major groups (cestodes- tapeworms and trematodes - trematodes) they require primary host (digestive tracts) and secondary hosts (vertebrate or mollusc).
Reproduce asexually (regeneration of body) or sexually
Most are hermaphroditic, and can self-fertilise
Possess simple tissues: eyespots, ganglia, nerve cord
No circulatory or respiratory systems

Question 5

Describe the main distinguishing features of the phylum Arthropoda, outline the main advantages and disadvantages of the arthropod exoskeleton

Answer 5

Differences - they hold an exoskeleton that is shed periodically. A segmented body with paired jointed appendages
Special adaptations - cuticles that prevent water loss, wings for insects and the body: head (sensory apparatus and feeding), Thorax (locomotion) and abdomen (digestion and reproduction).
Advantages - protection, watertight and provides a rigid attachment site for muscle however joints are thin and flexible.
Disadvantages - moulting can be dangerous as they are left vulnerable and it requires a lot of energy, the exoskeleton is also heavy