Animal Body Plans and Evolution

Question 1

Bilateral Symmetry

Answer 1

body plan in which a single imaginary line can divide the body into left and right sides that are mirror images of each other

Question 2

Endoderm

Answer 2

innermost germ layer; develops into the linings of the digestive tract and much of the respiratory system

Question 3

Mesoderm

Answer 3

middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

Question 4

Ectoderm

Answer 4

outermost germ layer; produces sense organs, nerves and outer layer of skin

Question 5

Coelom

Answer 5

body cavity lined with mesoderm

Question 6

Pseudocoelom

Answer 6

body cavity that is only partially lined with mesoderm

Question 7

Zygote

Answer 7

fertilized egg

Question 8

Blastula

Answer 8

hollow ball of cells that develops when a zygote undergoes a series of cell divisions

Question 9

Protostome

Answer 9

an animal whose mouth is formed from the blastopore

Question 10

Deuterostome

Answer 10

group of animals in which the blastopore becomes and anus, and the mouth is formed from the second opening that develops

Question 11

Cephalization

Answer 11

concentration of sense organs and nerve cells at the anterior end of an animal

Question 12

Radial Symmetry

Answer 12

body plan in which any number of imaginary planes drawn through the center of the body could divide it into equal halves