BSC2011 - chapter 33

Animals with radial symmetry have ___germ layers, and animals with bilateral symmetry have ___germ layers.

2, 3

What is a hydrostatic skeleton?

A fluid-filled body cavity surrounded by muscle that provides shape and support to the body

Which is a blastula?

A hollow sphere of cells produced early in the development of an animal embryo

Scientists now believe, supported by molecular evidence, that the presence or absence of a(n)___ or a(n) ____is not sufficient to construct animal phylogenies.

Blank 1: coelem or coelom Blank 2: pseudocoelem or pseudocoelom

In the figure of a gastrula, the germ layer represented by A is the___ , B is the ___, and C is the___

Blank 1: endoderm Blank 2: ectoderm Blank 3: mesoderm

Which of these animal groups exhibit radial symmetry?

Cnidarians

Animals can be classified based on the development of a body cavity. Match each type of animal with the correct definition.

Coelomate: Animal with a fluid-filled body cavity lined with tissue from the mesoderm. Acoelomate: Animal that lacks a fluid-filled body cavity. Pseudocoelomate: Animal with a body cavity not completely lined with tissue from the mesoderm.

Characteristic features of protostome development include which of the following?

Determinate cleavage The blastopore becomes the mouth.

What happens during gastrulation?

Different cell layers are produced in a developing embryo.

All animals belong to the domain

Eukarya

What are Hox genes?

Genes responsible for pattern formation of the body and appendages in early embryos

Animals that would be placed in the group Bilateria include which of the following?

Horse Spider Lobster

What is an advantage of segmentation?

It allows for specialization of body regions.

What are germ layers?

Layers of cells in an embryo that form the organs

Which of the following include features traditionally used by biologists to classify animal diversity?

Number of germ layers Type of body symmetry Features of embryonic development

What is the posterior end of the body?

The back or rear

Which of the following is true of deuterostomes?

The blastopore develops into the anus.

What statement about the endoderm and ectoderm is correct?

The ectoderm differentiates into the nervous system and epidermis, while the endoderm lines the digestive tract.

How do traditional and contemporary phylogeneticists view the use of body cavity in animal classification?

Traditional phylogeny used the presence or absence of a body cavity; molecular phylogeny suggests this is not a useful method of classification.

The fluid in the body cavity of an animal can

assist with movement, act as a circulatory system, and provide shape

Most animals are ___symmetric.

bilateral

In the animal kingdom, the majority of species are

bilaterally symmetric

Animals that are bilaterally symmetrical are placed in the group___

bilateria

The closest living relatives of animals are the

choanoflagellates

Advantages of a body cavity include

cushioning internal organs enabling movement and growth of internal organs independently of the outer body wall acting as a rudimentary circulatory system providing support and shape to an organism

In______, the blastopore becomes the anus, and the mouth is formed from a secondary opening.

deuterostomes

The three embryonic germ layers are called

endoderm, ectoderm, mesoderm

The use of molecular data to construct phylogenetic trees is based on the premise that more closely related species exhibit ___sequence differences than distantly related ones.

fewer

Embryonic cell layers are called

germ layers

Genes involved in pattern formation of the body and appendages in early embryos are

hox genes

Ventral typically refers to the

lower side of an animal's body

The gene that encodes the small subunit of ribosomal RNA is often used for

molecular phylogenetic analysis

Ectoderm is essential in the formation of the

nervous system epidermis

With regard to phylogenetic trees based on morphological data and molecular data,

phylogenies based on molecular data tend to be more accurate

Some animals are not generally thought to possess specialized tissue types or organs, although they may have several distinct types of cells. These animals are members of the phylum___

porifera

The back or rear of the body is called the___ end.

posterior

Cnidarians (jellyfish and coral) are ___symmetric animals.

radial

When an animal's body is divided into a number of nearly identical units or regions, it has a(n) Blank______ body plan.

segmented

A major difference in embryo development between sponges and other animals is

sponge embryos do not develop germ layers

Based on recent studies of molecular phylogeny, scientists suggest that

the Protostomes are divided into two clades, the Ecdysozoa and Lophotrochozoa

Dorsal refers to the

upper side of an animal's body.

The underside or lower surface of the body is called the ______ side. Multiple choice question.

ventral