Topic 20

Question 1

Animal’s Protist Ancestor

Answer 1

Choanoflagellate protists

-flagellated eukaryotes, small, unicellular, heterotrophic

Similarities in Cell morphology, DNA sequence homology and unique cell traits only in animals

Question 2

Evolution of Multicellularity

Answer 2

Independent evolution in mutiple lineages

Question 3

Benefits of Multicellularity

Answer 3

• cell specialization
• increased size/complexity
• longer lifespans
• enhanced defence against predation

Question 4

Significance of Cambrian Explosion

Answer 4

Significant diversification of bilateral animal evoltuon

• Evolution of predation
• Neoproterozoic Oxygenation Event
• Evolution of Hox gens (control the body plan of animals)

Question 5

Invertebrate Diversity

Answer 5

95% of known animal species that can be microscopic to giants

Anatomical classification of having no backbone and is paraphyletic

NOT A CLADE

Clades: Metazoa, Eumetazoa, and Bilateria