Lecture 4: Life History 1

Question 1

Ontogeny

Answer 1

Embryonic development from fertilization to birth

Question 2

Oviparous

Answer 2

Egg birth

Question 3

Viviparous

Answer 3

Live birth

Question 4

Maturation

Answer 4

Developmental changes that take place from birth (hatching) until sexual maturity

Question 5

Metamorphosis

Answer 5

An abrupt change in body features that takes place after birth (hatching) to the mature form (tadpole to frog)

Question 6

Senescence

Answer 6

Aging; loss of physical vigor and reproductive ability

Question 7

Fertilization

Answer 7

Union of male and female gametes, setting in motion a complex series of developmental events that ultimately leads to the formation of an embryo

Question 8

Events in fertilization?

Answer 8

1. Sperm pro-nucleus enters egg; pro-nuclei migrate toward each other
2. Sperm chromatin activates
3. Nuclear membranes break down; new nuclear membrane forms around egg and sperm chromosomes 4. Fertilization complete; cleavage (nuclear division) begins

Question 9

Morula

Answer 9

8 cell stage of cleavage

Question 10

Blastula

Answer 10

Hollow sphere of cells

Question 11

How are cleavage patterns determined?

Answer 11

By the amount of yolk and the extent to which the yolk divides.

Question 12

Holoblastic

Answer 12

Complete yolk division

Question 13

Meroblastic

Answer 13

Incomplete yolk division

Question 14

Cleavage pattern of amphioxus?

Answer 14

Holoblastic, microlethical (small amt of yolk)

Question 15

Cleavage pattern of amphibians?

Answer 15

Holoblastic, mesolethical (middle amt of yolk)

Question 16

Cleavage pattern of reptiles/birds?

Answer 16

Discoidal, macrolethical (abundant amt of yolk)

Question 17

Cleavage patterns of mammals?

Answer 17

Holoblastic, microlethical (small amt of yolk)

Question 18

Cleavage pattern of fish?

Answer 18

Meroblastic, macrolethical (abundant amt of yolk)

Question 19

Gastrulation

Answer 19

Formation of the archenteron (primitive gut) via invagination of endodermal cells

Question 20

Neurulation

Answer 20

Formation of neural tube through folding of a special portion of dorsal ectoderm (neural plate)

Question 21

Epiboly

Answer 21

Spread of cells across the embryo surface (exterior)

Question 22

Involution

Answer 22

Cells migrate inward and spread across an internal surface

Question 23

Invagination

Answer 23

Cells indent or fold inward. Forms the blastopore.

Question 24

Protostomes

Answer 24

Means “first mouth”, blastopore formed by invagination forms the mouth of the animal, anus forms where archenteron meets the ectoderm.

Question 25

Deuterostome

Answer 25

Means “second mouth”, blastopore formed by invagination forms the anus of the animal, mouth forms where archenteron meets the ectoderm.
Chordates are deuterostomes

Question 26

Outcomes of gastrulation?

Answer 26

1. Three primary germ layers are established (endoderm, mesoderm, ectoderm)
2. Basic body plan is established
3. Cells are brought into new positions, allowing for the inductive interactions that help with organogenesis and neurulation

Question 27

What does the neural tube form?

Answer 27

The CNS (brain and spinal chord)

Question 28

Somites

Answer 28

Aggregates of mesoderm cells that ultimately give rise to muscle structures

• skin (dermatome)
• body musculature (myotome)
• vertebrate (sclerotome)

Question 29

Tissue

Answer 29

Group of cells that perform a function (histiogenesis)

Question 30

Organ

Answer 30

Group of tissues that perform a function (organogenesis)