Page 9 - Science Course 2 (Book 1)

Animals and Their Characteristics Mo1-L1a: How are Animals Classified?
Lesson 1

Asymmetry

a body plan in which an organism cannot be divided
In this topic, you will learn the following into any two parts that are nearly mirror images.
lessons:

Mo.1-L1a: How are Animals Classified?
Mo.1-L1b: How Do Animals Adapt To Their
Environment?

Mo1-L1a How are Animals Classified?

KEY CONCEPTS: Let’s Begin
1. What characteristics are common to all animals?
2. How do scientists group animals?
Animal Characteristics

Vocabulary A-Z • All animals, like plants, are multicellular.

Let us learn some vocabulary • Animals are the only living things that have nerve
cells which conduct nerve impulses.

• All animals get energy from the food they take into
Bilateral symmetry
their bodies.
a body plan in which an organism can be divided
into two parts that are nearly mirror images of each
other.

Radial symmetry

a body plan in which an organism can be divided into All animals begin as a fertilized egg cell called a
two parts that are nearly mirror images of each other zygote, which divides into more cells and forms an
anywhere through its central axis. embryo.

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