Deck 43: Mammals

Question 1

Scientists classify amniotes from 300 million years agointo two major groups: the diapsids and the synapsids. A unique subset of synapsids from 245 million years agois made up of therapsids. Modern mammals are grouped into the monotremes, the marsupials, and the placental mammals.
Part A Describe modem scientific hypotheses about the evolutionary relationships among these groups of amniotes.
Part B Describe the kinds of evidence that scientists examine to test these hypotheses.

Answer 1

Ancestor of mammals appeared 300 million year ago. Carl Linnaeus coins Word "mammal". Mammals belong to the class Mammalia. Among modern mammals, only we human being are bipedal in locomotion. Mammals include most of the largest animals. They maintain homeostasis. They are easily adapted to external environment. They possess many characteristics such as body hair, mammary glands, and four-chambered heart. Except monotremes, all mammals are viviparous.
Amniotes were first terrestrial vertebrates and they seem to have split into two groups. Synapsids gave rise to mammals. They had specialized teeth and smaller back teeth. Mammals thought to have descended from therapids, four legged mammals.
Part a
According to the modern hypothesis ancestors of mammals appeared more than 300 million year ago. Amniotes split into two groups one of them is synapsids. Another group gave rise to dinosaurs. Synapsids were small but large synapsids appeared by the early Permian. Early synapsids recognized by single opening in their skull similar to the skull of later synapsids and mammals. During late Permian period, therapids appeared and gave rise to mammals. Studying fossils indicates that several features of mammals evolved in early therapids. Limbs of mammals and early therapids are just below their body. Three different kind of mammals appeared during late cretaceous. According to scientist because of some catastrophic event dinosaurs become extinct and mammals flourished.
Part b
Scientist used various evidences such as fossils to test their hypothesis. Early synapsids recognized by single opening in their skull similar to the skull of later synapsids and mammals. Studying fossils indicates that several features of mammals evolved in early therapids. Limbs of mammals and early therapids are just below their body. Some of the early synapsids had a sail like structure, which scientists thought to have blood vessels that control temperature.

Question 2

INTERPRETING GRAPHICS: The illustration below shows the skulls of two different mammals. Use the illustration to answer the question that follows.

Which of the following accurately describes the differences between these skulls?
F) Skull A has more teeth than skull B does.
G) Skull A has more brain capacity than skull B does.
H) Skull A is the skull of a primate, and skull B is not the skull of a primate.
J) Skull A is the skull of an ape, and skull B is the skull of a human.

Answer 2

Mammals include most of the largest animals. They maintain homeostasis. They are easily adapted to external environment. They possess many characteristics such as body hair, mammary glands, four chambered heart.
Mammals can maintain a constant body temperature irrespective of external environment. This manner of controlling body temperature is called endothermy. They release their own body heat by metabolism or some other ways.
Skull is a bony structure. It protects brain and support face. It is the anterior most part of skeletal system.
Hence, options F, G and H are incorrect.
Human skulls have a rounded braincase that is much larger than that of a chimpanzee. Facial skull is slanting in case of chimpanzee whereas facial plane is nearly vertical in human skull.
Hence, the correct option is

Question 3

Analyzing Results In a famous study conducted 200 years ago, the Italian scientist Lazzaro Spallanzani showed that a blinded bat could still fly and capture insects. However, a bat whose ears had been plugged with wax could neither fly nor hunt. Explain these results.

Answer 3

Order chiroptera includes only true flying mammals, the bats. It includes more than 900 species of bat and they live throughout the world. Front limb of bat are modified into wings with a membrane of skin stretches between extremely long finger bones. They capture prey by echolocation.
Bats are mostly active during night and use a process called echolocation for searching food. They can determine size distance and speed of the objects or prey in their way with the help of echolocation
Bats are only mammals that can naturally fly by flapping their digits. Large ears provide many advantages to the bats mainly in echolocation. There ear are specialized and they can separate their calls and echolocations easily. This helps them in identifying the size, distance of the prey in dark.
Lazzaro spallanzani showed that a blind bat could still fly and capture insects even when they do not produces any sound because of echolocation.
When ear of bat is stuffed with wax they could neither fly nor hunt because wax blocked their sense organs present in external ear of bat. Bat uses these sense organs present in eternal ear to echolocate prey. If there sense organs are impaired bat will be unable to hunt the prey.

Question 4

Recognizing Relationships Propose a functional reason why endothermy is associated with an enlarged cerebrum.

Question 5

Calculating Information From the information about hominid brain size and fossil ages in this section, construct a graph of how hominid brain sizes changed with time.

Question 6

Mammals and birds are endothermic vertebrates.
Describe the functional costs and benefits of endothermy.

Question 7

Describe the important adaptations of the teeth of mammals.

Question 8

INTERPRETING GRAPHICS: Study the two skulls below. Which is more like a mammal skull? Justify your answer.

Question 9

Give an example of each from the major orders of mammals.

Question 10

DIRECTIONS: Choose the letter of the answer choice that best answers the question. Which of the following structures is found in all modem mammals and birds?

A) hair
B) skull with teeth
C) lungs with air sacs
D) heart with four chambers

Question 11

Compare the teeth of rodents to those of lagomorphs.

Question 12

What is the function of hair in mammals?

Question 13

Which continent is a natural home of both monotremes and marsupials?

Question 14

Use the following terms in the same sentence: mammals , synapsids , therapsids , and endothermy.

Question 15

Describe two mammalian adaptations for digesting plants.

Question 16

Identify two differences between the skull of a mammal and the skull of a reptile.

Question 17

What is unusual about the incisors of rodents?

Question 18

DIRECTIONS: Choose the letter of the answer choice that best answers the question. What is the function of a mammalian diaphragm?
F) enables efficient breathing
G) provides nourishment for young
H) carries the young inside the uterus
J) keeps oxygenated blood separate in heart

Question 19

Identify the part of the brain that is relatively larger in mammals than in other animal groups.

Question 20

Compare the characteristics of early synapsids, therapsids, and modern mammals.

Question 21

Compare artiodactyls to perissodactyls.

Question 22

Word Roots and Origins The word incisor is derived from the Latin incidere , which means "to cut into." Using this information, explain why the term incisor is a good name for the type of tooth that the term describes.

Question 23

Describe the distinguishing characteristic of placental mammals.

Question 24

Differentiate between monotremes, marsupials, and placental mammals.

Question 25

Compare manatees to toothed whales.

Question 26

DIRECTIONS: Choose the letter of the answer choice that best answers the question. Which of these animals is a marsupial?

A) lion
B) echidna
C) opossum
D) duckbill platypus

Question 27

Give an example of an animal from each of the 12 orders of placental mammals.

Question 28

Analyzing Theories Describe a possible species that would be a transitional form between therapsids and mammals.

Question 29

Inferring Relationships Give an adaptive reason why the pouch of the marsupial mole, a burrowing animal, opens toward the rear of its body.

Question 30

Identify six key characteristics of mammals.

Question 31

Compare the characteristics of artiodactyls and perissodactyls.

Question 32

Examining Evidence What factors limit biologists' knowledge of early mammals?

Question 33

Applying Information Why is flying lemurs a poor name for members of the order Dermoptera?

Question 34

DIRECTIONS: Choose the letter of the answer choice that best answers the question. Which of these animals is a monotreme?
F) zebra
G) opossum
H) kangaroo
J) duckbill platypus

Question 35

Compare sirenians, pinnipeds, and cetaceans.

Question 36

Making Comparisons Which trait(s) do monotremes share with reptiles?

Question 37

Making Comparisons Cetaceans live in cold ocean waters yet lack fur. Explain this.

Question 38

Relate the characteristics of therapsids and synapsids to those of mammals.

Question 39

Describe the distinguishing characteristics of primates.

Question 40

A mammal eats about 10 times as much food as a lizard of the same size. Explain this difference.

Question 41

Identify which characteristics humans share with primates and which are unique to humans.

Question 42

DIRECTIONS: Choose the letter of the answer choice that best answers the question. Which of the following structures is found in cats but not in opossums?

A) hair
B) uterus
C) placenta
D) mammary gland

Question 43

Compare fossil australopithecines with fossil humans.

Question 44

Compare a mammalian heart to a reptilian heart.

Question 45

What kind of evidence shows that chimpanzees are the closest living relatives of humans?

Question 46

Relate the evolution of mammals to the mass extinction of Cretaceous reptiles.

Question 47

CONCEPT MAPPING Use the following terms to create a concept map that compares the process of reproduction in different animal groups: reptiles , monotremes , marsupials , placental mammals , oviparous , viviparous , and placenta.

Question 48

Describe the function of a rumen.

Question 49

Identify several traits that differ among the variety of hominids known from fossils.

Question 50

INTERPRETING GRAPHICS: The illustration below shows the skulls of two different mammals. Use the illustration to answer the question that follows.

What can be inferred about these mammals?
F) Mammal A has more fat than mammal B.
G) Mammal A has more hair than mammal B.
H) Mammal A eats more meat than mammal B.
J) Mammal A eats more grass than mammal B.

Question 51

Relating Structure and Function Mammalian species that live in very cold environments are usually larger than species of the same genus that live in warmer climates. Propose an explanation for this. (Hint: Consider the effect that increasing size has on volume and surface area.)

Question 52

Compare a mammalian brain to a reptilian brain.

Question 53

Describe how members of Homo habilis differ from australopithecines.

Question 54

Compare the costs and benefits of endothermy for mammals.

Question 55

Analyzing Processes Some kinds of mice give birth about 21 days after mating. Why might this characteristic make mice ideal laboratory animals for experiments dealing with mammalian development and heredity?

Question 56

Compare the developmental patterns of monotremes, marsupials, and placental mammals.

Question 57

Contrast the multiregional hypothesis and the recent-African-origin hypothesis.

Question 58

DIRECTIONS: Complete the following analogy. hair : insulation :: milk :

A) armor
B) circulation
C) endothermy
D) nourishment

Question 59

Forming Hypotheses Sloths are arboreal xenarthrans that spend most of their lives hanging upside down from tree branches as they feed in tropical forests. Most sloths have green algae growing in tiny pits in their hair. What advantage might each species gain from this relationship?

Question 60

Analyzing Information What is the advantage of large ears to a bat that is active at night?

Question 61

Analyzing Processes Propose an explanation of the adaptive value of bipedalism in hominids.

Question 62

For each pair of terms, explain how the meanings of the terms differ.
A. viviparous and oviparous
b. septum and diaphragm
c. canine and molar
d. rumen and cecum
e. placenta and charion
F. anthropoid primate and hominid

Question 63

Explain how the structure of the mammalian heart supports endothermy.

Question 64

Applying Concepts In recent years, surgeons have tried transplanting baboon and pig hearts into humans. Explain why surgeons tried these hearts rather than a large turtle's heart.

Question 65

Applying Concepts What ecological relationship does a cow have with the bacteria in its rumen?

Question 66

Analyzing Models Using Figure 43-20, name the hominids that would have coexisted 2 million, 1 million, and 50,000 years ago.