Download Introduction to Animals

Name
Class
Date
Introduction to
Animals
Unity and Diversity of Life
Q: What characteristics and traits define animals?
WHAT I KNOW
25.1 What is an
animal?
25.2 How
have different
animal body plans
evolved?
WHAT I LEARNED
SAMPLE ANSWER:
Animals are
different from other living
things (bacteria, protists,
fungi, and plants).
SAMPLE ANSWER: All animals are
multicellular, eukarytotic,
and heterotrophic. Their cells
lack cell walls. Chordates
exhibit four characteristics
during some stage of their
development: a dorsal,
hollow nerve cord; a
notochord; a tail that extends
beyond the anus; and
pharyngeal pouches.
SAMPLE ANSWER:
SAMPLE ANSWER:
Each animal
group evolved a group of
structures or “body plan”
that is unique to that group.
The features
of a body plan include
levels of organization
(cells, tissues, organs, organ
systems); body symmetry;
differentiation of germ
layers; formation of a cavity
between the digestive tract
and the body wall; patterns
of embryological development;
segmentation; cephalization;
and limb formation. The
features of body plans
provide evidence needed to
build a cladogram, or
phylogenetic tree, of animals.
Chapter 25 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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25.1 What Is an Animal?
Lesson Objectives
List the characteristics that all animals share.
Differentiate between invertebrates and chordates.
List and discuss the essential functions that animals perform in order to survive.
Lesson Summary
Characteristics of Animals All animals are multicellular, heterotrophic, and eukaryotic.
Their cells lack cell walls.
Types of Animals Animals are often classified into two broad categories: invertebrates and
chordates.
▶ Invertebrates do not have a backbone, or vertebral column.
• More than 95 percent of all animal species are invertebrates.
• Invertebrates are classified in at least 33 phyla, the largest taxonomic groups of animals.
Examples of invertebrates are sea stars, jellyfishes, and insects.
▶ Chordates exhibit four characteristics during some stage of development: a dorsal, hollow
nerve cord; a notochord; a tail that extends beyond the anus; and pharyngeal pouches.
• A notochord is a supporting rod that runs through the body just below the nerve cord.
• Pharyngeal pouches are paired structures in the throat region.
• Most chordates develop a backbone, or vertebral column. They are vertebrates.
What Animals Do to Survive Animals must maintain homeostasis in order to survive.
One important way to maintain homeostasis is feedback inhibition, also called negative feedback, in which the product or result of a process limits the process itself. In order to maintain
homeostasis, animals must
▶ gather and respond to information;
▶ obtain and distribute oxygen and nutrients;
▶ collect and eliminate carbon dioxide and other wastes.
They also reproduce.
Characteristics of Animals
1. Complete the graphic organizer to summarize the characteristics of animals.
Animals
have characteristics such as
Multicellular
Heterotrophic
Eukaryotic
No cell walls
Lesson 25.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
394
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Types of Animals
2. Are invertebrates rare? Explain your answer.
No, they are common. More than 95 percent of animal species are invertebrates.
3. What is an invertebrate?
An invertebrate is an animal that lacks a backbone, or vertebral column.
4. Why do invertebrates not form a clade?
They are not a clade because they are defined by the absence of a characteristic.
5. What are some examples of invertebrates?
Sea stars, worms, jellyfishes, and insects are invertebrates.
6. Look at the diagram of a chordate. Write the name of the labeled structure on the lines
below.
a.
c.
Notochord
b.
Hollow nerve cord
Tail
d.
Pharyngeal pouches
7. Are all chordates vertebrates? Explain your answer.
No, some chordates never develop a backbone.
8. What groups of animals are vertebrates?
Vertebrates include fishes, amphibians, reptiles, birds, and mammals.
9. Both snakes and earthworms have long, streamlined body shapes, but snakes are
vertebrates and earthworms are not. Why are they classified differently despite their
similarity in appearance?
Animals are classified based on body plans, not similarity of appearance. Earthworms
do not have the characteristics of a chordate, so they are considered invertebrates.
Lesson 25.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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What Animals Do to Survive
10. Complete the graphic organizer to define three ways that animals maintain homeostasis.
Animals Maintain
Homeostasis
by
Gathering and
responding to
information
Obtaining and
distributing oxygen
and nutrients
Collecting and
eliminating carbon
dioxide and other wastes
11. The diagram on the left below shows the feedback inhibition that maintains temperature
in a house. Complete the blank boxes in the diagram on the right below to show how body
temperature is maintained in a human being.
Thermostat
turns furnace
off.
Thermostat
turns furnace
on.
Sweating cools
body.
Shivering.
Muscle activity
generates heat.
House gets
cold.
House gets hot.
Body gets
cold.
Body gets
hot.
12. Describe generally how an animal’s nervous and musculoskeletal systems work together to
allow it to escape a predator.
The animal’s sensory receptors, which are part of the nervous system, sense a
predator. Its nervous system then sends signals to the musculoskeletal system to flee.
The animal’s muscles work with its skeleton to allow it to move away from the predator.
13. In complex animals, what system collects metabolic wastes and delivers them to the
respiratory and excretory systems?
the circulatory system
14. In complex animals, which three body systems work together to obtain and distribute
oxygen and nutrients?
the respiratory, digestive, and circulatory systems
Lesson 25.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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For Questions 15–24, write the letter of the correct answer on the line at the left.
D
15. What system gathers information through receptors for sound, light, chemicals,
and other stimuli?
A. respiratory
B. circulatory
C. musculoskeletal
D. nervous
C
16. Most chordates have a large number of nerve cells concentrated into a
A. backbone.
B. notochord.
C. brain.
D. pharyngeal pouch.
B
17. How does muscle tissue generate force?
A. It stretches.
B. It shortens.
C. It inflates.
D. It dilates.
B
18. How do the skeletons of insects and vertebrates differ?
A. Insects have fluid skeletons. Vertebrates have external skeletons.
B. Insects have external skeletons. Vertebrates have internal skeletons.
C. Insects have internal skeletons. Vertebrates have external skeletons.
D. Insects have external skeletons. Vertebrates have fluid skeletons.
A
19. What process allows some aquatic animals to “breathe” through their skin?
A. diffusion
B. digestion
C. excretion
D. circulation
D
20. Which structure performs a function most similar to that of gills?
A. heart
B. intestine
C. blood vessel
D. lung
D
21. Which of these functions requires the coordinated actions of the digestive,
circulatory, and excretory systems?
A. gathering O2 and distributing it to body systems
B. collecting and eliminating CO2 from tissues
C. acquiring nutrients and distributing them to body systems
D. collecting and eliminating metabolic wastes
Lesson 25.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
397
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A
22. How do the respiratory system and excretory system differ in the wastes they
eliminate?
A. The respiratory system eliminates carbon dioxide. The excretory system
eliminates ammonia.
B. The respiratory system eliminates wastes that contain nitrogen. The
excretory system eliminates carbon-based wastes.
C. The respiratory system eliminates oxygen and nitrogen. The excretory
system eliminates ammonia.
D. The respiratory system eliminates ammonia. The excretory system
eliminates carbon dioxide.
C
23. Which activity is required for survival of the species but not survival of the
organism?
A. digestion
B. excretion
C. reproduction
D. circulation
B
24. What is an advantage of asexual reproduction?
A. It increases genetic diversity in a population.
B. It produces large numbers of offspring rapidly.
C. It increases a species’ ability to evolve.
D. It produces offspring that are genetically different from the parents.
25. In what ways do invertebrates differ from vertebrates? Identify at least three groups of
invertebrates.
SAMPLE ANSWER:
Invertebrates have no backbones. They don’t have a nerve cord, a
notochord, a tail, or pharyngeal pouches. Invertebrate groups include insects, worms,
sea stars, and jellyfishes.
26. Suppose you were studying the cell walls of a multicellular organism under a microscope.
Were you studying an animal? Explain your answer.
No, it wasn’t an animal, because animal cells have no cell walls.
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