5. Development

Question 1

Importance of Developmental studies

Answer 1

Evidence for common descent

Helps with construction of phylogenies

Question 2

Ontogeny

Answer 2

Developmental history of an individual throughout its life

Question 3

Ernst Haeckel

Answer 3

“Ontogeny recapitulates phylogeny”

Suggested that the developmental stage represented the adult stage of its evolutionary history

Question 4

Key events in animal development

Answer 4

1. Gamete formation
2. Fertilization
3. Cleavage
4. Gastrulation
5. Organogenesis
6. Growth

Question 5

Egg

Answer 5

An ovum

Question 6

Ovum

Answer 6

Female reproductive or germ cell

Question 7

Germ cell

Answer 7

Haploid cell whose fertilization by one of the opposite kind produces a diploid zygote

Question 8

Gamete

Answer 8

A mature haploid sex cell, egg or sperm

Question 9

Egg’s polarity

Answer 9

Animal Pole - Mostly cytoplasm

Vegetal Pole - Mostly yolk

Question 10

Isolecithal

Answer 10

Very little yolk
Evenly distributed
- Placental animals
- Echinoderms, tunicates, cephalochordates, molluscs

Question 11

Mesolecithal

Answer 11

Moderate amount of yolk concentrated at vegetal pole

- Amphibians

Question 12

Telolecithal

Answer 12

Abundance of yolk densely at vegetal pole

- Birds, reptiles, fish, monotremes, some amphibians

Question 13

Centrolecithal

Answer 13

Large centrally located mass of yolk

- Arthropods

Question 14

Development of telolecithal eggs

Answer 14

Egg to miniature adult

Question 15

Development of isolecithal/mesolecithal eggs

Answer 15

Larval stage capable of feeding itself
Metamorphosis to reach adult
- exceptions: mammals

Question 16

Holoblastic cleavage

Answer 16

Complete and approximately equal divisions of cells

- isolecithal, mesolecithal

Question 17

Meroblastic cleavage

Answer 17

Restricted to small area of egg

- Telolecithal, Centrolecithal

Question 18

Direction of cleavage

Answer 18

Spiral / Radial

Question 19

Gastrulation

Answer 19

Converts spherical blastula into two or three layered embryo

Question 20

Germ layers

Answer 20

Layers that form during gastrulation

Question 21

Gastrulation process

Answer 21

1. One side of the blastula bends inward in a process called invagination
2. Internal pouch formed is the gut cavity (archenteron or gastrocoel)
   * The opening to the gut cavity is the blastopore
3. A second opening forms, forming a gut tube
4. Third layer forms from endoderm

Question 22

Gut Cavity’s names

Answer 22

Archenteron, Gastrocoel

Question 23

Outer Layer of Blastula

Answer 23

Ectoderm

Question 24

Inner Layer of Blastula

Answer 24

Endoderm

Question 25

A gut opening only at blastopore is called

Answer 25

Blind Gut

Question 26

Mesoderm

Answer 26

The third layer between ectoderm and endoderm

Question 27

Coelom

Answer 27

Cavity completely surrounded by mesoderm

Question 28

Diploblastic

Answer 28

Having two germ layers

Question 29

Triploblastic

Answer 29

Having three germ layers

Question 30

Organogenesis

Answer 30

Development of organs from specific germ layers

Question 31

Nervous system development (Organogenesis)

Answer 31

From the ectoderm

Question 32

Heart development (Organogenesis)

Answer 32

Is the first functional organ
Formed from mesoderm
Starts beating at day 2 - For chicken

Question 33

Categorizing by Germ layers

Answer 33

Diploblastic

Triploblastic

Question 34

Categorizing by coelom

Answer 34

Acoelomate, pseudocoelomate, coelomate

Schizocoely, enterocoely

Question 35

Categorizing by cleavage pattern

Answer 35

radial, spiral

Question 36

Body symmetry

Answer 36

spherical, radial, bilateral

Question 37

Mechanism of development

Answer 37

Mosaic, regulative

Question 38

Types of categorizing

Answer 38

1. Number of germ layer
2. Coelom development
3. Cleavage pattern
4. Body symmetry
5. Mechanism of development