Introduction to animals

Question 1

What defines animals?

Answer 1

Multicellular heterotrophic eukaryotes that ingest food, lack cell walls, have nerves/muscles, and reproduce sexually

Question 2

What key structures and features do most animals have?

Answer 2

Nervous and muscular systems, extracellular matrix, unique cell junctions, and Hox genes.

Question 3

What are Hox genes?

Answer 3

Regulatory genes containing a homeobox DNA sequence; control body plan and segment identity along the anteroposterior axis.

Question 4

Why are Hox genes important evolutionarily?

Answer 4

They enabled development of complex structures (e.g., heads, brains, limbs, vertebrae) through segment specialisation

Question 5

Difference between protozoa and metazoa?

Answer 5

Protozoa are unicellular; Metazoa are multicellular animals.

Question 6

What is the role of Hox genes in higher animals?

Answer 6

Control expression cascades for body region identity; multiple Hox complexes allow greater developmental complexity.

Question 7

How many phyla are in the animal kingdom?

Answer 7

Around 35–37 recognized phyla.

Question 8

Are animals monophyletic or polyphyletic?

Answer 8

Monophyletic — they evolved from a single common ancestor.

Question 9

What is the Linnaean system?

Answer 9

A binomial and hierarchical taxonomy system using genus and species names.