Question

Chapter 32: Overview of Animal Diversity 1. Like the fungi, animals are multicellular heterotrophs. How do they feed? 2. What two types of specialized cells do only animals have? 3. Most animals reproduce and the stage dominates the life cycle. 4. What is animal Development? 5. Define/describe each term: zygote: cleavage: blastula: gastrulation: gastrula: blastopore: metamorphosis: 7. All eukaryotes have sets of regulatory genes containing common sets of DNA sequences called homeoboxes. What are the unique homeobox genes of animals called? 8. Sponges lack symmetry, but two types of symmetry are seen in all other animal groups. Name and describe them in words or with a sketch. 9. What is the symmetry of a jellyfish? of a worm? of a dog? 10. Animals that have bilateral symmetry have a front and rear. Draw a sketch of a cat, and label these regions: anterior, posterior, dorsal, and ventral 11. Many animals with radial symmetry are sessile. What does this mean?

Answer 1

1. Heterotrophs are organisms that cannot prepare their own food and depend on other organisms for their food.

Animals are heterotrophs as they obtain their food from plants or other animals. Plants prepare food through photosynthesis and store it as starch in their fruits, stem, roots and other parts, which are ingested by animals. Some animals (carnivores) feed on other animals, while some (parasites) live inside other animals and feed on them.

2. There are several types of specialized cells found only in animals. Examples of such cells include blood cells, muscular cells, skeletal cells.

3. Most animals reproduce sexually and the diploid stage dominates the life cycle.

Two parents are involved in sexual reproduction while the dominant stage involves diploid stage wherein most of the cells have "2n" no. of chromosomes, with only sex cells being an exception which has "n" no. of chromosomes. For example, only sex cells in humans have 23 chromosomes while all other cells have 46 chromosomes.

4. The process by which an entire organism is formed from a single-celled zygote by repeated mitotic division is known as animal development.

5.

a. zygote - single diploid cell formed by the fusion of male and female sex cells during fertilization. The male sex cells are known as sperms and the female sex cells are known as ova or eggs.

b. Cleavage - The repeated mitotic zygote leading to the formation of a multicellular blastula is known as cleavage.

c. Blastula - The repeated mitotic division of cells of zygote leads to the formation of a multicellular hollow sphere known as blastula.

d. gastrula - The rearrangement of blastular cells leads to the formation of three germ layers namely endoderm, ectoderm and mesoderm. This hollow structure having three germ layers is known as gastrula.

e. Gastrulation - This known as gastrulation.e process of rearrangement of blastular cells leading to the formation of three germ cells.

f. Blastopore - A tiny opening in the embryo that helps it to interact with the outside environment for its life processes.

g. metamorphosis - The process by which drastic changes leads to the formation of adult from a very distinct larva. For example - Butterfly developing from a pupa as both are very physically distinct.