Chapter 32

Front 1

List five criteria, taken together, comprise a reasonable definition of an animal.

Back 1

1. Animals are multicellular, ingestive heterotrophs
2. Animal cells lack cell walls that provide structural support for plants and fungi
3. Animals have two unique types of cells: nerve cells for impulse conduction and muscle cells for movement.
4. Most animals reproduce sexually, with the diploid stage usually dominating the life cycle
5. Animals share a unique homeobox-containing family of genes known as Hox genes

Front 2

The zygote undergoes _____
a succession of mitotic cell divisions, leading to the formation of a multicellular, hollow ball of cells called the _______.

Back 2

cleavage,
blastula

Front 3

During _______ part of the embryo folds inward, forming layers of embryonic tissues that will develop into adult body parts.  The resulting development stage is called a ______.

Back 3

gastrulation, gastrula

Front 4

Some animals develop directly through transient stages into adults, but others have ________________.

Back 4

distinct larval stage or stages

Front 5

A _____ is a sexually immature stage that is morphologically distinct from the adult, usually eats different foods, and may live in a different habitat from the adult

Back 5

larva

Front 6

Animal larvae eventually undergo _____ transforming the animal into an adult.

Back 6

metamorphosis

Front 7

Many of these regulatory genes contain common modules of DNA sequences called _____.

Back 7

homeoboxes

Front 8

All animals share the unique family of Hox genes, suggesting that __________.

Back 8

this gene family arose in the eukaryotic lineage that gave rise to animals