Animal Diversity and Development

Question 1

What did animals evolve from?

Answer 1

A single celled protist

Question 2

What is the closest living relative to Animals?

Answer 2

Choanoflagellates through morphological and molecular evidence
They showed colonial behavior which led to multicellular common ancestry

Question 3

What are animals?

Answer 3

multicellular, heterotrophic eukaryotes with tissues developing from embryonic layers

Question 4

What is the nutritional mode of the animal kingdom?

Answer 4

Chemoheterotrophs that ingest food
cannot construct their own organic molecules like plants can
do not feed by absorption of material
ingest food then use enzymes to digest it within their bodies

Question 5

What type of genes to animals have, exclusively?

Answer 5

HOX genes which regulate development

Question 6

Describe the development of animals.

Answer 6

Most animals reproduce sexually with the diploid stage
sperm and egg fuse to make a zygote
the zygote undergoes cleavage (rapid cell divisions)
Leads to formation of hollow balls, Blastula with a fluid center called the blastocoel
tissue formation though gastrulate

Question 7

What is gastrulation?

Answer 7

cells migrate and fold into the blastocoel, forming the ectoderm, endoderm, and mesoderm

Question 8

What is a blastopore?

Answer 8

where the digestive space, called the archenteron opens to outside

Question 9

What are the four body plan characteristics?

Answer 9

symmetry
tissue layer
body cavity
embryonic development

Question 10

What are the references for bilateral symmetry?

Answer 10

Dorsal: Top
Ventral: Bottom
Posterior: Back
Anterior: Front

Question 11

What are the three true layers

Answer 11

Ectoderm: forms the outer layers, like skin and neurons
Endoderm: forms archenteron and digestive tissues
Mesoderm: forms muscles and skeleton

Question 12

What is a diploblast?

Answer 12

animals with two tissue layers, the ectoderm and endoderm

Question 13

What is a triploblast?

Answer 13

animals with all three layers

Question 14

What is the body cavity used for?

Answer 14

allows for growth
cushion for internal organs
pressure-resistance in organism lacking rigid skeleton structures

Question 15

What is the main difference between protostomes and deuterostomes?

Answer 15

Protostomes: cleavage is spiral and determinate
Deuterostomes: cleavage is radial and indeterminate

Question 16

How is the coelom formation from Mesoderm different?

Answer 16

Protostomes: solid mass of mesoderm splits inside to make body cavity
Deuterostomes: layers of mesoderm pinch together

Question 17

How does the blastopore differ?

Answer 17

Protostomes: mouth forms first
Deuterostomes: anus forms first

Question 18

What happened during the Cambrian Period?

Answer 18

the Cambrian explosion brought a wave of animal diversification during the Paleozoic Era
Appearance of arthropods, chordates, and echinoderms with characteristics like mineralized shells, toothpick spikes, and grasping limbs

Question 19

What happened during the Mesozoic Era?

Answer 19

coral reefs emerged
dinosaurs were dominant
first non-arthropod wings evolved
mammals first appeared

Question 20

What was the KT Event?

Answer 20

Extinction Event that marks the Cretaceous-Tertiary Boundary

Question 21

Describe the Cenozoic Era.

Answer 21

Begins with extinctions of terrestrial and marine animals

diversification of mammal orders and insects