Name Date Class. From the list below, choose the term that best completes each sentence.

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1 Name Date Class Structure and Function of Vertebrates Review and Reinforce Birds Understanding Main Ideas Answer the following questions. 1. What are four characteristics that all birds share? 2. What are three adaptations that enable birds to fly? 3. What are two functions of feathers? 4. Briefly describe a bird s heart and circulatory system. 5. Give two examples that show how the bills of birds allow them to live in diverse environments. Building Vocabulary From the list below, choose the term that best completes each sentence. contour feather bird crop gizzard down feather 6. A bird s food is stored in its before it is digested. 7. A is soft and used for insulation. 8. A is an endothermic vertebrate that lays eggs and has feathers and a four-chambered heart. 9. The is a muscular, thick-walled part of a bird s stomach where partially digested food is ground up. 10. A gives shape to a bird s body and helps a bird balance and steer during flight. 97 Structure and Function of Vertebrates

2 Name Date Class Structure and Function of Vertebrates Enrich How Do Birds Fly? The shape of a bird s wing is streamlined, meaning it is curved on top and flatter underneath. The wing allows air to flow smoothly over and under it, as in the diagram below. Air flow When a bird is between wing beats, the angle and shape of the wing cause the air to move faster above the wing than below it. The faster-moving air above the bird s wing exerts less pressure than the slower-moving air below the wing. The difference in pressure above and below the wings as a bird moves through the air produces an upward force that causes the bird to rise. That upward force is called lift. Before the bird can use lift to fly, it must have some way of getting off the ground. To get into the air, a bird pushes off with its legs and moves forward at the same time. The bird must move forward to make air move over its wings. Sharply pulling down its wings provides the power that pushes the bird forward. The forward motion creates lift. Answer the following questions below on a separate sheet of paper. 1. How does the structure of a bird s wings affect air movement around it? 2. As air moves faster, what happens to the pressure it exerts? 3. How does the difference in pressure above and below the wings help a bird fly? 98

3 Name Date Class Structure and Function of Vertebrates Review and Reinforce Mammals Understanding Main Ideas Answer the following questions. 1. What are four characteristics shared by all mammals? 2. What information can you infer from the size and shape of a mammal s teeth? 3. Briefly describe a mammal s heart and circulatory system. 4. Where in a mammal s body does oxygen enter the bloodstream? 5. If a mammal has a dense coat of fur, what might you infer about the climate where that mammal lives? Building Vocabulary From the list below, choose the term that best completes each sentence. monotremes placenta diaphragm mammal marsupial 6. are mammals whose young are born at a very early stage of development they usually continue to develop in a pouch on their mother s body. 7. A is an organ that passes materials such as food and oxygen from the mother to the developing embryo, and carries the embryo s wastes away. 8. There are just three species of. 9. A large muscle called the helps mammals breathe. 10. Every has hair or fur, but sometimes not very much. 100

4 Name Date Class Structure and Function of Vertebrates Enrich Identifying Mammal-like Fossils Many of the characteristics that scientists use to identify an animal as being a mammal are seldom or never preserved as fossils. Some of these are a fourchambered heart, skin covered with fur or hair, and giving birth to live young. So how do paleontologists recognize the fossils of mammals and their close relatives? Not surprisingly, paleontologists use characteristics of the skeleton to identify both mammals and their mammal-like reptile relatives. For example, Figure 1 shows the skull of the very early mammal-like reptile Dimetrodon. Like most other vertebrate skulls, it has paired openings in the front for nostrils and near the middle for eyes. Unlike most vertebrates, it also has an extra paired opening at the back of the skull, behind the eye. This opening is an adaptation that makes room for the jaw muscles that fill the back of the skull to bulge outward, allowing the animal to bite harder. It is a characteristic found both in living mammals and in their extinct relatives. Extra Opening Eye Nostril A B C Figure 1 Figure 2 Study Figure 2 and fill in the table, answering yes or no. Then answer the questions below on a separate sheet of paper. Specimen Nostril opening present? Eye opening present? Extra opening behind eye present? A B C 1. Based on the information you have recorded in the table, which of the skulls in Figure 2 do you think belong to mammals or mammal-like reptiles? Why? 2. What other characteristic of mammals do you see in the skulls in Figure 2? Does this characteristic appear in all of the specimens, or only in mammals and mammal-like reptiles? 101 Structure and Function of Vertebrates

5 Name Date Class Changes Over Time Review and Reinforce Classifying Organisms Understanding Main Ideas Answer the following questions in the space provided. 1. List the major levels of classification, starting with the highest level. 2. What three characteristics are used to place organisms into domians and kingdoms? Building Vocabulary Match each term with its definition by writing the letter of the correct definition in the right column on the line beside the term in the left column. 3. classification 4. binomial nomenclature 5. eukaryote 6. genus 7. taxonomy 8. prokaryote a. naming system developed by Carolus Linnaeus b. process of grouping things based on their similarities c. first word in an organism s scientific name d. organism whose cell lacks a nucleus e. the scientific study of how things are classified f. organism whose cell(s) contain a nucleus 78

6 Name Date Class Changes Over Time Enrich How Many Species of Animals Are There? There are more species of insects than any other type of animal on Earth. The majority of animals, including insects, live in the tropics. If you can estimate how many species of insects there are in the tropics, you can get a pretty good estimate of the number of species of animals on Earth. Over the years, entomologists (scientists who study insects) have been discovering and naming new kinds (species) of insects, and now over a million kinds of insects are known. Dr. Terry Erwin, an entomologist at the Smithsonian Institution, studies beetles. Beetles make up a large percentage of insects and related animals. By estimating the number of species of beetles in the tropics, Dr. Erwin was able to estimate the total number of species of animals in the world. Dr. Erwin used the following information to arrive at his estimate: Dr. Erwin found 1,200 species of beetles living in Luehea seemannii trees. Of those 1,200 species of beetles, he estimated that 163 are found only in the Luehea seemannii tree, and not in other species of trees. There are about 50,000 species of trees in the tropics. Beetles make up about 40% of insects and related animals. Dr. Erwin estimated that there are about twice as many species of insects and related animals in tropical trees as there are on the ground of the forest. Answer the following questions on a separate sheet of paper. Use a calculator to make the calculations. 1. If each kind of tree has 163 species of beetles that are found only on that type of tree but no others, how many kinds of beetles are there in tropical trees? 2. Using your answer from question 1, estimate how many species of insects and related animals there are in tropical trees. 3. Using your answer from question 2, estimate how many species of insects and related animals are on the forest floor in the tropics. 4. Using your answer from questions 2 and 3, estimate how many species of insects and related animals there might be in the trees and the forest floor together in the tropics. 5. Why did Dr. Erwin focus on tropical forests to estimate the total number of animal species in the world? 6. What are some likely sources of error in Dr. Erwin s estimation method? Changes Over Time 79

7 Name Date Class Changes Over Time Review and Reinforce Branching Trees Understanding Main Ideas Answer the questions in the space provided. 1. What indicates how recent a common ancestor probably is? 2. Explain what a branching tree diagram shows. 3. How are the organisms on a branching tree diagram grouped? _ Use the letters a e to order the groups in a branching tree diagram from lowest to highest. 4. organisms with two shared derivative characteristics 5. Common Ancestor 6. organisms with the most shared derivative characteristics 7. organisms with no shared derivative characteristics 8. organisms with one shared derivative characteristic Building Vocabulary Define the term in the space provided. 9. shared derivative characteristic Changes Over Time 81

8 Name Date Class Changes Over Time Enrich A Branching Tree for Mammals Vertebrate groups include fishes, amphibians, reptiles, birds, and mammals. Of these groups, only mammals produce milk to feed their young. Mammals are divided into three groups: monotremes, marsupials, and placental mammals. Female monotremes release milk through pores in their skin; marsupials and monotremes both release milk through structures called nipples. Before birth, the young of placental mammals receive needed materials through an organ called the placenta. Placental mammals are further divided into groups. The members of one of the groups, called primates, have opposable thumbs. An opposable thumb is a thumb that can touch all four of the other fingers. Read the table below, which lists the characteristics of some vertebrates. Then answer the questions on a separate sheet of paper. Vertebrate Feed Young With Milk Characteristics of Some Vertebrates Milk Released Through Nipples Have a True Placenta Chimpanzee yes yes yes yes Duckbill platypus yes no no no Elephant yes yes yes no Koala yes yes no no Rattlesnake no no no no 1. Use the characteristics in the table to draw a branching tree diagram that classifies these vertebrates. 2. Which animal in the table is not a mammal? How do you know? 3. Is a koala a monotreme, marsupial, or placental mammal? How do you know? 4. Does an elephant have an opposable thumb? 5. Which animal has all the characteristics in the table? What is its position on the branching tree? Have an Opposable Thumb 82