4.2. Animal Development

Question 1

describes the changes in an organism from
its earliest beginnings through
maturity.

Answer 1

Development

Question 2

______is
the initial event in development in sexual reproduction.
Union of male and female gametes.
Recombination of paternal and maternal genes.
Restoration of the diploid number (two sets of chromosomes).

Answer 2

Fertilization

Question 3

The diploid cell resulting from
fertilization is now
called a___.

Answer 3

zygote

Question 4

\_\_\_\_ rapid cell divisions following
fertilization.
Very little growth occurs while the cells
are dividing.
Each cell called a \_\_\_\_

Answer 4

Cleavage; blastomere

Question 5

– the name given to the solid
ball of cells that results from
cleavage.
First __ divisions.

Answer 5

Morula ;5-7

Question 6

As divisions continue, a fluid filled
cavity called ____ , forms within the
embryo.
 The resulting hollow ball of cells is now called a ____

Answer 6

blastocoel; blastula

Question 7

The morphogenetic process called ___ rearranges the cells of a
blastula into a three-layered (triploblastic) embryo, called a ____, that has a primitive gut (____).

Answer 7

gastrulation; gastrula ;archenteron

Question 8

The ____ is the first opening in
the embryo – the point of invagination
during gastrulation.
This will eventually become either the mouth or the anus.
 One end of the gut-tube or the other.
 The space that forms during this time is the primitive gut, the _____

Answer 8

blastopore; archenteron.

Question 9

The three tissue layers produced by

gastrulation are called _____.

Answer 9

embryonic germ layers

Question 10

The _____ forms the outer layer of
the gastrula.
 Outer surfaces, neural tissue

Answer 10

ectoderm

Question 11

The ____ lines the embryonic

digestive tract

Answer 11

endoderm

Question 12

The ____ partly fills the space
between the endoderm and ectoderm.
Muscles, reproductive system

Answer 12

mesoderm

Question 13

Gastrulation in a ____ produces an

embryo with a primitive gut (archenteron) and three germ layers.

Answer 13

sea urchin

Question 14

Result is again an embryo with gut & 3 germ layers.
 Gastrulation in ___ is more complicated due to the moderate amount of yolk present in the egg.
 Blastula wall more than one cell thick.

Answer 14

the frog;

Question 15

Gastrulation in ___ is affected by the large amounts of yolk in the egg.
 Embryo essentially sits on top of large mass of yolk.

Answer 15

the chick

Question 16

– a groove on the surface along the
future anterior-posterior axis.
 Functionally equivalent to blastopore lip in frog.

Answer 16

Primitive streak

Question 17

In mammals the blastula is called a ___.
 ____ will become the embryo
while ___ becomes part of the
placenta.

Answer 17

blastocyst; Inner cell mass; trophoblast

Question 18

Gastrulation in ___ involves the
inner cell mass and is similar to that of
the chick due to the fact that
mammalian ancestors and early
mammals laid eggs.
 The large mass of yolk may be gone, but
the developmental pattern remains.

Answer 18

mammals

Question 19

Shortly after fertilization, the zygote undergoes a series of rapid cell divisions. This is called ___

Answer 19

cleavage

Question 20

During cleavage, each cell in the embryo is called a

Answer 20

blastomere

Question 21

The solid ball of cells that results from

cleavage is called

Answer 21

Morula

Question 22

A fluid filled space called the
blastocoel forms inside the
embryo - at this point it is a

Answer 22

blastula

Question 23

The stage that results in three
germ layers and a primitive gut is
the

Answer 23

gastrula

Question 24

The difference in gastrulation
found in different types of animals
is due primarily to:

a. The amount of yolk present
b. The size of the blastomeres
c. Development in different
species is completely
unrelated

Answer 24

a.The amount of yolk present

Question 25

Two major groups of triploblastic animals:
 \_\_\_\_\_ include flatworms, annelids and
molluscs.
\_\_\_\_\_ include echinoderms and
chordates.

Answer 25

Protostomes; Deuterostomes

Question 26

____ cleavage –occurs in most protostomes.

____ cleavage – is found in most deuterostomes.

Answer 26

Spiral; Radial

Question 27

– cell fate is determined by the components of the cytoplasm found in each blastomere.
 An isolated blastomere can’t develop.
 Protostomes

Answer 27

Mosaic development

Question 28

– the fate of a cell depends on its interactions with neighbors, not what piece of cytoplasm it has.
 A blastomere isolated early in cleavage is able to from a whole individual (e.g. twins).
 Deuterostomes

Answer 28

Regulative development

Question 29

_______ means “first mouth” while ____ means second mouth

Answer 29

Protostome; deuterostome

Question 30

In ___, the ____becomes the mouth. The second opening will become the anus.
while In ___,The __ becomes the anus and the mouth develops as the
second opening.

Answer 30

Protostome-blastopore; deuterostome-blastopore

Question 31

The ___ is a body cavity found in
many triploblastic organisms that is
completely surrounded by mesoderm.

Answer 31

coelom

Question 32

Not all ____ have a true coelom.

Answer 32

protostomes

Question 33

_____ have a body cavity between mesoderm and endoderm.
_____ have no body cavity at all
other than the gut.

Answer 33

Pseudocoelomates; Acoelomates

Question 34

In protostomes that have a coelom, a mesodermal band of tissue forms (before/after) the coelom is formed.

Answer 34

before

Question 35

In the process of
coelom formation called _____, this mesoderm splits to
form a coelom.

Answer 35

schizocoely

Question 36

In _____, the coelom forms as out pocketing of the gut.

Answer 36

enterocoely

Question 37

Typical ___ have coeloms that develop by enterocoely.

Answer 37

deuterostomes

Question 38

Radial cleavage is found primarily in

which group?

Answer 38

Deuterostome

Question 39

Early in cleavage, a blastomere becomes
isolated. It grows into an entire separate
individual. This is an example of __________
development found in ____________.

Answer 39

Regulative, deuterostomes

Question 40

The blastopore will become the mouth

in __

Answer 40

protostome

Question 41

“Coel” is a word-part that we see frequently. The
blastocoel is the space inside the blastula, the
coelom is a mesoderm-lined body cavity. What will
you find associated with “coel” words?

Answer 41

A cavity or space

Question 42

Most protostomes show this type of
coelom formation where a band of
mesoderm splits to form the coelom.

Answer 42

Schizocoely