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# 20.1: Mammalian Traits

Difficulty Level: At Grade Created by: CK-12

## Lesson 20.1: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Examples of mammals include frogs, bats, whales, mice, and humans.

_____ 2. Milk contains disease-fighting molecules and nutrients a baby mammal needs.

_____ 3. The heart of a mammal consists of three chambers, making it very efficient and powerful for delivering oxygenated blood to tissues.

_____ 4. The mammalian middle ear has three tiny bones that carry sound vibrations from the inner to outer ear.

_____ 5. The cheetah is the fastest land mammal.

_____ 6. Herbivores such as zebras and lions live in herds.

_____ 7. Of all animals, mammals are most capable of learning.

_____ 8. The cerebrum controls functions such as memory and learning.

_____ 9. Clusters of alveoli in the lungs resemble tiny bunches of grapes.

_____ 10. Cellular respiration maintains the high metabolic rate in mammals.

_____ 11. Omnivores, such the bear, fox, wolf, and rat, eat both plants and animals.

_____ 12. Maintaining the high metabolic rate needed by mammals takes a lot of energy, which comes from either the sun or food.

_____ 13. Goosebumps result from tiny muscles in the skin.

_____ 14. Mammals, like all vertebrates, have four different types of teeth.

_____ 15. Mammals have hair, scales, or fur, which insulates the body to help conserve body heat.

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Characteristics of Mammals

Two characteristics are used to define the mammal class. They are mammary glands and body hair (or fur).

1. Female mammals have mammary glands. The glands produce milk after the birth of offspring. Milk is a nutritious fluid. It contains disease-fighting molecules as well as all the nutrients a baby mammal needs. Producing milk for an offspring is called lactation.
2. Mammals have hair or fur. It insulates the body to help conserve body heat. It can also be used for sensing and communicating. For example, cats use their whiskers to sense their surroundings. They also raise their fur to look larger and more threatening.

Most mammals share several other traits. The traits in the following list are typical of, but not necessarily unique to, mammals.

• The skin of many mammals is covered with sweat glands. The glands produce sweat, the salty fluid that helps cool the body.
• Mammalian lungs have millions of tiny air sacs called alveoli. They provide a very large surface area for gas exchange.
• The heart of a mammal consists of four chambers. This makes it more efficient and powerful for delivering oxygenated blood to tissues.
• The brain of a mammal is relatively large and has a covering called the neocortex. This structure plays an important role in many complex brain functions.
• The mammalian middle ear has three tiny bones that carry sound vibrations from the outer to inner ear. The bones give mammals exceptionally good hearing. In other vertebrates, the three bones are part of the jaw and not involved in hearing.
• Mammals have four different types of teeth. The teeth of other vertebrates, in contrast, are all alike.

Questions

1. What are the two characteristics used to define the mammal class?

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2. What are mammary glands?

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3. What is the role of fur or hair?

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4. List three other traits of mammals.

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5. What is unique about the mammalian ear?

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## Lesson 20.1: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Examples of mammals include
1. fish.
2. snakes.
3. whales.
4. frogs.
2. Two characteristics used to define mammals include
1. mammary glands and scales.
2. mammary glands and hair or fur.
3. mammary glands and sweat glands.
4. sweat glands and a four-chamber heart.
3. Mammals generate heat by
1. keeping a high metabolic rate.
2. laying in the sun and absorbing heat.
3. increasing blood flow to the skin.
4. all of the above
4. Mammals are unique in having
1. lungs with alveoli, tiny, sac-like structures where gas exchange occurs.
2. kidneys with alveoli, tiny, sac-like structures where blood filtering occurs.
3. alveoli, which increase blood flow to the skin allowing excess heat to escape.
4. alveoli with extra mitochondria, keeping metabolism high and generating heat.
5. Mammals with a carnivorous diet include the
1. rabbit, mouse, elephant, zebra, and monkey.
2. bear, badger, fox, human, and rat.
3. aardvark, whale, hyena, dog, dolphin, and mole.
4. giraffe, deer, elk, walrus, human, and rat.
6. Which of the following statements are true of the mammalian brain? (1) Of all vertebrates, mammals have the biggest and most complex brain for their body size. (2) The cerebrum controls functions such as memory and learning. (3) The larger the neocortex, the greater the mental abilities of an animal. (4) The area of the neocortex is greatest in humans.
1. 1 and 2
2. 3 and 4
3. 1, 2, and 3
4. 1, 2, 3, and 4
7. Mammals are social animals. Which of the following statements is correct?
1. Herbivores such as zebras and dolphins live in herds.
2. Adults in a herd surround and protect the young, who are most vulnerable to predators.
3. Adult males in a pride hunt cooperatively, which is more efficient than hunting alone.
4. all of the above
8. Tree-living mammals have a variety of different specializations for moving in trees, including
1. very long arms for swinging from tree to tree.
2. sticky pads on their arms and legs that help them cling to tree trunks and branches.
3. a prehensile tail used for climbing and hanging from branches.
4. all of the above.

## Lesson 20.1: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. producing milk for an offspring

_____ 2. include bats, whales, mice, and humans

_____ 3. part of the brain that controls functions such as memory and learning

_____ 4. eats plants and animals

_____ 5. eats animals

_____ 6. eats plants

_____ 7. swinging from branch to branch

_____ 8. produce milk after the birth of offspring

_____ 9. the large muscle that extends across the bottom of the chest below the lungs

_____ 10. provide a very large surface area for gas exchange

_____ 11. covering of brain

_____ 12. tree-living animals

Terms

a. alveoli

b. arboreal

c. brachiation

d. carnivore

e. cerebrum

f. diaphragm

g. herbivore

h. lactation

i. mammals

j. mammary gland

k. neocortex

l. omnivore

## Lesson 20.1: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. Mammals have four limbs and produce ____________ eggs.

2. ____________ glands produce milk after the birth of offspring.

3. ____________ or fur insulates the body to help conserve body heat.

4. ____________ in the lungs provide a very large surface area for gas exchange.

5. Three tiny bones in the ____________ give mammals exceptionally good hearing.

6. Mammals can generate and conserve heat when it’s ____________ outside.

7. The cells of mammals have many more ____________ than the cells of other animals, allowing mammals to have a high metabolic rate.

8. The larger the surface area of the brain's ____________, the greater the mental abilities of an animal.

9. In some mammals, a ____________ tail is used for climbing and hanging from branches.

10. Many mammals live in social groups, such as ____________ of elephants or prides of lions.

11. The four-chambered mammal ____________ is very efficient at delivering oxygenated blood to tissues.

12. Mammals have ____________ different types of teeth.

## Lesson 20.1: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Describe three characteristics of mammals.

Feb 23, 2012

May 11, 2015

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