CH32

Question 1

What is the order of apparition for animals, fungi and plants?

Answer 1

Animals first, fungi second, plants third

Question 2

Define

Animal

Answer 2

• Multicellular
• Heterotrophic
• Eukaryotes
• Developed tissues from embryonic layers (blastula)
• No cell walls but rather multicellular mobile tissues and multiple lifestages

Question 3

Describe

The reproduction and development of animals

Answer 3

• Sexual reproduction, diploidy dominate their life cycles
• Cleavage of zygote: blastula surrounds blastocel
• Gastrulation: layers of embryonic tissues that will develop into adult body parts (creation of gastrula)

Question 4

Define

Larva

Answer 4

Sexually immatude form of an animal, morphologically distinct from an adult, eats different food and may even have different habitat. Metamorhposes to juvenile

Question 5

Define

Homeoboxes

Answer 5

Developmental genes encoding transcriptions factors that regulate expression of other genes; contains sets of sequences called homeoboxes, such as the Hox genes

Question 6

What occurred during the Paleozoic Era?

Answer 6

Occurred 542-251 mya, scene of the Cambrian explosion and appearance of first arthropods.
During the Cambrian explosion, half of the present 36 phylas appeared due to the evolution of novel traits, a 2nd oxygen event that allowed for bigger sizes and the evolution of homeoboxes.

Question 7

Describe

Classification by symmetry

Answer 7

Radial symmetry vs bilateral symmetry

Question 8

Describe

Tissues

Answer 8

Result from the formations of layers called germ layers during gastrulation.
Ectoderm, Endoderm and Mesoderm (those who possess all three are called triploblastic)

Question 9

Define

Ectoderm

Answer 9

Surface of embryo, becomes outer covering of animals or nervous system.

Question 10

Define

Endoderm

Answer 10

Innermost layer, lines pouch that forms during gastrulation (archenteron) and gives rise to digestive tract lining/organs

Question 11

Define

Mesoderm

Answer 11

Third layer of tissues possessed by bilaterally symmetrical animals, between ecto and endoderm. Forms muscles and organs between digestive tract and outer covering.

Question 12

Describe

Body cavities

Answer 12

Fluid/air-filled space also called coelom (true ones derived from mesoderm; those who possess it are called coelomates) Those who have an mesoderm+endoderm coelom are called pseudocoelomates and those who don’t have it are acoelomates

Question 13

Define

Grade

Answer 13

Groups that share biological traits not derived from the same ancestor

Question 14

What are the advantages provided by the coelom?

Answer 14

Provides cushion, frame for muscles to work against, allow internal organs to move/grow independent from outer body wall

Question 15

What are the two modes of development of animals?

Answer 15

Proteostomes and deuterostomes

Question 16

What are the differences between proteostomes and deuterostomes?

Answer 16

• Proteostome: spiral, determinate cleavage of zygote
• Coelom formation begins in gastrula stage, coelom forms from split in mesoderm (proteostome); forms from mesodermal outpocketings in deuterostomes
• Mouth forms from blastopore in proteostome; anus forms from blastopore in deuterostome

Question 17

What are some facts about animals?

Answer 17

• All animals share a common ancestor (Metazoa clade)
• Sponges are basal animals, first to branch out
• Eumetazoa is a clade of animals with true tissues
• Most animals belong to Bilateria clade (bilateral symmetry + triploblastic)
• Bilateria is divided into 3 clades: deuterostomia, lophotrochozoa, ecdysozoa

Question 18

What are the features of the three Bilateria clades?

Answer 18

• Deuterostomia: deuterostome development
• Ecdysozoa: secretion of exoskeletons, shedding referred to as ecdysis
• Lophotrochozoa: lophophores, ciliated feeding tentacles and trochopore larva stage.