Topic 20: Origin Of Animals

Question 1

What do ancestoral protists likely resemble?

Answer 1

This ancestral protist likely resembled modern
choanoflagellates, which are flagellated eukaryotes.

Question 2

Choanoflagellates are _________ protists that are the closests relatives to animals

Answer 2

Opisthokont

Question 3

Basal chaonoflagellates are ___, _____, and _____

Answer 3

Small, unicellular, and heterotrophic

Question 4

How would you describe a chaonoflagellate?

Answer 4

They are collared flagellates with a funnel-shaped collar/microvilli at the base of the flagellum

Question 5

What are microvilli?

Answer 5

re finger-like projections of the
cell membrane that captured bacteria.

Question 6

What are animals hypothesized to evolve from?

Answer 6

Choanoflagellate-like ancestors

Question 7

What are the three pieces of evidence that choanoflagellates closely resemble animals?

Answer 7

1) cell morphology
2) animals have a unique cell morphology
3) homolous DNA sequence

Question 8

Did multicellularity evolve dependantly or independantly in many lineages?

Answer 8

Independantly

Question 9

What are some evolutionary advantages to bein multicellular?

Answer 9

• the bigger you are, the harder is is to get eaten
• cell specialization
• more complexity and size
• long life span
• least predators on you

Question 10

What era where multicellular animal fossils come from?

Answer 10

Ediacaran biota era

Question 11

What are ediacaran biota?

Answer 11

Diverse, soft-bodied and non-motile marine organisms that have radial symmetry

Question 12

Event that klet to a significat diversification of animal evolution

Answer 12

Cambrian explosion

Question 13

What do the fossils from the cambrian explosion show

Answer 13

It showed a rapid evolution and increase of diversity of various bilaterian animals
(Most animals had a fossil from this era)

Question 14

What are three hypothesis for the cambrian explosion

Answer 14

• evolution of predation: lead to more complex body structures
• oxygenation event: more oxygen suppotd greater body sizes and energtic lifestyles
• evolution of hox genes: facilitates in the diversification of complex body forms

Question 15

Three eras of animal evolution

Answer 15

• paleozoic
• mesozoic
• cenozoic

Question 16

What does the term invertebrates refer to?

Answer 16

An animal without a backbone

Question 17

Are invertebrates monophyletic, para or polyphyletic?

Answer 17

Paraphyletic

Question 18

What is the most critical era where mammals increased in size and diversity after the cretaceous mass extinction?

Answer 18

Cenozoic era

Question 19

what are hypothesiss for the cambriage explosionÉ

Answer 19

evolution of predation, the great oxigenation event and the evolution of hox genes